US Quantification of Liver Fat: Past, Present, and Future

David T Fetzer, Theodore T Pierce, Michelle L Robbin, Guy Cloutier, Arjmand Mufti, Timothy J Hall, Anil Chauhan, Reinhard Kubale, An Tang

Radiographics. 2023 Jul;43(7):e220178. doi: 10.1148/rg.220178

Hepatic steatosis is a growing public health problem with crescent clinical impact and associated medical costs and Non-alcoholic fatty liver disease (NAFLD) is now the most common cause of chronic hepatopathy worldwide. [1]

This article focuses on the urgent need to find a method capable of detecting and quantifying liver fat that is reliable, reproducible, non-invasive and accessible to the general population.

US is a widely availability and non-invasive method and manufactures have been working in the devolvement of quantitative software to overcome the subjective evaluation of hepatic steatosis using the classical B-mode. This classic approach is not sensitive enough, especially when liver fat content is less than 20% and in patients with obesity or renal disease. [2,3]

The authors begin by praising the role of MRI proton-density fat fraction as the most accurate non-invasive biomarker of hepatic steatosis. However, MRI is not widely available for screening and surveillance of the general population, which becomes quite limiting taking into account the dimension and prevalence of this pathology. [4]

The article focuses especially on methods that use ultrasound to evaluate hepatic steatosis, emphasizing the limitations and advantages of each technique.

A non-image-guided technique, the Controlled Attenuation Parameter (CAP), is only available in vibration-controlled transient elastography (VCTE) devices and it is widely available. Nevertheless, it is a non-image-guided method and therefore does not allow avoiding masses, vessels and other possible artefacts. Furthermore, it is not a reliable method in the presence of ascites, obesity and in the presence of steatohepatitis and fibrosis.

The qualitative assessment of steatosis by ultrasound has been carried out since 1970 and is based on the assessment of the echogenicity of the liver and the comparison with the echogenicity of the right kidney and pancreas as well as the conspicuity of the portal vessels, gallbladder walls and diaphragm-lung interface. However, this method is subjective and does not allow the severity of the stenosis to be quantified, making it difficult to follow these patients over time.

The hepatorenal index is a semiquantitative method that is calculated by dividing the ROI of the liver parenchyma and the right renal cortex. This method is reproducible and intuitive; nevertheless, it is operator-dependent and there are no established cut-offs. Furthermore, it demands the presence of a normal kidney.

The attenuation coefficient, backscatter coefficient and speed of sound are other recently introduced methods that allow a quantitative assessment of steatosis.

The attenuation coefficient is a relatively intuitive and reproducible method that quantifies the acoustic energy that is lost when crossing the liver parenchyma. [5]

In turn, backscatter coefficient measures ultrasound echoes generated by reflection and scattering, which determine the brightness in the image generated in B-Mode.

Finally, Speed of Sound is influenced by the stiffness and the density of the liver and is inversely correlated with steatosis.

These three methods can be confounded by several factors such as near-field reverberation artefacts, liver heterogeneity or fibrosis.

Crohn’s disease phenotype analysis with iodine density from dual‐energy CT enterography

Dane B, Li X, Goldberg JD, O'Donnell T, Le L, Megibow A

Abdom Radiol (NY). 2023;48(7):2219-2227. doi:10.1007/s00261-023-03923-z

This study investigated the correlation between dual-source dual-energy CT enterography (dsDECTE) iodine density and Crohn's disease phenotypes, providing insights into disease progression and severity.

The Society of Abdominal Radiology and American Gastroenterological Association (SAR-AGA) jointly developed recommendations for interpreting CT enterography in small bowel Crohn's disease [1]. These guidelines introduced a morphological framework to describe the inflammation and progression of Crohn's disease [2, 3]. Transmural inflammation often leads to complications like strictures, sinus tracts, fistulas, and abscesses [4, 5]. Consequently, the consensus statement grouped imaging findings into Crohn's disease patterns or phenotypes, reflecting different stages of disease activity and severity:

• Crohn’s disease with no imaging signs of active inflammation
• Active inflammatory small bowel Crohn’s disease without luminal narrowing
• Active inflammatory small bowel Crohn’s disease with luminal narrowing
• Stricture without active inflammation
• Stricture with active inflammation
• Penetrating Crohn’s disease

CT enterography is the recommended modality to assess and monitor Crohn's disease activity [6]. Spectral CT has the unique advantages over conventional CT to achieve material differentiation, shifting the paradigm from qualitative to quantitative imaging. This holds particularly true for iodine density [7], which correlates with inflammation and disease activity better than Hounsfield Units [8]; however, no previous investigations correlated iodine density with Crohn’s disease phenotypes as defined by the SAR-AGA consensus.           

The initial population consisted of 451 patients with “Crohn’s disease” in the radiology report, scanned from May 2017 to December 2021. After excluding patients with no Crohn’s disease diagnosis based on clinical or endoscopic assessment, no endoscopy within 4 months of CT, and no subsequent ds-DECTE, final patient population included 50 patients (31 males, 19 females).

Each patient underwent dsDECTE on a third-generation dual-energy CT scanner, small bowel distention was obtained by administration of 900 mL of neutral oral contrast medium, while a single acquisition was performed after i.v. contrast medium injection based on patient’s weight.

Two readers, blinded to dual-energy CT iodine density, clinical information, and original radiology report, categorized Crohn's disease as follows:

• Group 1 - stricture without active inflammation (n= 4)
• Group 2 - no active inflammation (n= 12)
• Group 3 - active inflammation without luminal narrowing (n= 2)
• Group 4 - active inflammation with luminal narrowing (n= 13)
• Group 5 - stricture with active inflammation (n= 9)
• Group 6 - penetrating disease (n= 10)

Subsequently, small bowel mural iodine density and mural iodine density normalized to the aorta were semiautomatically determined. Mean iodine density was 2.14 ± 1.1 mg/mL for groups “1 or 2”, 3.54 ± 1.7 mg/mL for groups “3 or 4”, and 5.50 ± 3.3 mg/mL for group 5, and 3.36 ± 1.4 mg/mL for group 6. The differences among the groups were statistically significant (P = 0.001), especially for groups “1 or 2” versus group 5. Iodine density normalized to the aorta was 21.2 ± 6.1% for groups 1 or 2, 39.47 ±9.7% for groups 3 or 4, 40.98 ± 11.7% for group 5, and 35.01 ± 7.6% for group 6. Also the differences were statistically significant (P < 0.001), especially when comparing groups “1 or 2” versus the other groups.

A retrospective preliminary study of intrapancreatic late enhancement as a noteworthy imaging finding in the early stages of pancreatic adenocarcinoma

Yoshihiro Konno, Yasuhiro Sugai, Masafumi Kanoto, Keisuke Suzuki, Toshitada Hiraka, Yuki Toyoguchi & Kazuho Niino

European Radiology 33, 5131–5141 (2023). doi.org/10.1007/s00330-022-09388-w

Pancreatic adenocarcinoma (PAC) represents the most common primary pancreatic malignancy (90%) [1]. Accounting for 2% of all cancer cases, it has the lowest 5-year survival rate of all solid cancers (5-9%) and is the fourth-leading cause of cancer-related death in USA and Canada [1,2]. Due to its aggressive behavior, early diagnosis is critical for appropriate management. Imaging has a central role in this regard as early PAC is often challenging to diagnose clinically [2].

CT and MRI are the cornerstones of PAC detection, staging, treatment response assessment and recurrence diagnosis, with CT often being the test of choice due to its reproducibility and availability [1,3]. The primary imaging finding is a hypo-attenuating/intense pancreatic mass on contrast-enhanced studies [4]. However, up to 27% of tumors <2 cm in size can be isoattenuating at CT [4]. Indirect findings (IFs) include main pancreatic duct abnormalities (MPDA) with dilatation (when associated with common bile duct dilatation = “double duct”
sign), contour distortion, focal pancreatic parenchymal atrophy (FPPA), vascular encasement and loss of pancreatic lobulation [3,4]. The most common focal pancreatic abnormalities noted in pre-diagnostic CT (at least 1 year before the diagnosis of PAC) were FPPA, focal faint parenchymal enhancement and focal MPDA [5].

The aim of this retrospective study was to analyze intrapancreatic late enhancement (ILE) in pre-diagnostic CT studies of patients with pathologically confirmed PAC and its potential significance as an early indirect finding in PAC. The final study population enrolled 32 patients (23 men and 9 women, median age 72 years), with pathologically confirmed PAC (surgically or by biopsy). The main inclusion criterion was a contrast-enhanced CT (CECT) study performed 6 months to 5 years prior to the pathological diagnosis of PAC, without a visible focal pancreatic mass. Exclusion criteria included patients with (a) previous pancreatectomy, (b) difficult distinction from inflammatory changes and (c) carcinoma in situ.

Technically, all CECT exams were obtained using a helical CT (64-320 rows) with 1 or 5 mm thick slices, with either monophasic (late phase 120s after contrast injection) or multiphasic (early and late arterial, portal and late phase at 180s after contrast injection) protocols. ILE was defined as a focal enhancement in the pancreatic parenchyma of any size or shape, with subsequent quantitative evaluation in Hounsfield Units (HU) by calculating the ILE-to-pancreas contrast (HU [region of ILE] – HU [pancreatic parenchyma]). Other IFs were also defined in the study, including FPPA and MPDA, as well as cystic lesions. To verify the potential significance of ILE, two independent experienced radiologists, blind to all clinical data, reviewed representative pre-diagnostic CT images and indicated potential sites where PAC would become apparent in the future. The evaluation was done both before and after the two observers received lectures on the significance of ILE as an IF in PAC, with subsequent comparison between the two assessments in terms of lesion detection and interobserver agreement.

The positive group (with present IFs) included 23 cases (72%), without any significant differences in terms of demographics, preexisting conditions or time interval to diagnosis compared to the negative group (without IFs). Incidental PAC (clinically asymptomatic) was significantly more frequent in the positive group with a tendency for more frequent body/tail lesions, while in the negative group tumor size tended to be larger at diagnosis.

Understanding Reader Variability: A 25-Radiologist Study on Liver Metastasis Detection at CT

Hsieh SS, Cook DA, Inoue A, Gong H, Sudhir Pillai P, Johnson MP, Leng S, Yu L, Fidler JL, Holmes DR 3rd, Carter RE, McCollough CH, Fletcher JG

Radiology 2023 Feb;306(2):e220266. doi: 10.1148/radiol.220266.

Interreader variability in radiology exists even for routine tasks, such as detection of hepatic metastases at CT. Various factors may contribute to this variability, including reader experience, sub-specialization and patterns of image navigation (1, 2). Lesion characteristics might also affect interreader variability, as they are heterogenous in nature (3). Sources of error in lesion detection can generally be categorized as either visual search or cognitive classification error, i.e. the lesion is missed because the eye never fixates it or because it is not reported after eye fixation (4). These errors can be differentiated by measuring gaze time with eye tracking. While interreader variability can undermine patient care by misdiagnosis, only marginal efforts have been made to address these performance differences among radiologists.

In this prospective observational study, the authors aimed to determine the impact of (a) reader experience, (b) image navigation patterns, and (c) eye gaze time on interreader variability of missed liver metastases in contrast-enhanced abdominal CT.

Twenty-five radiologists from a single academic center were recruited to screen 40 abdominal, portal venous CT studies for hepatic metastases. Raters had different experience and training levels, consisting of 9 abdominal subspecialists, 5 non-abdominal subspecialists and 11 trainees. They reviewed each study on a custom viewing workstation with an integrated eye tracker, while data on image navigation was collected (interpretation time, time in liver window and zoomed images, number of scrolls in axial and coronal stack). Gaze time near metastases was calculated, as well as the number of times a reader gazed at the same metastasis in both axial and coronal plane (correlated view). Blinded readers circumscribed the suspected hepatic metastases and scored their confidence from 0 to 100. Confidence scores of 0 indicated a benign lesion and would be disregarded in later analysis. Thirty-two studies contained 91 hepatic metastases proven by histopathology or progression; the other eight had no metastases.

Diagnostic performance was measured by area under the jackknife alternative free-response receiver operating characteristic (JAFROC) curve and per-metastasis sensitivity.

When comparing reader groups, abdominal specialists showed a significantly higher JAFROC performance as they had greater mean confidence in true-positive circumscriptions. However, there was no significant difference in sensitivity or false-positive findings among groups.

With regards to image navigation patterns, there were significant associations between sensitivity and the following six navigation variables: Interpretation time, time in liver windows, time spent gazing at coronal images, coronal scrolls, number of circumscriptions, and correlating views between axial and coronal images. Interestingly however, the number of false-positive findings also increased with these navigation variables, although not significantly. Therefore, navigation variables were not associated with improved JAFROC.

Eye-tracking data showed that of 377 missed metastases, 71%, 40% and 7 % occurred after a gaze time longer than 0.5, 2.0 and 10.0 seconds, respectively. Prior studies suggest that gaze times of less than 0.5 second represent search errors, and gaze times longer than 2 seconds represent classification errors.

Factors Associated With Complete Pathologic Necrosis of Hepatocellular Carcinoma on Explant Evaluation After Locoregional Therapy: A National Analysis Using the UNOS Database

Sarwar A, Bonder A, Hassan L, Malik MS, Novack V, Curry M, Ahmed M.

AJR Am J Roentgenol. 2023 May;220(5):727-735. doi: 10.2214/AJR.22.28385. Epub 2022 Dec 7. PMID: 36475810.

Hepatocellular carcinoma (HCC) is one of the most common indications for liver transplant (LT) [1]. Complete pathologic necrosis (CPN) obtained by different types of locoregional therapies (LRTs) before LT is associated to a lower 5-year estimated risk of recurrence and better 5-years recurrence-free and disease-specific survival rates [2].

So far, the most widespread LRT is transarterial chemoembolization (TACE) [3-6], followed by thermal ablation and transarterial radioembolization [TARE]. However, the choice of the most appropriate locoregional therapy varies widely among institutions. Notwithstanding the importance of CPN as a significant predictor of recurrence-free survival and overall survival, The American Association for the Study of Liver Diseases guidelines for treating HCC do not recommend a particular type of LRT over another as a bridge to LT [7] due to the paucity of studies reporting an improved survival.

The current study [8] aims to examine the type of LRT associated with higher rates of CPN on explant evaluation, as well as patients characteristics, HCC and transplant-center features associated.

The final study population consisted of 6265 patients (median age, 62 years [IQR, 58–66 years]; 1505 [23.1%] women, 4760 [76.9%] men) who underwent LT after a single type of LRT for HCC measuring 3 cm or smaller.

From The United Network for Organ Sharing (UNOS) database authors obtained information about the necrosis percentage at the explant evaluation, patient’s clinical and laboratory features, HCC’s characteristics like size and several transplant center’s data (e.g. median waiting time for LT).

Out of the 6265 patients included, 4352 (69.5%) performed TACE, 1217 (19.4%) underwent thermal ablation and 696 (11.1%) were treated by TARE. On explant evaluation, CPN for all HCCs was achieved in 23.5% (1475/6265) of patients.

The CPN rate was 18.5% (805/4352) in patients who underwent TACE, 35.8% (436/1217) in patients who underwent thermal ablation, and 33.6% (234/696) in patients who underwent TARE.

Centers (n = 118) were stratified into tertiles according to the CPN rate; the first tertile comprised 40 centers with a CPN rate of 0.0–17.5%; the second tertile comprised 39 centers with a CPN rate of 17.6–27.6%, and the third tertile comprised 39 centers with a CPN rate of 27.7–50.0%. Centers in the second and third tertiles performed higher number of thermal ablation (23.6% and 25.5%, respectively) than centers in the first tertile (14.4%) (p = .02). A higher number of TAREs were performed in the third tertile (14.7%) than centers in the second tertile (12.3%) and first tertile (5.2%) (p = .03). These data showed a higher CPN rate percentage in centers where TAREs and thermal ablations were  performed more frequently than TACEs.

Considering laboratory findings of patients with CPN and without CPN, authors reported α-fetoprotein level (AFP) at the time of LRT lower in CPN group (6.0 ng/mL vs 7.0 ng/mL, p < .001), as well as model for end-stage liver disease (MELD) score at the time of LRT (10.0 vs 11.0, p < .001). Patients with CPN, were also more likely to have a single HCC (79.7% vs 67.6%, p< .001) and a smaller median size of the largest HCC (1.0 cm vs 1.3 cm, p< .001).Despite several limitations of the study, mainly related to the lack of patients’ information (the reason why a particular type of LRT was selected, the position of HCC within the liver, radiologists experience, technical aspects of LRTs, post procedural complications, survival rate after LT), TARE seems to be superior to TACE and equivalent to thermal ablation in terms of CPN rates.

Assessment of main pancreatic duct cutoff with dilatation, but without visible pancreatic focal lesion on MDCT: a novel diagnostic approach for malignant stricture using a CT-based nomogram

Chae Young Lim ¹, Ji Hye Min ², Jeong Ah Hwang ¹, Seo-Youn Choi ³, Seong Eun Ko ¹

European Radiology 2022 Dec;32(12):8285-8295. doi: 10.1007/s00330-022-08928-8. Epub 2022 Jun 21.

Pancreatic ductal adenocarcinoma (PDAC) typically manifests as a hypoattenuating mass with upstream main pancreatic duct (MPD) dilatation on contrast-enhanced dynamic CT [1]. However, it is not rare in clinical practice to encounter an isoattenuating PDAC, thereby manifesting only as an isolated MPD dilatation [2, 3]. In this situation, indirect secondary signs other than the interrupted duct sign for suspected hidden pancreatic malignancies gained importance [2, 4, 5].

This is a retrospective study focused on emphasizing useful tools to predict the presence of a hidden pancreatic karyogenetic mass in patients who don’t have a visible focal pancreatic lesion on CT, but present main pancreatic duct abrupt cutoff and dilatation.

The sample size comprised 92 patients from a CT database of a single large academic institution. The inclusion criteria were: abrupt cutoff of MPD associated with upstream dilatation, unidentified focal pancreatic lesion, histopathological confirmation or more than 2 years of stability on imaging surveillance. The exclusion criteria were: suboptimal image quality of CT and history of pancreatic surgery.

The following imaging findings were assessed: MPD cutoff site, parenchymal contour abnormality, maximum diameter of the MPD proximal to the duct cutoff site, presence of distal parenchymal atrophy, associated acute pancreatitis on CT and presence of pancreatic cystic lesions.

The clinical findings including new-onset diabetes mellitus (DM) and unintentional weight loss and laboratory findings including the serum level of carbohydrate antigen 19-9, amylase and lipase were also evaluated. After the histopathologic results or clinical follow-up, the sample was divided in two main groups: malignant (41,3%) and benign (58,7%).

Multivariable logistic regression analysis showed that CA19-9 elevation (odds ratio [OR] 7.5, 95% CI 2.0–28.6; p = 0.003), cutoff site at the head/neck (OR 7.6, 95% CI 1.8–32.3; p = 0.006), parenchymal contour abnormality at the duct cutoff site (OR 13.7, 95% CI 3.3–58.0; p < 0.001), and the presence of pancreatitis (OR 11.5, 95% CI 2.1–62.6; p = 0.005) were significant features for predicting the malignant group.

A combination of any two significant features showed an accuracy of 77.2%, and a combination of any three features exhibited a specificity of 100%. For predicting the probability of the malignant group, a CT-based nomogram was constructed based from the four significant features. This nomogram showed an area under the curve (AUC) of 0.84 (95% confidence interval [CI], 0.77–0.90). Therefore, a patient with three CT imaging features and CA19-9 elevation requires further diagnostic tests with aggressive management.

The authors acknowledge some limitations: its retrospective single-center design with a probable selection bias; the results are limited to the population of patients with MPD cutoff sign; histologic confirmation had only been achieved for seven patients in the benign group; the large portion of CT examinations in this study were not optimized for delineation of pancreatic abnormalities because most CT indications were unrelated to screening for PDAC, which might have lowered the sensitivity of each CT imaging feature; not performing an external analysis using an independent validation set to determine the thresholds for the ratios used to construct the nomogram; therefore, there is a need for further studies involving larger numbers of cases.

VICT2 Trait: Prognostic Alternative to Peritumoral Hepatobiliary Phase Hypointensity in HCC

Hanyu Jiang, Hong Wei, Ting Yang, Yun Qin, Yuanan Wu, Weixia Chen, Yujun Shi, Maxime Ronot, Mustafa R. Bashir, Bin Song

Radiology. 2023. DOI: 10.1148/radiol.221835

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, it has been recognized as a leading cause of death among patients with cirrhosis, and its incidence is expected to increase in the future [1].

MRI plays a key role in the management of HCC. To improve long-term survival in patients with HCC, in recent years several studies have been performed to detect imaging features with prognostic value.

Prior studies developed and validated preoperative models based on hepatobiliary (HBP) MRI features for predicting microvascular invasion (MVI) [2], which is one of the main histopathological factors associated with recurrence during the first 2 years after curative treatment [3]. Peritumoral hypointensity on HBP has been identified as the MRI feature most suggestive of MVI [4,5]. However, the assessment of peritumoral HBP hypointensity needs hepatobiliary contrast agent MRI, which is associated to some drawbacks, such as suboptimal arterial phase quality, higher cost, and deteriorated imaging quality in patients with conditions like cirrhosis or biliary obstruction.

To overcome these problems, Jiang and colleagues [6] have recently proposed an accurate non-hepatobiliary-specific imaging alternative to peritumoral HBP hypointensity named the “VICT2 trait”, including four non-hepatobiliary-specific MRI features:

1. Peritumoral portal venous phase (PVP) hypoenhancement;
2. Incomplete capsule;
3. Corona enhancement;
4. Peritumoral mild-moderate T2 hyperintensity.

By the application of the inclusion and exclusion criteria, this study enrolled 660 patients (551 males with a median age of 53 years) who underwent preoperative extracellular or hepatobiliary contrast-enhanced MRI for HCC assessment between December 2011 and November 2021. In this study, the most common etiology of the chronic liver disease was hepatitis B virus in 610 (92%) patients.

The predictive values of this non-hepatobiliary-specific MRI alternative for MVI and postoperative recurrence-free survival (RFS) were compared with peritumoral HBP hypointensity for patients with a solitary tumor with adequate documentation of the MVI status and follow-up information. The authors involved two liver pathologists who evaluated the margin resections by classifying tumors as positive or negative for MVI but they were aware of the clinical and imaging data. 

The preoperative MRI exams were analyzed retrospectively by two blinded abdominal radiologists which considered the “VICT2 trait” for each patient as positive when peritumoral PVP hypoenhancement was present or if all three other features were present or negative if these features are absent.

Univariate and multivariate logistic regression analysis was employed to determine the association between ECA/EOB features and MVI, and postoperative RFS was estimated by using the Kaplan-Meier curves.

Results demonstrate that both peritumoral HBP hypointensity (OR for MVI = 2.5, P = .02; hazard ratio for RFS = 2.5, P < .001) and the VICT2 trait (OR for MVI = 5.1, P < .001; hazard ratio for RFS = 2.3, P < .001) were significantly correlated to MVI and RFS. These values of the VICT2 trait were confirmed in the extracellular contrast agent group (OR for MVI = 4.0; hazard ratio for RFS = 1.7; both P < .001). Particularly, in the gadoxetate disodium-MRI group, the “VICT2 trait” showed a stronger association with MVI compared to peritumoral hypointensity on HBP. The study clinical impact suggests that “VICT2 trait”, identifying a high-risk area for MVI, could improve the preoperative management of patients with hepatocellular carcinoma for the selection of appropriate medical and/or surgical therapy.

Radiologic-Pathologic Correlation of Hepatobiliary Phase Hypointense Nodules without Arterial Phase Hyperenhancement at Gadoxetic Acid–enhanced MRI: A Multicenter Study.

Ijin Joo, So Yeon Kim, Tae Wook Kang, Young Kon Kim, Beom Jin Park, Yoon Jin Lee, Joon-Il Choi, Chang-Hee Lee, Hee Sun Park, Kyoungbun Lee, Haeryoung Kim, Eunsil Yu, Hyo Jeong Kang, Sang Yun Ha, Joo Young Kim, Soomin Ahn, Eun Sun Jung, Baek-Hui Kim, Hye Seung Han, Jeong Min Lee.

Radiology 2020 Aug;296(2):335-345. doi: 10.1148/radiol.2020192275. Epub 2020 Jun 2.

Introduction
Current guidelines for hepatocellular carcinoma (HCC) [1] include gadoxetic acid-enhanced magnetic resonance imaging (MRI) as a first line imaging modality, due to its high sensitivity in the assessment of vascular changes and the possibility to acquire the hepatobiliary phase [2]. 

As already established, HCC develops by a multistep carcinogenesis process from low- to high-grade dysplastic nodules to early and progressed HCC [3]; since the expression of the cellular transporter responsible for the uptake gadoxetic acid in hepatocytes starts to decrease earlier than the arterial changes causing arterial phase hyperenhancement (APHE), hepato-biliary phase (HBP) hypointense nodules without APHE are proposed as HCC precursors as early HCC or high grade dysplastic nodule[3].

As the presence of APHE is a major feature in HCC diagnosis in most guidelines [1, 4], HBP hypointense nodules without APHE are considered as “probably HCC”; in several studies these nodules are associated with hypervascular transformation and poor prognosis after curative treatment for HCC [5, 6].

In view of the different management of HCC and early HCC versus dysplastic premalignant nodules and considering the possibility of non-invasive treatments [7], being able to differentiate these nodules may have an important clinical value.

Discussion
This retrospective multicenter study aimed to evaluate the pathologic diagnosis of HBP hypointense nodules at gadoxetic acid-enhanced MRI without APHE in a large patient cohort from eight institutions, aiming at determining significant imaging and clinical features.

The authors final enrollment sample included 334 nodules in 298 patients with cirrhosis or chronic liver disease with Child Pugh A-B liver function, who underwent gadoxetic acid-enahnced MRI within 3 months from the histologic diagnosis. Included nodules were of 30 mm or smaller in diameter, since early HCCs and non-malignant cirrhosis associated nodules are rarely larger than 30 mm [8] and the size cited is generally a suitable indication for local ablation.

The authors involved ten pathologists who retrospectively evaluated the histologic specimens and gave the final diagnosis of regenerative nodule, low or high grade dysplastic nodule, HCC foci in dysplastic nodule, early or progressed HCC. A consensus was considered if more than five pathologists agreed on one category or after performing a second round of pathologic review to achieve consensus.

The results of the study showed that 44% of HBP hypointense without APHE nodules were progressed HCC, 20.4% were HCC foci in dysplastic nodules or early HCC, 27.5% were high grade dysplastic nodules, and 8.1% were low grade dysplastic or regenerative nodules.

Multivariable analysis found imaging and clinical features associated with progressed HCC that could help distinguish from lower grade nodules, such as well defined margins, hypointensity on T1 weighted images, intermediate signal intensity on T2 weighted images, washout in portal phase, and restricted diffusion(odds ratios 5.5, 3.2, 3.4, 1.9 respectively; P values .03, .001, .001, and .04 respectively)  and a-fetoprotein level > 100 ng/mL (odds ratio 2.7; P value .01).

Transient severe motion artifacts on gadoxetic acid–enhanced MRI: risk factor analysis in 2230 patients.

Eun Bee Jang, Dong Wook Kim, Sang Hyun Choi, Seung Baek Hong, Taeyong Park, Yousun Ko, Su Jung Ham.

European Radiology (2022) 32:8629–8638. https://doi.org/10.1007/s00330-022-08885-2

Gadoxetic acid is a contrast agent used in MRI liver imaging. However, the appearance of the transient severe motion artifact (TSM) during the arterial phase may limit its use.

The authors analyzed retrospectively the risk factors involved in the appearance of this artifact and its relationship with gadoxetic acid in a large cohort. After applying the inclusion and exclusion criteria, 2230 patients who underwent a MRI at tertiary centre between January 2017 and June 2017 were selected. 

Inclusion criteria included: age over or equal to 18 years and have a MRI done between January 2017 and June 2017. Exclusion criteria included: absence of laboratory data or anthropometric measurements for at least one month prior to the test. 

The clinical information was obtained from the electronic database: demographic data, laboratory data, underlying disease, ascites and pleural effusion, and previous gadoxetic acid–enhanced MRI studies.

The degree of ascites and pleural effusion was analysed on the MRI examination.

Two board-certified radiologists evaluated TSM artifact on arterial phase images in gadoxetic acid-enhanced MRI using a 5-point grading scale. According to the severity of the artifact, patients were classified into two groups:

1.  non-TSM group, includes artifact grade of 0 to 3:  grade 1 or no artifact, grade 2 or minimal artifact and grade 3 or moderate artifact with some effect on diagnostic quality.

2.  TSM group, includes artifact grade of 4 or 5: grade 4, severe artifact that affects diagnostic quality but still interpretable. Finally grade 5 which consisted of extensive artifact with non-diagnostic images. 

The incidence of TSM using gadoxetic acid enhanced MRI was 5.0% (111/2230 examinations). Univariable and multivariable logistic regression analyses were performed obtaining the following results:

-The risk factors such as old age (≥ 65 years) [OR = 2,01 (1,31–3,07)], High Body Mass Index (BMI ≥ 25 kg/m2) [OR = 1,76 (1,18–2,63)], chronic obstructive pulmonary disease (COPD) [OR = 6,11 (2,32–16,04)], and moderate to severe pleural effusion [OR = 3,55 (1,65–7,65)], were recognized as significant independent risk factors for TSM occurrence.

-Hepatitis B and previous gadoxetic acid–enhanced MRI studies was associated with a lower risk of TSM occurrence, [OR = 0,66 (0,43–0,99)] and [OR = 0,52 (0,33–0,83)], respectively. In this study, hepatitis B was an independent negative risk factor probably because these patients have previous MRI studies and some of them do not have advanced cirrhosis.

Based on risk factors (age > 65 years, BMI > 25 kg/m2, COPD, moderate to severe pleural effusion, no hepatitis B, and no previous experience of gadoxetic acid), the predictive risk of TSM was 0,6% in the absence of risk factors,5,7% if at least one of the significant factors was present, and this percentage increased to 16,3% with at least four risk factors.

In addition to the current study, many of these patients underwent examinations with an extracellular contrast agent within 1 year (138/2230).  This fact allowed the authors of the study to create a subgroup analysis to compare the incidence of TSM with hepatospecific and extracellular contrast agent. The incidence of the TSM was higher with gadoxetic acid-enhanced MRI (McNemar test:  9,5% vs 2,2%, p =0,006).

The authors acknowledge the following limitations: selection bias due to retrospective study design, studies obtained from Korean institutions where the hepatitis B virus is endemic and low incidence (5%) compared with previous meta-analysis (13%).    

Clinical, Imaging, and Pathologic Features of Conditions with Combined Esophageal and Cutaneous Manifestations.

Matthew H. Lee, MD, Meghan G. Lubner, MD, J. Klint Peebles, MD, Molly A. Hinshaw, MD, Christine O. Menias, MD, Marc S. Levine, MD, Perry J. Pickhardt, MD

RadioGraphics 39:1411–1434. Published Online: Aug 16 2019

The esophagus, consists of squamous epithelial cells, similar to what composes the skin. As a result, these two separate organs are linked through a concomitant affliction by diseases ranging from infections, autoinflammatory and autoimmune conditions to genetic syndromes and paraneoplastic manifestations. Each such disorder may present with characteristic findings on either the skin or/and the esophagus, thus providing a certain diagnostic direction.

The present study seeks to bring those different entities under a converging scope of clinical presentations and imaging observations with the aim to provide the reader with the tools to assert the underlying etiologic factor.

The infectious organisms studied here are HSV, CMV, HIV and Candida albicans. Multiple, lesser-sized esophageal ulcers are typical of HSV, whereas larger lesions are more characteristic of CMV and HIV infections. C. albicans assumes a linear, plaque-like appearance on the esophagography. Regarding the skin, HSV features clustered blisters; CMV exhibits non-distinct traits, C. albicans presents the characteristic white plaques of oral thrush, whereas, HIV-infection, defined by its immunodefective nature and concurrent opportunistic infections can assume any of the aforementioned skin lesions [1], [2], [3].

Moving on to bullous diseases, two categories are described, namely the epidermolysis bullosa  (EB) and the pemphigoid disorders (PD). The former concerns a group of genetic conditions that affect the epidermis and mucosa, weakening their structural integrity, making them susceptible to mechanical damage [4]. The latter targets the subepidermis and mucosa in the form of autoimmunity, can affect any part of the soma and presents as pruritic or painful vesicular lesions. On regard to esophageal involvement, both entities may cause strictures of the esophagus, with EB most commonly affecting its upper anatomic area, whereas PD any part of it [5].

In direct contrast, scleroderma, another autoimmune disease, mostly affects the distal part of the esophagus, reducing its motility, causing it to dilate early on, though also effecting strictures later on the course of the disease. The skin of the extremities seems to be damaged first, becoming rigid and prone to trauma [6].

The autoinflammatory conditions studied here are lichen planus and Crohn’s disease. Lichen planus is allegedly a T-cell oriented disease that causes lilac-coloured papules on the skin, while also involving the nails and hair. The esophagus, mainly its thoracic part, reduces in diameter [7] and can pose a differential bipolar, having a similar esophagographic appearance to eosinophilic esophagitis. The elder of age and female sex predominant on lichen planus in contrast to a younger male patient on eosinophilic esophagitis help differentiate between the two. Crohn’s disease, a primarily bowel disorder, may affect the skin via perianal fissures and fistulas or indirectly via its implications on nutrient absorption. The esophagus is not usually a trademark organ of this disease, but it may manifest with small ulcerative lesions or fistulas to adjacent organs [8].

Cowden syndrome consists a genetic disorder of a defective tumour suppressor gene that results in an increase in hamartomas and malignancy. Related skin conditions are hair follicle-derived hamartomas, fibromas and papules on the acral dorsal parts. The esophagus is infrequently affected, but may present with a nodule-like appearance at the esophagography [9]. Blue Rubber Bleb Nevus Syndrome (BRBNS) is a congenital disorder with a mutated endothelial cell receptor and resulting venous malformations both on the skin and the GI tract, in the form of polyps or even mass-like configurations [10].

Melanoma constitutes a primary malignant tumour of melanocytes, presents as uneven, varicoloured, growing skin lesion that has rarely an impact on the esophagus but can, nonetheless, affect it as a non-obstructive, but lumen-expanding polypoid mass [11]. Acrokeratosis paraneoplastica comprises a paraneoplastic condition, often of an SCC, of the respiratory and/or the GI tract. Its varying skin lesions can direct to a primary neoplastic or secondary disseminated foci. An SCC of the esophagus can assume a plaque or polypoid lesion morphology early on or a mass-like form that causes narrowing of the esophageal lumen at later stages [12].

Influence of dilution on arterial-phase artifacts and signal intensity on gadoxetic acid–enhanced liver MRI.

Sarah Poetter-Lang, Gregor O. Dovjak, Alina Messner, Raphael Ambros, Stephan H. Polanec, Pascal A. T. Baltzer, Antonia Kristic, Alexander Herold, Jacqueline C. Hodge, Michael Weber, Nina Bastati, Ahmed Ba-Ssalamah

European Radiology, volume 33, pages 523–534 (2023)

MRI with gadoxetic acid is widely and increasingly used to detect and characterize focal liver lesions. (1) However, one of the main limitations of gadoxetic acid is represented by arterial-phase (AP) artifacts: transient severe motion (TSM) and truncation artifacts. Both are due to the acute fleeting peak of gadoxetic acid blood plasma concentration, which causes acute transient dyspnea by activating central chemoreceptors,  and the rapid disappearance of contrast from the imaging field. (2,3). The acute fleeting peak plasma gadoxetic acid concentration during the arterial phase can be prevented by saline dilution of gadoxetic acid at 1:1 and a slow injection rate of 1 ml/s (4), both off-label. The Authors’ aim was to assess the effect of these two strategies on AP artifacts reduction, on quantitative differences in signal intensity (SI), signal-to-norm, and contrast-to-norm, and hence focal lesion conspicuity on MR imaging.

This single-center retrospective study enrolled 112 patients who had undergone at least one non-diluted (ND) and one saline-diluted (D) gadoxetic acid–enhanced MRI at 1 ml/s for known or suspected liver or pancreaticobiliary diseases between December 2010 and July 2017. Patients who had undergone liver transplantation between the two MRIs or who had artifacts in all sequences were excluded.

Arterial-phase imaging was initiated at the individual patient’s t-peak, timed using a test bolus technique. Two blinded radiologists independently graded on a 5-point scale the presence of artifacts in dynamic T1-weighted sequences (unenhanced, arterial, portal venous, transitional, and 20-min HB phases). AP artifacts were defined as a score ≥ 4 in the arterial phase.(2) Then, quantitative signal intensity (SI) measurements were acquired by drawing regions of interest (ROI) at the level of the celiac trunk in five locations: aorta, portal vein, liver parenchyma, focal liver lesion, and paraspinal muscle in all phases in each patient. The SI value was normalized to the SI of the paraspinal muscle to obtain signal-to-norm ratio (SI_Norm). For focal lesions, the contrast-to-norm ratio (C_norm) was also calculated.

AP artifacts were significantly reduced with dilution and were present in 35 (31%) of the non-diluted exams compared to 10 of the diluted exams (9%). An artifact severity score of 5 (i.e. nondiagnostic exam) was assigned to 18 exams (16%), 17 of which were in the non-diluted group. The scored severity of the artifacts was significantly higher in the ND compared to the D protocol (p < 0.001).

The mean absolute liver parenchyma SI and mean liver SI_Norm were significantly higher in the diluted exams in all contrast-enhanced phases. The mean Si_Norm of the aorta in the AP and of the portal vein in the portal venous phase was significantly higher in the D exams (p = 0.005 and p = 0.035, respectively). There was no significant difference in the C_Norm of all lesions (FNH, metastases, cirrhotic nodules, adenomas, hemangiomas) combined for D versus ND exams (all phases p > 0.05). Evaluation for lesion subtype, when n ≥ 10 (i.e., FNH and metastases), also revealed no significant difference in C_Norm between the ND and D exams (all phases p > 0.05).

Arterial-phase artifacts did not have a significant influence on the SI of liver parenchyma on the ND (p=0.627) and on D (p=0.644) exams. The higher SI and SI_Norm in the diluted exams were attributed to contrast dilution and slower injection rate. In order to assess the effect of artifacts on lesion visibility, the authors also analyzed the detectability of lesions smaller than 1 cm. They were able to detect 5 more lesions and to see 3 lesions better on the diluted vs non-diluted scans. They attributed these findings to TSM artifact reduction as truncation artifacts did not influence the visibility of these lesions.

The high relaxivity of gadoxetic acid explains why the difference in SI and SI_Norm was largest in the HBP. Also,  during recirculation, on the diluted exams hepatocyte transporters had more time to accumulate gadoxetic acid due to doubling the volume on the diluted exams.

Liver stiffness measurement by magnetic resonance elastography is not affected by hepatic steatosis.

Jie Chen, Alina M. Allen, Terry M. Therneau, Jun Chen, Jiahui Li, Safa Hoodeshenas, Jingbiao Chen, Xin Lu, Zheng Zhu, Sudhakar K. Venkatesh, Bin Song, Richard L. Ehman, Meng Yin

European Radiology (2022) 32:950–958

Magnetic resonance elastography (MRE) is an excellent tool for the non-invasive detection of liver fibrosis. [1] It quantitatively evaluates liver stiffness (LS) and is increasingly demanded in clinical routine. This diagnostic technique can be performed using additionally hard- and software representing an objective, reliable and reproducible method without significant variability across vendors and magnetic field strengths. [2]

Continuous acoustic waves generated by an active driver induce a tissue stimulation; with a phase contrast sequence the propagating waves are visualized and then automatically converted into quantitative sectional images so-called elastograms. [3] Typical and recommended parameters of either GRE or SE-EPI MRE performed sequences are listed in the regularly updated QIBA profile. [4] Usually four axial slices are taken through the liver in different positions. The image evaluation takes place on the 95% confidence maps, considering the wave and magnitude images. In the liver, partially automatically, an as large as possible or several subcapsular regions of interest (ROIs) are drawn. [5] Finally, the MRE result (specification in kPa, SI unit for pressure/mechanical stress) is an indication of the fibrosis score, from F0 (no fibrosis) to F4 (cirrhosis). [6] The interpretation of MRE results should always consider the clinical context, as MRE assessment of liver fibrosis may be affected by other pathologic changes as inflammation, passive congestion, biliary obstruction, or diffuse infiltrative disorders which may also increase liver stiffness values. [1; 7]

In diffuse liver disease, steatosis is an important entity, representing the most common form of diffuse liver disease. With a worldwide prevalence of 25-45% nonalcoholic fatty liver disease (NAFLD) has become a medical burden. [8] Patients with NAFLD can progress to liver fibrosis or even cirrhosis. It is of great clinical relevance among all NAFLD patients, to non-invasively differentiate those with non-alcoholic steatohepatitis (NASH) and advanced fibrosis, as these have the greatest risk of developing liver-related increased morbidity and mortality.

The authors of the present retrospective study aimed to evaluate the relationship between pathology-assessed hepatic steatosis, MR-measured proton density fat-fraction (PDFF), and MRE-gaged liver stiffness in a large patient cohort with biopsy-proven or high risk of NAFLD.  The study focuses on the impact of hepatic steatosis/liver fat on liver stiffness measurement (LSM).

256 patients with liver biopsy and MRI/MRE examination carried out within one year were included. The MRI protocol was performed on a 1.5T device and consisted of a 2-point or 6-point Dixon to estimate the PDFF and of a 2D MRE to measure the LS. NAFLD was defined by imaging or histology.

The PDFF correlated significantly with steatosis grades. An excellent correlation (r = 0.97, p < 0.001) was found in 87 patients. Age, fibrosis stage and biopsy-based steatosis were significant covariates influencing the LS. Patients without histopathologic steatosis showed significant lower LS as patients with steatosis but no significant difference of LS was found between the different degrees of steatosis severity. Finally, no statistically significant relationship between LS and PDFF could be confirmed.

The results indicate that the severity of hepatic steatosis in patients with NAFLD, as assessed quantitatively with MRI-PDFF methods, does not have a significant effect on MRE-assessed LS. Steatosis is therefore not a relevant variable in the setting of MRE measurements. This observation is consistent with other publications in which no or only little effect of the severity of hepatic steatosis on MRE was found. [9]

The authors further hypothesize that the apparent correlation between LS and hepatic steatosis, that is reported in literature [10], could be linked to other histopathologic processes as inflammation.

Transjugular intrahepatic portosystemic shunt (TIPS) complications: what diagnostic radiologists should know.

Giuseppe Mamone, Mariapina Milazz, Ambra Di Piazza, Settimo Caruso, Vincenzo Carollo,  Giovanni Gentile, Francesca Crinò, Gianluca Marrone, Gianvincenzo Sparacia, Luigi Maruzzelli, Roberto Miraglia

Abdominal Radiology (2022) doi: 10.1007/s00261-022-03685-0

Transjugular intrahepatic portosystemic shunt (TIPS) is a recognized treatment for the complications of portal hypertension. Morbidity has been shown to be as high as 20% (1) with complications having a 2% fatality rate (2). Early identification of complications have a favorable outcome. The authors provide a review to outline the role of diagnostic radiology in identifying and assessing post-TIPS complications.

CT, MRI and Doppler US all have a role in the pre-procedural evaluation of hepatic and portal vein patency as well as important anatomical variations. Liver morphology, masses and cysts should all be documented as these may interfere with the technical success of the procedure. Obstructed bile ducts should be identified as they require pre procedure decompression.

The authors identify two categories of complications: those related to interventional technique (e.g. hepatic vein thrombosis, haemorrhage, ischaemia, vascular or biliary injury, stent malpositioning or migration) and those associated with TIPS dysfunction and the portosystemic shunting effect.

Correct stent position is of prime importance to achieve adequate function and patency. Stent malpositioning can cause perfusion and shunt outflow stenosis (1). Stent migration can lead to a myriad of cardiovascular complications (1). Covered stents have a higher tendency for migration on comparison to bare metal stents (1). Stent position can be assessed by US, CT and MRI, with the proximal end sited at the confluence of the portal vein and the liver parenchymal tract.

Accidental perforation of the hepatic artery or a branch occurs in 1 to 6% of patients (1, 3). This is usually of low clinical significance (1). Multiphase contrast enhanced CT can be utilized to detect potential complications including pseudoaneurysm, vascular dissection or occlusion and arterioportal fistula haemorrhage. 

Portal vein injury on the other hand, has been considered the riskiest step in a TIPS procedure (4) as it can result in massive haemorrhage. Clear understanding of the vascular anatomy with pre-procedural imaging is of prime importance. This is treated immediately by the interventional radiologist, however post-procedure CT or MRI are useful for visualizing residual perihepatic haemorrhage. Haematoma appears as hyperdense on CT and hyperintense on T1, with no contrast enhancement. (4)

Portal and hepatic vein thrombosis appear as non-enhancing vessels on contrast enhanced CT or MRI, with absence of flow at colour doppler examination. Hepatic vein thrombosis is usually of little clinical consequence (5), however a Budd-Chiari type hepatic ischaemia and acute hepatic failure can result.

Biliary duct puncture is reported in up to 5% of cases (1, 3). The connection between biliary and vascular systems can result in infection and haemobilia (1). TIPS stents can also generate biliary occlusion (6) and rapid hepatic decompensation (7).  Segmental cholestasis, with intrahepatic biliary dilatation can be seen on imaging. MRI and MRCP is the best way to evaluate cholangitis. Classic findings of a hepatic abscess are the double target sign on contrast enhanced CT: caused by a central low attenuation lesion surrounded by an enhancing rim and a low density outer ring (oedema) (8).

The incidence of liver ischaemia is thought to be underestimated imaging is only performed when complications occur. Infarcts are rare due to the dual blood supply. CT show the parenchymal ischaemic injury as a hypodense, non-enhancing area without mass effect which is often peripheral and wedge shaped.

Puncture of non-target organs, most commonly gallbladder (1), is another known complication.

TIPS dysfunction is defined as a reduction in the portal venous decompression due to occlusion or stenosis of the shunt. Follow up with doppler US is the method to identify such complications, with the initial baseline examination performed 7-14 days post-procedure.

Stenosis and occlusion are the most frequent complications, with long term patency of ePTFE covered stents having favorable outcomes on comparison to bare metal stents: dysfunction at 2 years of 20-30% as compared to 60-80% respectively (9).

Emerging imaging techniques for acute pancreatitis

Saeed Ghandili, Shahab Shayesteh, Daniel F. Fouladi, Alejandra Blanco, Linda C. Chu

Abdom Radiol (NY). 2020 May;45(5):1299-1307.
doi: 10.1007/s00261-019-02192-z.

Acute pancreatitis (AP) is caused by acute inflammation of the pancreas and adjacent tissue. Current CT and MRI evaluation of AP, included in the revised Atlanta classification of AP, is based on morphologic imaging criteria [1].

Authors suggest that newer MR techniques such as diffusion-weighted imaging (DWI), T1 and T2 mapping can offer quantitative imaging features. DWI is a MR imaging technique that quantifies the diffusion of water molecules within biologic tissues. In AP, pancreatic inflammation and tissue injury restrict diffusion, therefore, the ADC (apparent diffusion coefficient) of AP has been reported to be significantly lower than that of normal pancreas [2,3]. Lower ADC values were also associated with increased severity of AP. DWI is also potentially useful in diagnosing necrotizing pancreatitis, as ADC values have been found to be significantly higher [4]. Finally, DWI has shown incremental value in identifying superimposed infection in pancreatic fluid collections, which have more restricted diffusion and lower ADC values relative to sterile collections [5].

Pancreatic disease states such as edema increase T1 relaxation time and decrease the signal intensity on T1-weighted images. The T1 relaxation time cannot be directly measured on traditional T1-weighted image. On the other hand, T1 mapping directly measures the T1 relaxation time of the region of interest, facilitates comparison of T1 relaxation time of patients with different pancreatic pathologies and allows serial assessment of T1 relaxation time to monitor disease progression and response to treatment, with a single breath hold [6]. Several studies performed at 3T have shown increased T1 relaxation time for patients with chronic pancreatitis (CP) and autoimmune pancreatitis (AIP) compared to normal controls. While there are no currently published reports detailing alterations in T1 relaxation time in patients with AP, based on these preliminary results, one would expect that T1 relaxation time should also be elevated in patients with AP. This needs to be validated in future studies.

Similar to T1 mapping, T2 mapping is a technique that can quantify the transverse relaxation time. Pancreatic edema and inflammatory changes in AP typically account for the observed increased signal intensity on T2-weighted images. T2 mapping offers the potential to quantify the degree of pancreatic edema and inflammatory changes, which may provide diagnostic and prognostic information [7]. A series of preliminary studies, by Vietti Violi et al. etc, showed that T2 mapping may provide quantitative biomarkers indicative of underlying pancreatic disease. These results need to be validated in future studies.

Advances in image post-processing and analytic techniques also offer opportunities for improved disease detection and classification. Both radiomics and artificial neural networks take advantage of the high-dimensional mineable data present in medical images. There is growing evidence that radiomics may provide useful imaging biomarkers for pancreatic tumor detection. A few studies have applied similar radiomics approaches to extract additional diagnostic and prognostic information in patients with AP. Lin et al. reported that contrast-enhanced MRI-based radiomics features were predictive of AP severity in a retrospective study of 259 patients with AP [8]. The results showed that the radiomics model was able to more accurately predict severity of AP in the early stage compared to some of the existing clinical models, as well as, predict complications related to AP, or recurrent episodes of AP.

Another emerging technology that has the potential to improve risk stratification and management in AP is the artificial neural network (ANN). ANNs pass the input values through a number of “hidden layers” of mathematical equations to develop a model that best fits the data. Most of the current literature on ANNs and AP focuses solely on clinical and laboratory data as input, while only one study by Keogan et al. incorporated both radiologic and laboratory data [9]. No published reports have directly used ANNs to extract quantitative imaging features from AP, however, there have been several recent exciting developments in applying ANNs to detect pancreatic ductal adenocarcinoma, which may be translatable to AP.

Systematic review and meta-analysis of MRI features for differentiating autoimmune pancreatitis from pancreatic adenocarcinoma

Seung Bae Yoon, Tae Yeon Jeon, Sung-Hoon Moon, Sang Min Lee, Myung-Hwan Kim.

European Radiology (2022) 32:6691–6701

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that need to be differentiated from other types of pancreatitis such as alcoholic, hereditary or obstructive [1, 2]. Nowadays it is known that this condition has an autoimmune etiology and is not limited to the pancreas alone, but also involves organs such as bile ducts, retroperitoneum, and lymph nodes [3].

Further histological and clinical profiling of AIP revealed 2 distinct types: type 1, histological descripted as lymphoplasmacytic sclerosing pancreatitis (LPSP); and type 2, called idiopathic duct-centric pancreatitis (IDCP). Both share some histopathological features, such as periductal lymphoplasmacytic infiltrate and storiform fibrosis. A characteristic histopathologic finding of IDCP is granulocyte epithelial lesions. Instead, LPSP can lead to venulitis, with lymphocytes and plasmacells, often leading to obliteration of the affected veins, and is associated with either serum IgG4 elevation and with other organ involvement.

Extrapancreatic involvement of IDCP, reported approximately 30% of cases, is with inflammatory bowel disease.

The most frequent presentation of AIP is obstructive jaundice and/or pancreatic mass. Whereas most patients have pancreatic swelling (diffuse or focal), a few patients may show low-density pancreatic masses. The diagnosis of LPSP is made through a combination of imaging, serologic and clinical findings, making histological confirmation not mandatory. Contrarywise, since IDCP patients are seronegative and lack other organ involvement, definitive histological diagnosis is needed [4]. Both conditions respond to steroid therapy and do not need surgery [5].

The differential diagnosis with pancreatic ductal adenocarcinoma (PDAC) is challenging, especially for focal-type AIP, due to de clinical manifestations and radiological features.

A recent systematic review and meta-analysis conducted by Yoon and colleagues aimed to identify MRI features that will aid the differential diagnosis between AIP and PDAC. After an initial screening or 1214 studies, the authors included 12 retrospective studies published between January 2006 and July 2021. After reviewing 92 overlapping descriptors of MRI findings in the included studies, 16 MRI features were selected:

• Ten favoring AIP: diffuse enlargement, capsule-like rim, multiple main pancreatic duct (MPD) strictures, homogeneous delayed enhancement, low apparent diffusion coefficient value, speckled enhancement, multiples pancreatic masses, tapered narrowing of MPD, penetrating duct sign, and delayed enhancement.
• Six favoring PDAC: target type enhancement, discrete pancreatic mass, upstream MPD dilatation, peripancreatic fat infiltration, upstream parenchymal atrophy, and vascular involvement.

From these features, the pooled diagnostic accuracy, including the diagnostic odds ratios (DORs) with 95% confidence intervals (CIs), was calculated using a bivariate random effects model. MRI features for AIP tended towards a high specificity but low sensitivity. Among them, diffuse enlargement, capsule-like rim, multiple MPD strictures, and homogeneous delayed enhancement had the highest DORs, and showed a high pooled specificities (90–100%). Diffuse enlargement had the highest DOR; however, diffuse-type AIP can be differentiated from PDAC due to the growing awareness of imaging appearance of AIP [6]. Radiologists must be aware that pancreatic lymphoma, diffuse PDAC, or metastasis to the pancreas can also present with diffuse enlargement of the pancreas [7-8]. The capsule-like rim, representing a continuous halo-like soft tissue lesion surrounding the pancreas can be thin or thick depending on disease activity [9]. Multiple pancreatic masses and MPD strictures without intervening duct dilatation are especially helpful in the differentiation of focal-type AIP from PDAC. Delayed enhancement had low specificity compared to the “homogeneous” delayed enhancement (55% vs. 90%). Due to its desmoplastic nature, PDAC can show delayed enhancement. However, radiologists should consider the presence of homogenous enhancement when evaluating the enhancement pattern of a focal pancreatic mass in the differential diagnosis between AIP and PDAC. Penetrating duct sign has a high sensitivity (81%) and is indicative of AIP.

Identifying high-risk colon cancer on CT an a radiomics signature improve radiologist’s performance for T staging?

Eun Kyoung Hong, Zuhir Bodalal, Federica Landolf, Nino Bogveradze, Paula Bos, Sae Jin Park, Jeong Min Lee, Regina Beets-Tan

Abdominal Radiology (2022) 47:2739–2746.

Colon cancer is the third most common malignancy and the fourth most common cause of cancer-related death [1]. Accurate staging and identification of high-risk colon cancer is crucial to avoid overtreatment and unnecessary exposure of low-risk patients to higher morbidity of surgical resection after preoperative treatment [2]. Based on published works, radiomics can provide us with quantitative imaging information to describe the comprehensive morphological features of the tumor, which can help and guide clinicians [1, 2, 3, 4]. Regarding the role of radiomics in colon cancer, most studies have investigated the role in terms of survival, lymph node metastasis, and molecular/genetic subtype prediction. Not much is known about radiomics application in risk stratification for colon cancer [2, 4, 5].

The aim of this retrospective study [2] was, firstly, to assess the additional value of radiomics features that were automatically extracted from pre-operative colon cancer CT in distinguishing high-risk colon cancer patients. Secondly, the purpose was to develop a combined model integrating both radiomic and conventional CT staging features for the prediction of high-risk colon cancer.

The authors used a sample of 292 patients (205 from Seoul National University Hospital and 87 from Netherlands Cancer Institute) with colon cancer (85 patients with ≤ T2 and 207 patients with ≥ T3 primary tumor) who received surgical resection and with pre-operative imaging within 60 days of surgery. Exclusion criteria were: neoadjuvant therapy, inadequate pathologic data, multiple primary tumors, non-visible tumor on CT, and poor quality CT. The radiologists noted the presence of the tumor beyond the muscularis propria layer of tumors (cT3-T4), blinded by all the clinical and histological information. Further, 6048 radiomic features were automatically extracted, and after applying an unsupervised dimensionality reduction technique, orthogonal principal feature analysis, only 29 features were selected and included for further analysis.

Univariate and multivariate logistic regression analysis was performed to determine the significant association between imaging features, CT staging and pathologic staging of colon cancer in differentiating tumor staging ≤ T2 vs.  ≥ T3. Afterwards, using logistic regression, elastic net regularization and 10-fold cross validation, the authors developed different predictive models for each outcome. ROC curve analysis was conducted and area under the curve (AUC) with DeLong confidence interval (CI) was calculated to evaluate the performance of each model.

Results show that radiologist’s performance in CT staging of colon cancer was significantly associated with high pT tumors from both univariate (OR = 6.16, p < 0.001) and multivariate (OR = 1.22, p < 0.001) logistic regression analysis. The AUC value of CT staging was 0.697 (95% CI 0.638-0.756). Moreover, when radiomic features were added to the model, AUC increased to 0.779 (95% CI 0.720-0.839). From the 10-fold cross-validation, CT staging demonstrated AUC of 0.628 (95% CI 0.558-0.689) and increased to 0.727 (95% CI 0.621-0.777) when radiomic features were included.

These results of this study show that CT radiomic features could improve the radiologist’s performance in T staging colon cancer on CT, and using the combined model using both CT staging and radiomic features demonstrated significantly better diagnostic performance [2]. But, the integration of these combined models and radiomic scores in a clinical validation stage would require extensive multicenter prospective studies to prove their generalizability.

Neoadjuvant chemotherapy for locally advanced colon cancer remains an evolving treatment paradigm [6]. The FOxTROT trial, an international randomized controlled trial of 1052 patients evaluating neoadjuvant chemotherapy for colon cancer, used CT as a reliable tool for stratifying high-risk patients. The trial reported that 98% of patients undergoing neoadjuvant chemotherapy underwent surgery compared with 99% of patients who did not have neoadjuvant treatment, a reassuringly similar rate [7].

CT is already a routine part of preoperative staging of colon cancer, but in the context of documenting extracolonic disease [6]. A meta-analysis reported a sensitivity of 90%, and specificity of 69%, in differentiating stage T3 and T4 tumors on CT [8], which currently serves as the major selection criteria for patients with high-risk colon tumors who will receive neoadjuvant chemotherapy [9].

In conclusion, accurate pre-surgical staging of colon cancer is crucial for pre-operative chemotherapy, but the addition of radiomics/artificial intelligence approaches can help to build models that hold significant promise for integrated diagnosis and clinical decision making.

MRI follow‑up for pancreatic intraductal papillary mucinous neoplasm: an ultrashort versus long protocol

Johansson K, Mustonen H, Nieminen H, Haglund C, Lehtimäki TE, Seppänen H.

Abdom Radiol (NY). 2022 Feb;47(2):727-737. doi: 10.1007/s00261-021-03382-4.

Intraductal papillary mucinous neoplasms (IPMNs) are mucin-producing tumors that arise from the pancreatic duct and are considered precursor lesions to pancreatic cancer [1]. There are three types of IPMNs differentiated based on morphologic differences.

with different risk profiles for malignant transformation. The Main duct IPMNs (MD-IPMN) are characterized by involvement with the main pancreatic duct (MPD) and identified by a dilated MPD (5 mm) without an associated cyst or other cause for ductal obstruction. Branch duct IPMNs (BD-IPMN) arise from a branch of the MPD and are identified as unilocular or multilocular pancreatic cysts with communication with the MPD, which measures <5 mm. Mixed-type IPMNs (MT-IPMN) meet the criteria for both MD and BD IPMNs [2].

Given that approximately an average of 8% of all pancreatic cancers arise from these lesions, IPMN follow-up offers an opportunity for early cancer detection [3]. Most IPMNs are accidentally detected when abdominal imaging is performed for another indication, as they are mostly asymptomatic. The presence of some clinical symptoms, such as abdominal pain or bloating, has been associated with malignant transformation in patients with IPMNs [4, 5].  Abdominal MR and MR cholangiopancreatography (MRCP) is the investigation of choice for initial characterization and follow-up of IPMN, thanks to its high contrast and spatial resolution and lack of ionizing radiation. However, MR examinations suffer from long acquisition time and, the spreading of MR short and ultra-short protocols is reaching interest also in IPMNs follow-up; however, the possibility to optimize MR protocols for IPMNs follow-up needs to be investigated [6].

The authors of the present study aimed to assess whether an MR ultrashort magnetic protocol (USP) that includes only axial T2-weighted half-Fourier single-shot turbo spin-echo (HASTE) sequences and 3D MRCP sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences is comparable in terms of diagnostic accuracy with longer protocols in the identification of worrisome features (WF) and high-risk stigmata (HRS) and, in the measurement of the major diameter of the largest cyst and main pancreatic duct (MPD). Reductions in cost and time related to USP were also assessed.

This retrospective study included a final population of 112 surveillance patients evaluated for pancreatic cysts at Helsinki University Hospital who underwent examination with 1.5 Tesla MRI. Three MRI datasets were analyzed including USP as abovementioned then, long protocol (LP) including axial T2-weighted HASTE with and without fat saturation (fs), thin and thick coronal T2-weighted HASTE fs, axial T1-weighted fast low angle shot (FLASH) fs, axial T1-weighted in/opposed phase, T2-weighted 3D MRCP SPACE and maximum intensity projection (MIP) reconstruction, diffusion-weighted imaging (DWI), and T1-weighted fs volumetric interpolated breath-hold (VIBE) before and after the administration of the contrast agent; and, finally short protocol (SP) including axial T2-weighted HASTE, thin and thick coronal T2-weighted HASTE fs, axial T1-weighted FLASH fs,  3D MRCP SPACE, and MIP.

Two radiologists evaluated the three datasets for each patient in a random order to reduce recall bias. The following parameters were evaluated from the datasets: cyst and MPD size, cystic and MPD mural nodules, abrupt change in the MPD caliber, distal parenchymal atrophy, lymph node enlargement, and a solid pancreatic tumor presence. The WF and HRS analysis included cystic and MPD mural nodules, an MPD size of ≥ 5 mm, an abrupt change in the MPD caliber with distal pancreatic atrophy, a cyst of ≥ 3 cm, and/or lymphadenopathy.

Results showed agreement between longer protocols and USP for cystic mural nodules, MPD mural nodules, solid pancreatic tumor, and WF/HRS (94.9%, 99.1%, 99.1%, 92.4% respectively). Non-significant differences were reported in the largest cyst measurement nor in the mean MPD value.  In addition, no significant systematic bias in the difference between methods and the confidence intervals was observed.

Management and follow‐up of gallbladder polyps: updated joint guidelines between the ESGAR, EAES, EFISDS and ESGE

Kieran G. Foley1 · Max J. Lahaye2 · Ruedi F. Thoeni3 · Marek Soltes4 · Catherine Dewhurst5 · Sorin Traian Barbu6 · Yogesh K. Vashist7 · Søren Rafael Rafaelsen8 · Marianna Arvanitakis9 · Julie Perinel10 · Rebecca Wiles11 · Stuart Ashley Roberts12

European Radiology  volume 32, pages 3358–3368 (2022)

Incidental gallbladder polyps are a common sonographic finding, occurring in approximately 3–6% of the general population [1]. Although most are benign cholesterol polyps or inflammatory polyps, a small percentage of them are true neoplastic polyps. Despite gallbladder cancer being a relatively infrequent diagnosis [2], detection of malignancy at an early stage of disease is critical to improve survival rates because gallbladder cancer is associated with a poor prognosis [3].

The original guidelines for the management of gallbladder polyps were released in 2017. In this paper, the authors updated the European guidelines by incorporating new evidence regarding the management of gallbladder polyps into its recommendations. They made 8 recommendations that we will summarize. Recommendations 1 to 7 have changed from the previous guidance, whereas recommendation 8 is unchanged.

1. Primary investigation of polypoid lesions of the gallbladder should be with abdominal ultrasound. Routine use of other imaging modalities is not recommended presently, but further research is needed. In centers with appropriate expertise and resources, alternative imaging modalities (such as contrast-enhanced and endoscopic ultrasound) may be useful to aid decision-making in difficult cases.
Since the original guidelines, several studies have explored the potential of alternative modalities for detecting gallbladder polyps and differentiating dysplastic malignant from benign polyps. Although some techniques, like high-resolution ultrasound (HRUS), endoscopic ultrasound (EUS), contrast-enhanced ultrasound (CEUS), magnetic resonance imaging (MRI) and positron emission tomography (PET), tried to improve the detection of pre-malignant and malignant lesions, a size greater than 1 cm remained a factor independently associated with a neoplastic polyp [4; 5].

2. Cholecystectomy is recommended in patients with polypoid lesions of the gallbladder measuring 10 mm or more, providing the patient is fit for, and accepts, surgery. Multidisciplinary discussion may be employed to assess perceived individual risk of malignancy.
Several studies have investigated alternative size thresholds at which to intervene, but the overall quality of evidence remains low. In the absence of an alternative size threshold with better evidence, the group chose to leave the 10 mm threshold unchanged. Multidisciplinary team meetings were introduced in this update to discuss the best management of individual patients.

3. Cholecystectomy is suggested if no alternative cause for the patient’s symptoms is demonstrated and the patient is fit for, and accepts, surgery. The patient should be counseled about the benefit of cholecystectomy versus the risk of persistent symptoms. There was limited and low-quality evidence regarding the value of cholecystectomy, in patients with symptoms potentially attributable to the gallbladder.  One study reported that 61% symptomatic patients reported ongoing pain after their cholecystectomy [6].  So, in this update the group emphasized that symptomatic patients with gallbladder polyps should be counseled about the potential benefits of cholecystectomy versus the risks of persistent pain.

4.If the patient has a 6–9 mm polypoid lesion of the gallbladder and one or more risk factors for malignancy, cholecystectomy is recommended if the patient is fit for, and accepts, surgery.
These risk factors are:

• Age more than 60 years old;
• History of primary sclerosing cholangitis (PSC);
• Asian ethnicity;
• Sessile polypoid lesion (including focal gallbladder wall thickening > 4 mm).

A systematic review [7], which included 5,482 gallbladder polyps, identified the age threshold of more than 60 years as a significant risk factor for malignancy, resulting in the update of the age threshold (vs 50 years in the 2017 guidelines). In previous recommendations, only Indian ethnicity was considered a risk factor, however more recent reviews [8] suggested that the entire Asian population is at increased risk.

5. If the patient has either:

• No risk factors for malignancy and a gallbladder polypoid lesion of 6–9 mm
• Risk factors for malignancy and a gallbladder polypoid lesion 5 mm or less

Follow-up ultrasound of the gallbladder is recommended at 6 months, 1 year and 2 years. Follow-up should be discontinued after 2 years in the absence of growth.
The preview guidelines suggested that follow-up ultrasound is recommended at 6 months, 1 year and then yearly up to 5 years in these cases. In this update, the authors suggested that a limited strategy of one or two follow-up ultrasound investigations in the subsequent 1–2 years is sufficient to provide adequate reassurance for patients and clinicians, emphasizing that monitoring should be reserved for those who are potentially fit for surgery.

Imaging of Bowel Ischemia: An Update, From the AJR Special Series on Emergency Radiology

Michael C. Olson, Corrie R. Bach, Michael L. Wells, James C. Andrews, Ashish Khandelwal, Christopher L. Welle and Jeff L. Fidler

American Journal of Roentgenology: -. 10.2214/AJR.22.28140  https://www.ajronline.org/doi/abs/10.2214/AJR.22.28140

Intestinal ischemia represents an important pathological entity that still represent a challenging diagnosis for the Emergency Radiologist. This review article describes various common causes of mesenteric ischemia and provides to illustrate the multimodality imaging findings, especially CT that could be considered the first diagnostic tool in acute conditions.

After anatomical description of the mesenteric vasculature, the Authors considered the arterial thromboembolism, the mesenteric vein thrombosis and the nonocclusive mesenteric ischemia. The most common cause of acute mesenteric ischemia is represented by an arterial embolic disease that accounts for up to 50% of cases [1] and often results from underlying cardiovascular disease (e.g., atrial fibrillation or thrombi that form from a preceding myocardial infarction) [2]. The Authors specified that the superior mesenteric artery (SMA) is particularly susceptible to emboli due to its high flow rate and narrow branching angle from the aorta. Emboli often lodge 3-10 cm distal to the SMA origin, near the takeoff of the middle colic artery, which results in sparing of inferior pancreaticoduodenal branches and preservation of inflow to the proximal jejunum [3, 4]. A small proportion (approximately 15%) of emboli occur at the SMA orifice, which, in the absence of robust collateral circulation, may result in catastrophic small bowel ischemia. Thrombotic occlusion could be considered the second-most common cause of acute mesenteric ischemia, responsible for 20-30% of cases [5, 6]. The mesenteric venous thrombosis appears to be responsible of 5-20% of cases of acute mesenteric ischemia and is more frequently encountered in younger patient populations [2, 4]. Risk factors include, among others, some hypercoagulable states, such as those caused by Factor V Leiden mutation or deficiencies in proteins S, protein C, and antithrombin [22]. The superior mesenteric vein (SMV) and portal vein are commonly involved, and symptoms are more likely to develop in patients with thrombosis of peripheral mesenteric venous branches [5].

The review article also considers in a special section other entities such as the ileus, the strangulating bowel obstructions, the reperfusion findings as well as the colonic ischemia. Various imaging technique, from conventional radiograph to CT and CTA are considered, with special notes regarding the Dual Energy technique, protocols and advantages [7]. In conclusion, this review could provide a general critical approach to an important clinical question of mesenteric ischemia for the radiologist.

Distinction between ischemia (that could be a total reversible event) and infarction (irreversible, with death of the involvement intestinal segment) of the small and large intestines have been previously considered and described in literature [8,9]. The sequentiality of the ischemic damage and respective imaging findings (mainly CT) in different phases (from early ischemia to late infarction) and knowledge of the physiologic response of the intestinal wall to the vascular injury could be important to consider when scanning patients with suspected mesenteric ischemia. Whereas the “chronicity” of the ischemic event could be debatable to consider and distinguish, the acute findings related to bowel wall injury from impaired venous drainage or arterial etiology must be well known to avoid mistakes and delay in diagnosis.

Diagnostic performance of MRI for staging peritoneal metastases in patients with colorectal cancer after neoadjuvant chemotherapy

Rijsemus CJV, Kok NFM, Aalbers AGJ, Buffart TE, Fijneman RJA, Snaebjornsson P, Engbersen MP, Lambregts DMJ, Beets-Tan RGH, Lahaye MJ

Eur J Radiol. 2022 Apr;149:110225 doi: 10.1016/j.ejrad.2022.110225

Peritoneal metastases (PM) affect up to 30% of colorectal cancer (CRC) patients and remain the second leading cause of death after liver metastases (1,2).

The extent of PM is assessed by the peritoneal cancer index (PCI), which provides a measurement of the volume and extent of metastases. The PCI score combines the distribution of peritoneal implants at 13 abdominal and pelvic regions with the tumor size, being the most important and precise quantitative prognostic factor of peritoneal disease (3,4). Patients are eligible to undergo surgical cytoreduction (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) if PCI score is < 21, taking into account their location (5). Unfortunately, computed tomography (CT) underestimates the extent of PM and therefore it is not an accurate method to select patients who may benefit from CRS. With CT, small peritoneal nodules are often indistinguishable from the adjacent surrounding tissues, resulting in reduced sensitivity for peritoneal carcinomatosis (6).

Recent evidence has shown that abdominopelvic magnetic resonance imaging (MRI), including DW-MRI and gadolinium-enhanced MRI, significantly improves the staging and treatment in patients with PM from colorectal cancer (PM-CRC) due to its high accuracy in assessing PCI, compared to CT (7,8). While the diagnostic performance of DW-MRI to assess the PCI in patients with PM-CRC has been evaluated with good results, there are no studies that aimed to investigate PM-CRC after neoadjuvant chemotherapy (NACT).

This single center retrospective study was conducted at the Netherlands Cancer Institute in Amsterdam, a tertiary referral center for peritoneal surface oncology. The aim of this study was to evaluate diagnostic performance of DW-MRI in reassessing the PCI after NACT for patients with PM from colorectal cancer or appendiceal cancer who are potential candidates for CRS-HIPEC. The study included 47 patients from January 2016 until February 2021.

Two abdominal radiologists evaluated the PCI on restaging DW-MRI (mriPCI) and assessed the peritoneal lesions as suspicious if they were identifiable as solid or mucinous lesions on non-enhanced T2-weighted and gadolinium-enhanced T1-weighted images or as an area with diffusion restriction in DW-MRI imaging. The reference standard was PCI at surgery (sPCI). In all patients, sPCI was established by diagnostic laparoscopy, staging laparotomy or CRS-HIPEC. If CRS-HIPEC was performed, resected peritoneal lesions were evaluated and correlated with final pathological PCI (pPCI).

14 out of 47 patients were excluded because they had undergone surgery more than 42 days after the MRI scan; 33 out of 47 patients were eligible for inclusion. 19 out of 33 patients received 2 to 4 cycles of chemotherapy and 14 out of 33 received more than 4 cycles. Both readers correctly detected all 23 patients with resectable disease; however, the unresectable patients were not all correctly identified. The first reader detected 8 out of 10 unresectable patients (sensitivity 100% and specificity 80%) while the second reader identified 4 out of 10 unresectable patients (sensitivity 100% and specificity 40%).

The correlation between sPCI and mriPCI was 0.82 (0.66-0.91) for the reader 1 and 0.67 (0.43-0.82) for the reader 2. Six patients (26.1%) had pPCI of 0, indicating a complete regression of all resected lesions without any vital tumor remnants; five of these patients with complete response had a mriPCI of 3 or less.

Interestingly, this study corroborates in colorectal cancer the results of Jonsdottir et al. in which a group of patients with ovarian cancer underwent NACT before DW-MRI staging in the absence of significant differences between mriPCI and sPCI (7,9). This study shows that DW-MRI is an accurate diagnostic tool in determining the PCI after NACT because it could accurately select those patients in which a CRS-HIPEC was feasible; all patients with resectable disease were detected with MRI.

Incidence of pancreatic cancer during long‐term follow‐up in patients with incidental pancreatic cysts smaller than 2 cm

Masoud Nakhaei · Mathew Bligh · Victoria Chernyak · Abraham F. Bezuidenhout · Alexander Brook · Olga R. Brook

Eur Radiol 32, 3369–3376 (2022) doi: 10.1007/s00330-021-08428-1

Pancreatic cysts are frequent finding in patients undergoing cross-sectional imaging for non-pancreatic reasons, with prevalence ranging from 2.6% (on CT) to 20% (on MRI) [1], [2]. Most of these cysts reveal to be intraductal papillary mucinous neoplasms (IPMN), with low risk of malignant transformation [3]–[5]. Fukuoka guidelines suggest that small (less than 2 cm) cysts without high-risk stigmata, can be followed up with imaging [4], [5]. However, there is no consensus on how to follow up these cysts. The existing guidelines available on this topic propose different follow-up protocols, such as terminating follow-up after a time interval of dimensional stability or stopping follow-up only when the patient is no longer suitable for surgery[6]–[9]. The cause of this lack of consensus is to be referred to the fact that there is no definite data on the incidence of PDAC in patients with pancreatic cysts of these dimensions.

The objective of this study [10] is to evaluate long-term malignancy risk and mortality of small pancreatic cysts in asymptomatic patients with the purpose of optimizing follow-up protocols in this population.

In a retrospective multicenter study, 267 asymptomatic patients from Beth Israel Deaconess Medical Center (Boston, MA) with incidental MRI finding of pancreatic cysts, with diameter ranging from 5 to 20 mm, were enrolled in the “small pancreatic cyst” group. The selected patients had at least two abdominal MRIs at least six months apart. Patients with history of pancreatitis were excluded, as it is considered a risk factor for PDAC. 1459 patients from Montefiore Medical Center (Bronx, NY) with matching age decade, imaging modality (MRI vs. CT) and year of the index date formed the “no cyst” group. Patients with a diagnosis of any pancreatic neoplasm within 5 years before the date of the index study were excluded.

Endpoints of the study included mortality and incidence of pancreatic cancer; in case of pancreatic cancer occurrence, it was noted weather it developed in the same location of the cyst or from a different area.

In the “small pancreatic cyst” cohort, 0.7% of patients developed pancreatic cancer. 0.4% of patients developed low-grade dysplasia. Mortality was 21%, 4% of which was due to pancreatic cancer. In the “no pancreatic cyst” group, 1.2% of patients developed pancreatic cancer; mortality was 26%. The difference between the incidence of PDAC in the two groups did not appear to be statistically significant. During the radiological follow-up (mean 6.1 ± 4.2 years) the yearly growth rate was 0.0003± 1.8 mm/year or 0.7 ± 20.9%/year.

Interestingly, the most clinically relevant result of this study is that none of the PDAC diagnosed during the follow-up originated from the followed cysts.

The importance of this study resides in the fact that not only it evaluates the incidence of PDAC in patients with small pancreatic cysts but compares it with the incidence of PDAC in patients without cysts, proving that the presence of small cysts does not act as an additive risk factor in the general population.

These results are in line with a previously published paper from Chernyak and co-workers [11], where the incidence of PDAC less then 2 cm did not differ significantly from patients without cysts. On the other hand, larger cysts increase the risk by three times.

The retrospective design of the study may have caused some patient selection biases, the limited clinical data mentioned in the indication of the imaging study does not allow to completely rule out risk factors for PDAC, such as pancreatitis. Moreover, the enrolment of patients in the two groups was only based on the report, thus, patients with pancreatic cysts may have been either excluded from the “cyst group” or included in the “no cyst group”.

In conclusion, the results of this study show that the presence of small pancreatic cysts does not represent a risk factor for PDAC, since its incidence over a 6 years follow up period is similar in patients with less than 2 cm pancreatic cysts and patients without pancreatic cysts.

Branch-duct intraductal papillary mucinous neoplasm (IPMN): Are cyst volumetry and other novel imaging features able to improve malignancy prediction compared to well-established resection criteria?

Raffaella M. Pozzi Mucelli, Carlos Fernández Moro, Marco Del Chiaro, Roberto Valente, Lennart Blomqvist, Nikolaos Papanikolaou, Johannes-Matthias Löhr, Nikolaos Kartalis

Eur Radiol 32, 5144–5155 (2022). doi.org/10.1007/s00330-022-08650-5

Intraductal papillary mucinous neoplasms (IPMN) are epithelial pancreatic cystic tumours of mucin-producing cells that arise from the pancreatic ducts and are usually detected incidentally on cross-sectional imaging. IPMN can be divided into three types according to duct involvement: main duct, branch-duct, and mixed (affecting main and branch ducts) (1). Based on their degree of dysplasia, IPMN range from low-grade dysplasia (LGD) up to high-grade dysplasia and invasive carcinoma (HGD/INV) (1). Current guidelines base their management on several well-established resection criteria (3,4). The cyst size is associated with an increased risk of HGD/INV, but there is not a cut-off size risk established; thus, the size alone is an inappropriate parameter to perform surgery due to its poor predictive positive value for HGD/INV (2).

The aim of this retrospective single-center study was to assess the role of volume, morphology, and other well-established resection criteria in malignancy prediction of patients with branch-duct and mixed-type IPMN.

Patient selection was consecutively done from a prospectively collected database of 345 patients who underwent pancreatic surgery with histologically confirmed IPMN at Karolinska University Hospital from 2008 to 2019.

The inclusion criteria were: a) Preoperative pancreatic MRI with at least one axial and coronal T2W sequence and b) At least one histologically proven BD-IPMN detectable on the T2W images. The exclusion criteria were: a) Main-duct diameter ≥5 mm without a BD-IPMN clearly identifiable at preoperative MRI and b) Solid mass forming pancreatic cancer with or without a main pancreatic duct stricture.

The final study population was 106 patients.

The images of the pancreatic MRI closest to the date of surgery were evaluated by two experienced abdominal radiologists in consensus reading, and one cyst per patient was chosen for the analysis (the largest or the most suspicious for malignancy based on guidelines at the time of surgery). The collected imaging parameters were: maximum cyst diameter on T2WI (axial and coronal), elongation value (a relation between width and length) (5), cyst volume, main pancreatic duct diameter, contrast-enhancing mural nodules, cyst wall thickening (≥2 mm), progress in size during follow-up (≥5 mm/year), solitary/multiple lesions, and cyst location.

Multiple clinical parameters were collected from each patient's electronic record, including: age at surgery, gender, and serum levels of CA 19-9. Also, the grade of dysplasia from each resected IPMN was recorded.

Univariable logistic regression analysis was performed to identify variables associated with HGD/INV. Posteriorly, statistically significant variables were tested with multivariable logistic regression, adjusted for age and gender.

There were no statistically significant differences in cyst volume (OR=1.01, 95% CI: 0.99–1.02 p=0.12) or elongation value (OR=0.38, 95% CI: 0.02–5.93, p=0.49) between patients with LGD and HGD/INV. Also, there was not found an association between HGD/INV and maximum cyst diameter, wall thickness, solitary or multiple lesions, or progress in cyst size (≥5 mm/year). Histological cell subtypes did not correlate with cyst diameter, volume, or elongation value. The results showed that the only variables associated with HGD/INV were also ones that are present in current guidelines (2,3): the presence of contrast-enhancing mural nodules (OR=4.32, 95% CI: 1.18–15.76, p=0.02), the diameter of the main pancreatic duct ≥5 mm (OR=4.2, 95% CI: 1.34–13.1, p=0.01), and elevated serum levels of CA 19-9 (>37 µmol/l) (OR=6.72, 95% CI: 1.89–23.89, p=0.03).

Avoiding contrast-enhanced sequences does not compromise the precision of the simplified MaRIA for the assessment of non-penetrating Crohn's disease activity

Agnès Fernàndez-Clotet, Víctor Sapena, Nunzia Capozzi, Sonia Rodríguez, Maria-Carme Masamunt, Elena Ricart, Ingrid Ordás, Julian Panés, Jordi Rimola

Eur Radiol 2022 May;32(5):3334-3345; doi: 10.1007/s00330-021-08392-w. Epub 2022 Jan 15.

Magnetic resonance enterography (MRE) has gained a central role in the evaluation of small bowel in patients affected by Crohn’s disease; it is widely accepted as an imaging method with good ability to provide a detailed assessment of small bowel involvement [1]. MRE has been recently proposed as an alternative to ileocolonscopy, which could be often incomplete, and not able to describe transmural involvement and eventual presence of abdominal abscesses [2]. Moreover, MRE has a pivotal role in measuring therapeutic response, representing a noninvasive imaging tool to guide the clinicians in the decision-making process [3]. The use of contrast enhancement is a cornerstone in current MRE protocols, and it is also required for the Magnetic Resonance Index of Activity (MaRIA), one of the major MR grading systems to evaluate the response to therapy in Crohn’s disease [4]. However, MaRIA is a time consuming classification, and the recent evidence of gadolinium deposits in the brain concerns the clinicians, especially in young patients [5]. Then, to overcome these shortcomings and to make the score assessment easier, a novel simplified version of MaRIA (sMaRIA) has been proposed [6].

This study aimed to test the performance, in terms of accuracy, of sMARIA calculated with and without contrast-enhanced sequences, with the goal to assess the biologic therapeutic response in patients affected by Crohn’s disease. Authors prospectively enrolled 46 patients, selected according to the presence of endoscopic ulcerations in at least two intestinal segments, and eligible to be treated with biologic therapy. All patients underwent MRE and ileocolonoscopy within 1 month before starting therapy and they repeated the follow-up examinations (MRE and ileocolonoscopy) at 46 weeks. Ileocolonoscopy was considered the reference standard to assess disease activity by using Simple Endoscopic Score for Crohn’s Disease (SES-CD) [7]. The evaluation of inflammatory changes was conducted on five tracts of colon and terminal ileum. This approach was built to compare in a structured manner the MRE with ileocolonoscopy. Two abdominal radiologists, blinded to clinical and endoscopy results, classified the sMaRIA descriptors in the first round by using the unenhanced sequences (T2-sMaRIA) and in the second round, 1 month later, with all set of sequences (CE-sMaRIA). They calculated the agreement for both T2-sMaRIA and CE-sMaRIA to classify the biologic response in each intestinal tract and per-patient. In per-patient analysis, three different endpoints were evaluated for T2-sMaRIA and CE-sMaRIA: the MRE ability to identify patients with ulcer healing, MRE accuracy in decrease ≥50% of global scores, and MRE performance in identifying endoscopic remission. Overall, in identifying ulcer healing in per-patient analysis the agreement of T2-sMaRIA and CE-sMaRIA was comparable with ileocolonoscopy (sensibility = 80 and 76%; specificity = 95.2 and 95.2%; kappa = 0.74 [0.55-0.93] and 0.70 [0.5-0.9], respectively). Both T2-sMaRIA and CE-sMaRIA identified better the ulceration in the colon in comparison with the ileal segments (Cochran’s Q test <0.001 for both tests). Concerning the therapeutic assessment T2-sMaRIA and CE-sMaRIA were also like ileocolonoscopy for both treatment response (kappa = 0.44 [0.17 - 0.71] and 0.53 [0.28-0.79]) and remission (kappa = 0.43 [0.17-0.69] and 0.48 [0.22-0.73]). The standardized effect size was moderate for both CE-sMaRIA = 0.63 ([0.41-0.85] p < 0.001) and T2-sMaRIA = 0.58 ([0.36-0.80] p < 0.001) when was considered an improvement of at least 0.5 standard deviation in endoscopic evaluation (SES-CD), this cut-off was used as criterion for radiological changes.

Interobserver Variability in CT-based Morphologic Tumor Response Assessment of Colorectal Liver Metastases

Nina J. Wesdorp, Ruby Kemna, Karen Bolhuis, Jan H. T. M. van Waesberghe, Irene M. G. C. Nota, Femke Struik, Ikrame Oulad Abdennabi, Saffire S. K. S. Phoa, Susan van Dieren, Martinus J. van Amerongen, Thiery Chapelle, Cornelis H. C. Dejong, Marc R. W. Engelbrecht, Michael F. Gerhards, Dirk Grünhagen, Thomas M. van Gulik, John J. Hermans, Koert P. de Jong, Joost M. Klaase, Mike S. L. Liem, Krijn P. van Lienden, I. Quintus Molenaar, Gijs A. Patijn, Arjen M. Rijken, Theo M. Ruers, Cornelis Verhoef, Johannes H. W. de Wilt, Rutger-Jan Swijnenburg, Cornelis J. A. Punt, Joost Huiskens, Jaap Stoker, Geert Kazemier

Radiology: Imaging Cancer   https://doi.org/10.1148/rycan.210105

Colorectal cancer is one of the most common malignant neoplasms, ranking 2nd to 4th in terms of incidence globally (1). More than half of patients with colorectal cancer develop colorectal liver metastases (CRLM). Only 20% of these patients are eligible for curative therapy (resection and/or ablation). The remaining patients with CRLM most often receive systemic treatment to suppress the tumour load for secondary local treatment or in a palliative setting. The advent of targeted therapies such as bevacizumab and panitumumab has improved these patients’ outcomes.

Using size-based radiologic parameters, the RECIST 1.1 criteria are widely applied to evaluate tumour response to treatment. However, therapy induces not only size changes but also morphologic modifications.

This study evaluates interobserver variability in morphologic tumour response assessment according to set criteria in participants with CRLM treated with systemic therapy. The relation of morphologic tumour response with RAS/BRAF mutation status and targeted therapy, and the comparison of morphologic tumour response with the RECIST 1.1 measurements were secondary objectives.

The authors used a sample of 369 patients (from the CAIRO5 trial) with initially unresectable colorectal cancer with liver-only metastases. These patients were followed in one of the 54 medical centers included in the trial.

Exclusion criteria were: more than 15 CRLM at baseline or first follow-up CT examination, missing baseline or first follow-up CT, incomplete CT examination, technical error in diagnostic software and the use of MRI or PET with non–contrast-enhanced CT. This resulted in a sample of 156 patients. In addition, three other patients were excluded due to the presence of calcifications or the reduced size of lesions.

All the 153 patients in the final sample did a contrast-enhanced CT scan at baseline and at every two months during systemic therapy. Only the baseline and first follow-up CT scans in the portal venous phase were included in the current study.

Tumour response to systemic therapy was evaluated according to the morphologic criteria formulated by Chun et al (2). Morphology group 3 was characterized by heterogeneous attenuation and ill-defined tumour–liver interface, with or without peripheral rim enhancement. Morphology group 1 was described as homogeneous and low attenuation, with a sharply defined tumour–liver interface and an absence of peripheral rim enhancement. Morphology group 2 tumours could not be assigned to morphology group 1 or group 3 and were described as mixed attenuation, variable tumour–liver interface, and, if initially present, partially resolved rim enhancement. The morphologic response was defined as an optimal response if there was a change from either group 2 or 3 to group 1; a suboptimal response if there was a change from group 3 to 2; and no response if the morphology group did not change or moved to a higher group.

According to those criteria, three radiologists independently assessed tumour response on the baseline and first follow-up CT scans. Two additional radiologists evaluated disagreement cases. Interobserver agreement was calculated using Fleiss k.

Abbreviated non-enhanced magnetic resonance imaging in patients with acute necrotizing pancreatitis

Akash Bansal, Rajath Ramegowda, Pankaj Gupta, Jimil Shah, Jayanta Samanta, Harshal Mandavdhare, Vishal Sharma, Rakesh Kochhar, Manavjit Singh Sandhu

Abdominal Radiology (2022) doi: 10.1007/s00261-022-03531-3 

Acute pancreatitis is one of the commonest differentials of acute abdomen which presents to accident and emergency (1). It can be divided into interstitial oedematous pancreatitis and acute necrotizing pancreatitis (1). The Revised Atlanta Classification classifies pancreatic fluid collections according to the presence of necrosis and the interval from pain of onset (2).

CT is the commonest imaging modality used to determine the morphology of pancreatitis and its complications, however the use of MRI is inevitable in some cases. MRI is used in complicated cases as a supplement to CT, and in cases where CT is contra-indicated (such as contrast allergy or acute kidney injury) or when it is advisable to reduce radiation dose (such as in pregnancy or the need for multiple scans) (3). The patients requiring MRI are generally unwell and therefore the long acquisition time often leads to unreliable images of reduced quality.

Bansal et al carried out a retrospective study to assess an abbreviated MRI protocol based on a single axial T2 weighted sequence. They conducted a retrospective analysis of patients with acute necrotizing pancreatitis who underwent MRI between January 2017 and November 2020. Patients with moderately severe or severe acute pancreatitis who underwent MRI within two weeks of admission were included. The exclusion criteria were those with mild or chronic pancreatitis, and those whose MRI was performed later than 2 weeks following admission.

The complete MRI (cMRI) protocol included the following sequences: T2 weighted half Fournier acquisition single shot turbo spin echo (HASTE) axial and coronal, true fast imaging with steady state free precision axial and coronal, T1 weighted gradient echo axial sequence, coronal 2D and 3D MRCP sequences, and DWI with ADC maps. Contrast enhanced axial and coronal T1 weighted sequences using Magnevist were also acquired in some cases. For the abbreviated MRI (AMRI) protocol, only the T2 HASTE axial sequence was evaluated.

Two separate sets of data (AMRI and cMRI) were randomly presented to and independently analyzed by two radiologists who were blinded to the clinical details and to any previous imaging.

The following parameters were assessed: intrapancreatic and extrapancreatic necrosis, percentage of intrapancreatic necrosis (<30% or >30%), presence, site and size of collection, presence of wall, presence and percentage of solid components in the collection, venous thrombosis, presence of ascites, pleural effusion, gallstones, common bile duct stones, main pancreatic duct dilatation and disconnected pancreatic duct.

The growth pattern of liver metastases on MRI predicts early recurrence in patients with colorectal cancer: a multicenter study

Qian Cai, Yize Mao, Siqi Dai, Feng Gao, Qian Xiao, Wanming Hu, Tao Qin, Qiuxia Yang, Zhaozhou Li, Du Cai, Min-Er Zhong, Kefeng Ding, Xiao-Jian Wu, Rong Zhang

Eur Radiol, 2022 Apr 14. doi.org/10.1007/s00330-022-08774-8

The liver represents the main metastatic site of colorectal cancer: approximately 50% to 60% of patients with colorectal cancer develop liver metastases during the course of the disease (1). For patients with isolated liver metastases, locoregional treatments can be curative, as an alternative or in association with systemic chemotherapy: the complete resection of liver metastases can achieve up to 50% 5-year and 20% 10-year survival rates (2,3). Anyway, in up to 60% of patients with colorectal cancer liver metastases (CRCLM) the disease recurs early after treatment. The Authors’ aim was to test the feasibility of a qualitative assessment of hepatic lesions focused on the growth pattern of liver metastases on preoperative MRI, in order to find a useful and simple tool to estimate recurrency risk after surgery.

In this multicentric retrospective study 348 CRCLM patients with 820 metastatic lesions were enrolled from three different Chinese hospitals, between January 2012 and November 2020. All patients underwent a liver MRI within 1 month before surgery and follow-up CT/MRI examinations to monitor recurrence; no enrolled patient was diagnosed with extrahepatic metastases, or other simultaneous malignancies.

Two radiologists in consensus analyzed all contrast enhanced preoperative MRIs and categorized each liver metastasis into four growth patterns based on tumor shape, with reference to the gross classification of HCC (4): rough type, smooth type, focal extranodular protuberant (FEP) type and nodular confluent (NC) type.

The endpoints of the follow-up program included disease-free survival (DFS) and intrahepatic disease free survival (IDFS).

Patients with FEP- and NC-type metastases had shorter DFS and a higher intrahepatic recurrence rate than patients without such metastases in the liver (FEP type: median DFS 5.5 vs. 20.6 months, p = 0.044; 6-month intrahepatic recurrence rate 50.0% vs. 16.0%, p = 0.005; NC type: median DFS, 6.4 vs. 28.0 months, p = 0.007; 6-month intrahepatic recurrence rate, 35.7% vs. 18.6%, p = 0.023). Since no significant differences in DFS or IDFS were observed between patients with rough- and smooth-type metastases and those without such metastases in the liver (p > 0.05), FEP and NC types were classified as high-risk types, while rough and smooth types were classified as low-risk types. Subsequently, patients with high-risk-type liver metastases were renamed as high-risk patients, while patients only with low-risk-type liver metastases were renamed as low-risk patients. High-risk patients had shorter DFS and a higher intrahepatic recurrence rate than low-risk patients (median DFS: 6.4 vs. 28.0 months, p = 0.005; 6-month intrahepatic recurrence rate: 37.5% vs. 13.4%, p = 0.003).

Univariate and multivariate Cox regression analyses proved that high-risk-type liver metastases (hazard ratio [HR]: 2.319, 95% confidence interval [CI]: 1.442– 3.728; p = 0.011) and the number of liver metastases (HR: 1.793, 95% CI: 1.062–3.027; p = 0.029) were independent risk factors for DFS; moreover, high-risk-type liver metastases (HR: 2.169, 95% CI: 1.293–3.639; p = 0.003) were an independent risk factor for IDFS.

A small sample of 53 patients with 177 liver metastases accepted chemotherapy before surgery and had a liver MRI at baseline; in those patients, the Authors analyzed changes in the growth pattern of liver metastases after chemotherapy, and they observed that approximately 79.3% of low-risk types remained low-risk types, while 40.5% of high-risk types were converted to low-risk types. In addition, patients with high-risk types after chemotherapy had shorter DFS and a higher intrahepatic recurrence rate than those with low-risk types (median DFS: 5.9 vs. 33.1 months, p = 0.014; 6-month intrahepatic recurrence rate: 52.4% vs. 9.4%, p = 0.027).

A functional liver imaging score for preoperative prediction of liver failure after hepatocellular carcinoma resection

Ningbin Luo, Xiangyang Huang, Yinan Ji, Guanqiao Jin, Yunying Qin, Bangde Xiang, Danke Su, Weizhong Tang

European Radiology. 2022. DOI: 10.1007/s00330-022-08656-z

Monica Milazzo (radiology resident, University of Palermo, Palermo/IT) and
Roberto Cannella (radiologist and researcher, University of Palermo, Palermo/IT)

Hepatocellular carcinoma (HCC) accounts for about 75-85% of all primary liver cancers, representing one of the most important causes of cancer death worldwide [1]. Surgical resection is widely accepted as the most effective treatment option for HCC in patients with preserved liver function. Despite the improvements of post-hepatectomy mortality rates due to the advances in surgical technique and postoperative management, morbidity remains high. The post-hepatectomy liver failure (PHLF) is one of the most severe and challenging complications. It is related to the insufficient residual liver function and it represents a leading cause of hepatectomy-related mortality and increased cost of hospitalization [2, 3]. The incidence of PHLF ranges from 1,2% to 32% according to different definitions, characteristics of study population, and surgical procedures. Several predictors of PHLF have been explored in recent years with inconstant results to improve long-term survival in patients with HCC.

Bastati et al. [4] proposed and validated the functional liver imaging score (FLIS), a visual 6-point score, based on three imaging characteristics on gadoxetic acid-enhancement MRI: 1) liver parenchymal enhancement; 2) biliary contrast excretion; and 3) portal vein sign. The FLIS is calculated on the 20-minutes hepatobiliary phase after the administration of gadoxetic acid by summing semiquantitative assessment of each parameter, scored on an ordinal 0-2 scale. The FLIS reflects the residual hepatic function in patients with advanced chronic liver disease and it turned out to be an independent predictor for mortality in both patient with compensated and decompensated advanced chronic liver disease [5, 6].

A recent study by Luo and colleagues [7] assessed the potential of the FLIS to predict PHLF in patients with HCC in comparison with other routine liver functional parameters. This study included a large cohort of 502 patients (422 men and 80 women), who underwent hepatic resection and had a histologically confirmed HCC. In this cohort, the most common etiology of the chronic liver disease was hepatitis B virus in 425 (84.7%) patients. A total of 90 patients experienced PHLF and this was associated with a higher risk of 30-day and 90-day mortality (OR of 3.4 and 2.6, respectively). The gadoxetic acid-enhanced MRI exams were acquired within 1 month before surgery and they were assessed independently by two abdominal radiologists which assigned the FLIS to each patient.

The main study results demonstrate that PHLF was associated with cirrhosis, ascites, aspartate aminotransferase, platelet count, model for end-stage liver disease (MELD) score, albumin–bilirubin (ALBI) score, FLIS, and major hepatic resection. Interestingly, multivariate analyses revealed that only the FLIS and mayor hepatectomy were independently associated with the risk of PHLF. Particularly, a higher FLIS was associated with a lower risk of PHLF (OR 0.452) [7]. Importantly, the FLIS demonstrated a higher accuracy for the prediction of PHLF compared to other clinical scores including the MELD, ALBI score, and the indocyanine green 15-min retention rate. A FLIS lower than 4 predicted the PHFL with a sensitivity of 61% and a specificity of 79% [7].

The results of this study are relevant for the preoperative management of patients with HCC, as gadoxetic acid-enhanced MRI is often acquired for the preoperative HCC diagnosis and staging. In this setting, the assessment of FLIS on the hepatobiliary phase images can provide an additional functional information for the optimal selection of candidates to surgical resection. Moreover, the FLIS demonstrated an excellent reproducibility between different radiologists, and it may have the advantage to be easily assessed compared to other quantitative liver imaging functional parameters. Indeed, this visual assessment does not require complex equations or specific software for measurement of signal intensity. The main limitations of this retrospective study are the lack of comparison between different grades of PHLF and the low number of patients without viral hepatitis (14,5%), such as nonalcoholic fatty liver disease.

Added‑value of ancillary imaging features for differentiating hepatocellular carcinoma from intrahepatic mass‑forming cholangiocarcinoma on Gd‑BOPTA‑enhanced MRI in LI‑RADS M

Zheng W, Huang H, She D, Xiong M, Chen X, Lin X, Cao D

Abdom Radiol 2022 Mar;47:957-968. doi: 10.1007/s00261-021-03380-6

The Liver Imaging Reporting and Data System (1) is an imaging-based diagnostic system applicable in patients at high risk of hepatocellular carcinoma (HCC) (2). In LI-RADS, each liver observation is assigned a category that reflects probability of malignancy (2). LI-RADS M (LR-M) is a category for liver lesions that are definitely or probably malignant, but not specific for hepatocellular carcinoma (HCC) (1, 3). LR-M primarily aims to maintain the high specificity of LR-5 without sacrificing sensitivity to diagnose hepatic malignancies (1). HCC and intrahepatic mass-forming cholangiocarcinoma (IMCC) are the two predominant types in the LR-M group (4).

In this study, the authors aimed to identify reliable imaging features on Gd-BOPTA-enhanced MRI and determine the value of adding ancillary imaging features to distinguish HCC and IMCC in LR-M patients. Data were retrospectively collected from consecutive patients with pathologically proven HCC or IMCC. The inclusion criteria were as follows: a) pathologically proven HCC or IMCC by surgical resection or liver puncture; b) patients underwent Gd-BOPTA-enhanced MRI within three months before surgery or liver puncture; and c) patients were suitable for the LI-RADS categorization system according to the LI-RADS v2018 criteria. Among the remaining potentially eligible patients, only patients with liver lesions classified as LR-M were included, resulting in a final population of 116 patients with HCC (n= 82) and IMCC (n=34).

The LI-RADS imaging features were independently analyzed by two radiologists (with 11 and 5 years of experience in abdominal imaging). If the observations were classified to LR-M, the two readers would evaluate ancillary imaging features simultaneously.

Multivariable logistic regression analysis was performed to identify independent predictors to diagnose HCC among LR-M observations.

HCCs showed significantly more often an enhancing capsule (59.8%), while in IMCCs targetoid appearance on DWI (29.4%) and HBP (73.5%) were more common. Among the ancillary imaging features blood product in mass, fat in mass, mosaic architecture, round margin, intratumoral septa and small-scale central HBP hyperintensity were significantly more frequent in HCC. Peritumoral biliary dilatation and cloud-like enhancement on HBP were significantly more frequent in IMCC.

In the multivariable logistic regression analysis enhancing capsule, intratumoral septa and small-scale central HBP hyperintensity were identified as independent predictors for HCC over IMCC. The model where ancillary imaging features were added demonstrated a significantly superior AUC (0.918 vs. 0.845, p=0.021) and sensitivity (91.5% vs. 79.3%), but lower specificity (79.4% vs. 85.3%) compared to the model without ancillary imaging features for diagnosing HCC.

Diagnostic performance of ¹⁸F‑fluorodeoxyglucose‑PET/MRI versus MRI alone in the diagnosis of pelvic recurrence of rectal cancer

Verena Plodeck, Ivan Platzek, Johannes Streitzig, Heiner Nebelung, Sophia Blum, Jens‑Peter Kühn, Ralf‑Thorsten Hoffmann, Michael Laniado, Enrico Michler, Sebastian Hoberück, Klaus Zöphel, Jörg Kotzerke, Johannes Fritzmann, Jürgen Weitz, Christoph G. Radosa

Abdominal Radiology (2021) 46:5086–5094 https://doi.org/10.1007/s00261-021-03224-3

Colorectal cancer is the third most common cancer worldwide, and is expected that number will increase by around 60% to more than 2.2 million new cases by 2030. Rectal cancer accounts for about 40% of all cases of colorectal cancer (1,2).

Local recurrences rates have decreased significantly after the introduction of total mesorectal excision and neoadjuvant radiotherapy (3). In case of local recurrence, complete surgical resection is the only curative treatment, but due to the challenging method and the potential extent up to pelvic exenteration, accurate preoperative diagnosis is essential (4).

The diagnosis can be difficult, due to pelvic scarring and inflammatory/reactive changes after radiotherapy or anastomotic leaks (5,6). Follow-up of rectal cancer is usually done with CT, which is most commonly used, MRI and PET/CT. These methods have different sensitivities and specificities, with noticeable higher sensitivity in MRI versus CT, but comparable specificity. PET/CT was described to have a relatively low (58%) PPV for FDG-avid presacral lesions, but improved diagnostic performance after adding MRI sequences. A recent study demonstrated good accuracy of PET/MRI (7). The use of PET has been recommended in equivocal cases and prior to extensive resection (8).

The aim of this retrospective study was to compare ¹⁸F-FDG-PET/MRI and MRI in the diagnosis of pelvic recurrence of rectal cancer.

They included eligible forty-one PET/MRIs of forty patients, which were reviewed by four groups, in a blinded fashion, with a total of three radiologists and one nuclear medicine physician. To avoid bias, a time gap of 3 months was kept between the readings. Each finding was scored 0-4, depending on probability of recurrence.

MRI criteria for malignancy were:

• On T2: nodular or irregularly shaped soft tissue masses, inhomogeneous structure, signal intensities equivalent or higher compared to muscle and/or infiltration of adjacent organs.
• On DWI: high signal on b800 images with corresponding low signal on ADC maps.
• On CE MRI: inhomogeneous enhancement with suspicious morphology on T2.

PET/MRI criteria considered shape, location and intensity, by visual assessment, of ¹⁸F-FDG uptake. Therefore:

• Increased uptake compared to liver background was suspicious.
• Lower uptake than liver background in anatomical structures like ovaries or rectal stump, typical uptake in the urinary tract or along bowel loops was considered benign.
• Photopenic areas with slight uptake of the margins were considered fluid collections.
• Non focal uptake, less compared to background, was presumed to be due to inflammation, if this corresponded to MRI.

Lesions were considered malignant if they showed intense focal ¹⁸F-FDG uptake, as well as suspicious MR findings.

The results showed that PET/MRI leads to less equivocal findings and increases readers’ confidence in diagnosing or excluding local recurrence. Inter-reader agreement, sensitivity, specificity, PPV/NPV and accuracy are comparable for MRI and PET/MRI, with slightly higher values for PET/MRI. Also, PET/MRI showed higher AUC (0.97 versus 0.92), but not statistically significant.

Ablation Difficulty Score: Proposal of a new tool to predict success rate of percutaneous ablation for hepatocarcinoma

Conci S, D'Onofrio M, Bianco A, Campagnaro T, Martone E, De Bellis M, Longo C, Dedoni S, Vittoria D'Addetta M, Ciangherotti A, Pedrazzani C, Dalbeni A, Campagnola P, Mansueto G, Guglielmi A, Ruzzenente A.

Eur J Radiol. 2022 Jan;146:110097. doi: 10.1016/j.ejrad.2021.110097

Hepatocellular carcinoma (HCC) accounts for about 90% of primary liver cancer. Its incidence is increasing worldwide, representing the fourth most frequent cause of cancer-related death globally [1]. According to Barcelona Clinic Liver Cancer (BCLC) guidelines, local ablation is one of the curative treatment options available for HCC at the moment [2,3]. Success rates of local ablative techniques (LAT) range from 80% to 98,7% [4, 5, 6], regardless of the high rate of necrosis in the ablated area.

The authors of this study analyzed retrospectively the outcome of 585 nodules treated with radiofrequency ablation in 282 patients from 2010 to 2020, with the objective of developing an ablation difficulty score (ADS) to improve patient selection and treatment allocation. Ablation with microwave device, guided by CT-scan or fusion imaging or performed by laparotomy / laparoscopy were not included. Other exclusion criteria were the presence of macrovascular invasion and patients with follow up imaging not performed in their local radiology department.

Preoperative imaging, either CT or MRI, were used to measure the shortest distance between the edge of the nodule and the liver capsule, and to the major vascular structures. Nodules with distance ≤ 5 mm to vascular structures were defined perivascular, and those with distance ≤ 5 mm to liver surface sub-capsular.

A contrast-enhanced CT 30 days after the procedure was the imaging technique used to assess the ablation success. Incomplete ablation (IA) was defined as residual tumor on the edge of the ablated area. Failure ablation was considered after two consecutive procedures with IA. Ablation success was established as the absence of residual tumor after up to two consecutive procedures.

This study reported an ablation success rate of 85.5%. Univariate and multivariate analysis revealed that nodule’s size > 20 mm, isoechoic nodule appearance, sub-capsular location, perivascular location, and non-cirrhotic liver parenchyma were significantly related to failure ablation. Each one of these factors was awarded 1 point and the ADS was built up with a score from 0 to 5. Three categories of risk were established: low risk (ADS 0), intermediate risk (ADS 1), and high risk (ADS ≥ 2), with an ablation success rate of 93.5%, 85.8%, and 71.3% respectively. The cumulative local tumor progression (LTP) free survival rates at 1-year were 90.2%, 80.6%, and 72.3% for low, intermediate, and high-risk group, respectively. Only nodule size, isoechoic appearance, and perivascular location resulted to be independent factors for LTP free survival rates on univariate and multivariate analysis.

We believe that this study is relevant. On the one hand, LAT remains a widely used curative treatment for HCC thanks to its high success rate, feasibility and low postoperative morbidities [7,8]. On the other hand, the proposed ADS scoring system is a very simple and easy-to-use tool that provides additional and relevant information to guide HCC treatment decisions, reserving LAT in high-risk (ADS ≥2) nodules only for patients not suitable for surgery or liver transplantation.

The study had some limitations. Firstly, a potential risk of selection bias owing to the retrospective single-center design of this study. Secondly, only nodules treated with radiofrequency ablation were considered. Also, ablation with microwave devices or advanced local ablative techniques, such as ablation guided by fusion imaging, CT scan or CEUS, were not included in this study. The latter may explain the lower ablation success rate obtained for those nodules which location or imaging characteristics made it difficult to position the ablation needle.

Conventional-dose CT versus 2-mSv CT for right colonic diverticulitis as an alternate diagnosis of appendicitis: secondary analysis of large pragmatic randomized trial data

Hae Young Kim, Seungjae Lee, Dong Hwan Kim, Yousun Ko, Ji Hoon Park, Ara Ko, Seok Min Jeong, Sung Bin Park, Kyoung Ho Lee and for the LOCAT Group

American Journal of Radiology, November 2021. https://www.ajronline.org/doi/10.2214/AJR.21.25584

The adoption of lower dose CT in routine practice in young adults has been slow, partly due to concern regarding missing alternative diagnoses, such as right colonic diverticulitis (RCD), and other more subtle abnormalities.

The purpose of this paper was to retrospectively compare diagnostic performance of 2mSv low dose CT (LD-CT) to conventional dose CT (CD-CT) for the diagnosis of right sided diverticulitis in a relatively young cohort (ages 15-44) with suspected appendicitis.

The original randomized control trial was performed in Korea and involved 3074 patients with suspected appendicitis (1). These patients underwent random assignment for Low dose or conventional dose CT. The imaging findings were compared and it was concluded that the low dose CT was non-inferior for diagnosis of appendicitis. Of note, 37% of the original cases were positive for appendicitis.

This retrospective analysis reviewed all of the previously seen right colonic diverticulitis cases seen in the original trial. End points for the diagnosis of right colonic diverticulitis between the different scan dosage were statistically analysed with different end points. In addition, all of the previously seen right colonic diverticulitis cases were re-reviewed by 4 radiologists (2 consultants and 2 trainees). The radiologists were blinded to the cases with additional alternative pathology cases, totaling 200 LD-CT and 200 CD-CT cases. A proforma was used and review only commented on if right colonic diverticulitis was present, indeterminate or absent.

Results demonstrated that interobserver group differences were minute at 95% confidence intervals. Both Gwet and Kappa coefficients were used to assess interobserver differences. Gwet coeffient was preferable to Kappa in this cohort as the prevalence of diverticulitis was high and this statistic is less vulnerable to disease prevalence compared to other common statistics. Gwet coefficient (2) were high and comparable between the low dose and conventional dose groups.

The paper concluded that 2msv CT is comparable to conventional-dose CT for the diagnosis of right colonic diverticulitis.

There were a number of limitations with this paper which were highlighted by the authors. The patient demographic were Korean patients with a high prevalence of right sided diverticulitis, which is presumably related to diet (7% of the 3074 cases). Although less prevalent in western societies, this study and the randomized control trial still highlight that reduced CT dosage is accurate for alternative diagnoses to appendicitis in an acute setting.

Abbreviated MRI in patients with suspected acute appendicitis in emergency: a prospective study

Islam, G. M. N., Yadav, T., Khera, P. S., et al.

Abdominal Radiology (2021). doi:10.1007/s00261-021-03222-5

Acute appendicitis is one of the most common abdominal emergencies, with a lifetime risk of 7-8% (1). Nowadays, the requirement of appendectomy in patients without complicated appendicitis is being increasingly refuted, since in these selected cases the choice of antibiotic treatment-only avoids the risk postoperative morbidity. The most widely used imaging methods for the radiological diagnosis of acute appendicitis are transabdominal ultrasound (US) and computed tomography (CT).

US is more available than CT, but it has a lower accuracy: with US the visualization of the appendix is highly dependent on the skill of the sonographer, patient habitus, position of the appendix and presence of intestinal gas (sensitivity 44-100%, specificity 47-99%) (2-3).

Previous literature has demonstrated that magnetic resonance imaging (MRI) is superior to US in the diagnosis of appendicitis, and nearly equal to CT (4-5). The main limitations of MRI include its high cost, limited availability, and long examination times.

Therefore, the objective of this prospective study is to determine the feasibility and diagnostic performance of an abbreviated MRI protocol for the diagnosis of appendicitis.

A total of 152 consecutive patients with clinical suspicion of acute appendicitis were referred to the emergency department of radiology. The choice between surgical intervention and medical-only treatment was based on the specific institution’s protocol, based on a clinical-radiological assessment with ultrasound and CT in selected cases only. Of these 152 patients, 67 patients underwent MRI, based on the results of a severity score (Alvarado score ≥ 5) and were subsequently included in this study. The abbreviated MRI protocol was acquired on a 3T MR system (Discovery 750w, GE Healthcare) with patients in the supine position, with axial and coronal T2-Weighted (T2W) sequences and axial Diffusion-weighted Imaging (DWI). No oral or intravenous contrast agents or antiperistaltic agents were used in the study.

MRI images were analyzed by two radiologists, blinded to clinical and other imaging data, on consensus. Features analyzed were: maximum serosa-to-serosa diameter of the appendix, maximum wall thickness, T2 signal intensity in the wall and lumen, presence of diffusion restriction in the wall, fat stranding in the right lower fossa (RIF), presence of appendiculitis, free fluid in the abdomen, and presence of loco-regional mesenteric lymphadenopathy. For the diagnosis of appendicitis, an appendix greater than 6 mm in diameter with signs of inflammation was considered positive (6). T2 hyperintensity and diffusion restriction in the wall of the appendix were used to determine positivity in suspect cases.

Histopathological examinations (HPE) were used as reference standard in surgical cases (n= 39); in non-surgically treated cases, the clinical diagnosis at discharge and 3-months follow-up were used instead (n= 28).

The mean and median duration of acquisition with the abbreviated MRI protocol was 14 and 12.5 min, respectively. The appendix was visualized at MRI in 62/67 patients (92.5%) and a diagnosis of appendicitis obtained in 45/67. Of the remaining 22 cases, an alternative diagnosis was found in 6, and the remaining 16 were considered negative MRI examinations. Of the 39 patients who underwent surgery, HPE determined that 34 had appendicitis, 3 normal appendix, 1 cecal perforation, and 1 appendiceal diverticulum.

Assessment of morphological CT imaging features for the prediction of risk stratification, mutations, and prognosis of gastrointestinal stromal tumors

Roberto Cannella, Emanuele Tabone, Giorgia Porrello, Giovanni Cappello, Cecilia Gozzo, Lorena Incorvaia, Giovanni Grignani, Alessandra Merlini, Lorenzo D’Ambrosio, Giuseppe Badalamenti, Daniele Regge, Tommaso Vincenzo Bartolotta

Eur Radiol31, 8554–8564 (2021). https://doi.org/10.1007/s00330-021-07961-3

Dr. Charikleia Triantopoulou, Head of the Radiology Department and Anastasia Doukopoulou, Third-Year Radiology Resident ‘Konstantopouleion’ General Hospital of Nea Ionia, Athens, Greece.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Most commonly originate from the stomach (50-60%) and small bowel (30-35%) and occasionally are found in colorectum (5%) and esophagus (<1%). Nevertheless, they can arise anywhere along the gastrointestinal tract and rarely even in extra-gastrointestinal locations [1].

In order to achieve the appropriate treatment and patient’s management it is important to ensure an accurate preoperative risk stratification of gastrointestinal stromal tumors. The National Institutes of Health (NIH) consensus classification system is currently used to assess patient prognosis after surgical resection and is based on tumor location, size, mitotic count and rupture [2].

In this retrospective dual-institution study, the authors intended to assess the correlation between CT imaging features of GISTs with risk stratification, prediction of mutation status, and prognosis.

Eighty-eight patients with pathologically proven GISTs were included in the study. All of them had preoperative contrast-enhanced CT performed between 2008 and 2019, received no treatment before imaging and had available pathological analysis. All CT studies were reviewed by two readers with experience in abdominal imaging in a blinded fashion.

Firstly, they evaluated the location of the lesion, as well as the size and the growth (endophytic, exophytic or mixed). Also, the following morphological imaging features of GISTs were assessed: contour, margins, enhancement pattern, enhancement degree, presence of intralesional calcifications, intralesional hemorrhage, surface ulceration, cystic degeneration, tumor necrosis, intratumoral vessels, enlarged feeding vessels or draining veins and direct invasion of adjacent abdominal organs.

The analysis of CT studies revealed that the primary tumor was located in the stomach in 52 cases, and small bowel and colorectum in 32 and 4 cases, respectively. GISTs most commonly presented as large lesions measuring ≥ 5 cm with exophytic growth, well-defined margins, and variable amount of intralesional necrosis. Distant metastases were identified in 14 cases. According to NIH 2008 risk stratification criteria, 3 patients had very low-risk GISTs, 21 low-risk, 19 intermediate risk and 45 high-risk. Mutational analysis presented 50 KIT 11, 11 KIT 9, 14 PDFGRα mutations, and 13 wild-type GISTs.

After statistical analysis, it was shown that there are differences in imaging features according to the risk stratification of GISTs. The percentage of high-risk tumors demonstrating lobulated contour, heterogeneous enhancement, hypoenhancement on portal venous phase, presence of necrosis, severe intralesional necrosis, intratumoral vessels and enlarged feeding vessels was remarkably higher compared to low-to-intermediate risk GISTs. Independent predictors of high-risk GISTs were lesions size ≥ 5 cm and enlarged feeding vessels, whereas in the cases of GISTs without metastases, only lesions size ≥ 5 cm and lobulated contour independently predicting high-risk tumors.

Predictive value of gadoxetic acid-enhanced MRI for posthepatectomy liver failure: a systematic review

Qiang Wang, Anrong Wang, Ernesto Sparrelid, Jiaxing Zhang, Ying Zhao, Kuansheng Ma & Torkel B. Brismar

European Radiology (2021). doi: 10.1007/s00330-021-08297-8

Postpancreatectomy liver failure (PHLF) is a major complication after liver resection and is the leading cause of perioperative morbidity and mortality. The reported incidence is typically around 10%, depending on different PHLF criteria and individual medical centre experience, however a frequency of 43% has also been reported [1,2]. For this reason, there is an urgent need for effective and non-invasive biomarkers to predict and avoid PHLF.

Common investigations and scoring models for the evaluation of liver function include, blood biochemical tests, indocyanine green (ICG) retention test, the LiMAx ® test, Child-Pugh score and the Model for End-Stage Liver Disease (MELD). Whilst these provide information on global liver function, they do not take into consideration the heterogeneous distribution of liver function amongst the different liver segments, which is especially significant in liver fibrosis or cirrhosis patients or after chemotherapy [3].

Gadoxetic acid (Primovist ®) enhanced magnetic resonance imaging (MRI) is used as a routine preoperative workup for the detection of liver lesions and their characterisation. 50% of the contrast medium is taken up by organic anion-transporting polypeptides (OATPs) or sinusoidal membrane of normal hepatocytes, and is then excreted into biliary ducts [4]. Enhancement of liver parenchyma is determined by the equilibrium of this transport mechanism.

Wang et al. carried out a systematic review which aims to evaluate the efficacy of gadoxetic acid-enhanced MRI-derived parameters as an imaging biomarker in preoperative prediction of PHLF. Studies evaluating the incidence of PHLF in patients who underwent preoperative liver function assessment using gadoxetic acid-enhanced MRI were included in a systematic literature search. The Quality In Prognostic Studies (QUIPS) tool was adopted to evaluate the risk of bias. Out of a total of 114 studies found in the systematic research search, 15 studies were considered eligible.

Most studies included were marked as low to moderate risk of bias in each domain of QUIPS. The most commonly used parameter was relative liver enhancement or its related parameters. The reported incidence of PHLF ranged from 3.9 to 40%, and the predictive sensitivity and specificity of gadoxetic acid-enhanced MRI parameters varied from 75 to 100% and from 54 to 93% in ten reported studies. A majority of the studies revealed that the gadoxetic acid-enhanced MRI parameter was a predictor for PHLF.

Risk factors for PHLF may result from patient aspects (namely age, body mass index, chronic diseases), liver quality (cirrhosis, hepatitis, neo-adjuvant chemotherapy), and factors related to the surgery itself (such as intraoperative blood loss, time of in-flow occlusion) [5].

CT angiography of abdomen and pelvis in critically ill COVID-19 patients: imaging findings and correlation with CT chest score

Harsna V. Vadvala, Alam Shan, Elliot K. Fishman, Rakhee S. Gawande

Abdominal Radiology. Published online, 11 June 2021. https://doi.org/10.1007/s00261-021-03164-y

Dr. Charikleia Triantopoulou, Head of the Radiology Department and Paraskevi Vlachou, Consultant Radiologist ‘Konstantopouleion’ General Hospital of Nea Ionia, Athens Greece.

The COVID-19 disease is a global pandemic, affecting more than 185 countries worldwide. SARS-COV2 is a highly infectious virus, responsible not only for acute respiratory syndrome, but also encompasses a high possibility for vascular and coagulation disorders, the leading factor for high mortality rates.

COVID-19 disease seems to result in a multi system dysfunction (1) with the involvement of several organs as well as vascular involvement. Endothelial injury and inflammation associated with SARS-COV2, mediate reactions which promote vascular complications.

In this retrospective study, the authors intended to focus on the most common vascular abnormalities seen in COVID-19 patients and combine them with the severity of lung disease.

COVID-19 patients admitted to the hospital underwent CTA chest, abdomen and pelvis or CTA abdomen and pelvis studies. Patients should be >18 years old, with diagnosis of COVID-19 infection. Exclusion criteria for this study were examinations performed prior to diagnosis, or examinations performed later than 3 months from initial COVID diagnosis. All studies were reviewed by two independent experienced radiologists.

Firstly, CT chest score was estimated. The five lung lobes were evaluated individually, on a scale from 0 (no involvement- 1 for <5% involvement, 2 for 5-25%, 3 for 26-50%, 4 for 51-75%) to 5 (for more than 75% involvement). The sum of the scores of all five lobes ranges from 0 to 25 (maximal involvement).

Then, analysis of CTA abdomen and pelvis revealed many vascular disorders. Most common were hematomas (46,7%). Second comes active vascular extravasation (24.4%). 8 patients had vascular occlusion and finally artery occlusion was seen in 3 patients. Arterial pseudoaneurysm was even rarer.

After statistical analysis, it was proven that there is strong association between high incidence of vascular disorders and higher CT chest score. Patients with moderate (11-17) to severe (18-25) scores, had had 6,22 to 21 times more possibilities to develop vascular disorders, compared to those with low CT chest score (2).

Additionally, high CT chest score seems to be associated with other types of injury (non-vascular), as abdomen and pelvis CT reveals. Most common sites of involvement are biliary tree, liver, kidneys and GI tract.

In this study, the authors try to summarize all vascular complications in a very helpful and comprehensive way. They also refer to other studies, i.e. Nadkarni et al (3), which emphasizes the benefits of prophylactic anticoagulation therapy, in comparison to those who did not receive any anticoagulation. A total of 46,7% developed a hematoma and 24,4% of patients had emergency active vascular extravasation.

The split scar sign as an indicator of sustained complete response after neoadjuvant therapy in rectal cancer

Inês Santiago, Maria Barata, Nuno Figueiredo, Oriol Parés, Vanessa Henriques, António Galzerano, Carlos Carvalho, Celso Matos, Richard J. Heald.

Eur Radiology 2020 Jan;30(1):224-238.  doi: 10.1007/s00330-019-06348-9

Total mesorectal excision (TME) is nowadays a standard surgery for rectal cancer, that showed significant increase in 5-year survival and decrease in local recurrence.[1]
Moreover, clinical trials and guidelines support the use of neoadjuvant radiation for further oncologic improvement in high-risk patients.[2] It was shown that up to 15–27% of patients who underwent preoperative chemoradiation had no residual viable tumor cells detected in the resected specimen.[3,4]
The studies demonstrated similar outcomes in those patients who later underwent surgery and those who were managed with “watch and wait protocol”, avoiding significant morbidity and mortality risks associated with TME in a second group.[5]
Watchful waiting is now an established policy in many colorectal centers worldwide.  This strategy requires close surveillance protocols for early detection of regrowth, including both imaging studies and colonoscopy. MRI is playing a fundamental role in assessing rectal wall and mesorectum before, during and after treatment. During the last decade, MRI response assessment is mainly based on tumor regression grade, evaluating intermediate residual tumor signal and low fibrosis signal on T2 weighted imaging6, and diffusion weighted imaging, that improves accuracy, but still depends on reader’s experience and quality of the image.

Inês Santiago and co-authors reported a new radiologic pattern of sustained complete response, that they called “split scar sign” (mrSSS), evaluated on high resolution T2-weighted images, and measured its diagnostic performance. This new pattern, according to the authors, is easy to assess and has a high specificity and PPV.

This is a retrospective study that enrolls fifty-eight patients who underwent neoadjuvant therapy for rectal adenocarcinoma in their institution between 1/10/2012 and 1/3/2017.
Patients’ demographics and clinical data was collected by physician uninvolved in imaging reading. Rectal MRI images were blindly and independently analyzed by two gastrointestinal radiologists, with 12 and 10 years of experience, respectively. Observers performed initial rectal cancer staging and later analyzed post neoadjuvant pelvic MR, acquired with a mean interval of 9.1 weeks after the end of radiotherapy.

On the first round: the presence of the split scar sign (mrSSS+) -a radiologic sign observed on T2-WI and characterized by a particular morphologic pattern of the tumor scar- was considered indicative of a sustained clinical response (SCR). It is characterized by the presence of an inner, markedly T2-hypointense, regular layer of tissue at tumor location, corresponding to the fibrosed submucosa, covered by normal mucosa, or denuded when ulceration is present; and a homogeneous intermediate signal intensity layer underneath it, corresponding to a markedly thickened and partially fibrotic muscularis propria. At the periphery, a T2-hypointense layer of variable regularity and thickness is usually apparent, translating perirectal fibrosis. It may, however, be absent, particularly in early-staged tumors. In mucinous tumors or tumors which respond with mucinous degeneration, the intermediate signal intensity may be replaced with high signal intensity, corresponding to mucin pooling. Vessels may pierce the outer hypointense layer in positive cases. On the other hand, the split scar sign is considered absent (mr SSS-) when the inner or the outer hypointense layer (when present) are bulged or breached by intermediate signal intensity, either the scar is completely hypointense or heterogeneous, with a “disorganized” appearance.

On a second round the authors assessed the relative proportion of intermediate signal intensity on T2-WI (mrT2), and of high signal intensity on high b-value diffusion-weighted imaging (mrDWI), separately and without taking into consideration morphologic pattern of the scar.

Endoscopy was performed upon patient restaging and tumor p stage was retrieved from the pathology reports in operated patients.
The reference standard was SCR, defined as pathologic complete response or long-term local recurrence-free clinical follow-up (minimum follow-up period of 1 year).

Qui-square test was employed in search for associations between SCR and mrSSS, mrT2, mrDWI and endoscopy. Interobserver agreement for imaging parameters was estimated using Cohen’s kappa (k).

The obtained results were the following: mrSSS was significantly associated with SCR, with specificity= 0.97/0.97, sensitivity= 0.52/0.64, PPV= 0.93/0.94, NPV= 0.73/0.78, and AuROC= 0.78/0.83 for observers 1/2, respectively. According to their results, the authors divided all patients in two main groups: mr SSS+ patients have a 97% chance of achieving a SCR, and those with mr SSS- have a 73–78% chance of failing to do so.

Postoperative complications of colorectal cancer

Pallan A, Dedelaite M, Mirajkar N, Newman P.A, Plowright J, Ashraf S

Clinical Radiology. July 2021. DOI: doi.org/10.1016/j.crad.2021.06.002

Colorectal cancer (CRC) imaging, both pre and post op, has become a more common and complex imaging finding. Sound radiological and surgical knowledge is required to promptly detect and aid manage of post-surgical complications as colorectal surgery is associated with high morbidity of 35%, and mortality of 1-16.4% [1].

This educational review article, in the first part illustrates in a detailed yet diagrammatic style, the type of colorectal surgeries. The second part of the review, focuses on the post-operative complications which are logically described with their incidence together with which imaging techniques are best suited to identify these complications.

Surgeries are described in detail and include traditional surgeries like segmental resection, Hartmann’s procedure, anterior resection, abdominoperineal resection and new minimal invasive procedure’s such as trans-anal endoscopic microsurgery (TEMS) and trans-anal minimally invasive surgery (TAMIS). The descriptions and illustrations including the anatomy are easy to understand and will help guide the radiologist; particularly of note was a systematic explanation of different type of anterior resection depending on the level tumour. Those who may not have done a surgical rotation in the past would benefit from these.

Second part of the review focuses on complications; firstly focusing on anastomosis leak (AL) as a common complication with a rate of 1-19 % [2]. Interestingly the paper divided the leaks into three clinical grades A to C as this effects clinical management [8], and the review also categorised these in terms of onset after surgery. Lower rectal anastomoses are associated with higher leak rates [ 3,4]. CT with intravenous contrast medium (CECT) and endoluminal contrast medium is the preferred imaging modality in diagnosing AL and is superior to water-soluble contrast medium enema (WSCE) [4]. Tabulation of the imaging protocol provided for use on left and right sided anastomosis was given. There was a good description of radiological findings with appropriate illustration; these were further separated by what to expect given the number of post-operative days. The pitfalls of using WSCE was described.

Multiple modalities can be used to characterise fistula along with associated findings. Although the review describes fluoroscopic fistulography as excellent in visualising the tract, it is limited in use of extra luminal findings. The review compares use of CECT with both oral and direct luminal contrast with MRI. MRI was suggested to be useful for diagnosing chronic fistulation.

Associated collections, anatomical distortion or inflammatory change are seen with both CT and MRI. It was suggested luminal distension when using MRI with water-based soluble solution can aid diagnosis. These practices however vary depending on local protocol and individuals.

Post-operative strictures are common with incidence of between 3-30% [5]. The review clearly identified risk factors that would help the radiologist plan studies; with ischemia, previous anastomotic leak and radiotherapy quoted as risk factors. Although they can be identified on either WSCE, CT colography or water enema CT examinations, the radiological features are universal as described in the review as short, smooth narrowing with normal mural thickness and no extra luminal mass. There are very useful illustration in multiple modalities in the review.

Although a rare complication (0.5-4.9%), post-operative bleeding can be serious [6,7]. The paper gives a detail illustration on use of multiphasic CECT with high flow rate to aid diagnosis of active bleeding. There is an adequate explanation on the type of vascular injury to be expected depending on the type of surgery that has been performed as well as pointers to make note previous history of radiotherapy. This provides a good illustration on where to look out for the bleed. Interestingly left sided colonic resection was noted to be associated with an iatrogenic injury of the spleen at rate of 1.1% and right hemi-colectomies associated with a 1.6% incidence of injury of the superior mesenteric vein.

Imaging of abdominal complications of COVID-19 infection

Caruso D, Zerunian M, Pucciarelli F, Lucertini E, Bracci B, Polidori T, Guido G, Polici M, Rucci C, Iannicelli E, Laghi A.

BJR Open. 2021 Jul 5;2(1):20200052. doi:10.1259/bjro.20200052

The severe acute respiratory syndrome Coronavirus 2 (Sars-CoV-2) is typically characterized by respiratory symptoms. However, during the pandemic, other abdominal organs seem to be involved in the disease due to systemic effects of the SARS-CoV-2.
Currently, it is world-wide accepted that in some cases COVID-19 infection can present primarily with abdominal symptoms such as abdominal pain, diarrhea.
Abdominal symptoms seem to be related to angiotensin converting enzyme 2 (ACE) expression in the gastrointestinal and biliary tract. Briefly, COVID-19 may affect various abdominal organs, and cause typical and less typical abdominal imaging findings. Caruso et al. reported in their review article the imaging of abdominal complications related to COVID-19 infection [1].

1. Small and large bowel - high expression of ACE2 receptors on enterocytes membrane. CECT (contrast-enhanced CT) is the imaging modality of choice and shows gastrointestinal complications in up to 49% of the cases [2,4]:
- typical bowel wall thickening, submucosal oedema, bowel dilatation, pericolic fluid and fat stranding; bowel ischemia due to mesenteric and portal vein thrombosis
- atypical CECT findings include pneumatosis intestinalis, appendicitis

2. Liver - direct cytopathic virus effect; up to 62% of the COVID-19 patients have elevated ALS, AST and GGT enzymes, with hepatic steatosis, but no typical imaging features have been reported [5].

3. Kidneys - expression of ACE2 receptors on podocytes and proximal convoluted tubules cells and also direct virus-induced cytopathic effect; up to 19% of COVID-19 patients develop acute renal dysfunction; no typical imaging findings were reported [6].

4. Pancreas - SARS-CoV-2 was isolated from a pancreatic pseudocyst, but the pathogenesis is not totally clear yet. Up to 16% of the patients have pancreatic involvement, with acute pancreatitis associated with COVID-19 as the main finding [7].

5. Gallbladder - expression of ACE2 receptors in the biliary system. Imaging shows typical acute cholecystitis findings: gallbladder distension, wall thickening, with mural/mucosal hyperenhancement, fluid and fat stranding [8].

6. Spleen - involvement is related to the prothrombotic effect of COVID-19. Splenic infarction with typical CECT findings was reported: peripheral, wedge-shaped hypo enhancing area [9,10].

In conclusion, abdominal involvement of COVID-19 is related in many cases to the ACE2 receptors expression, and it is not such a rare event. It is crucial that radiologists keep in mind a possible abdominal finding of COVID-19 patients. The above-mentioned paper provides an overview of all COVID-19-related abdominal complications and should be kept in mind by members-in-training as well as senior doctors.

Multiparametric US for Identifying Patients with High-Risk NASH: A Derivation and Validation Study

Sugimoto K, Lee DH, Lee JY, Yu SJ, Moriyasu F, Sakamaki K, et al.

Radiology 2021; 000: 1-10. https://doi.org/10.1148/radiol.2021210046

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of the metabolic syndrome and is defined as the presence of 5% or greater hepatic steatosis in the absence of competing liver disease etiologies, use of drugs causing steatosis or other chronic liver diseases (1).
It encompasses a spectrum of clinical conditions, from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH). Patients with NASH have a higher risk of developing fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). NAFLD is becoming a concerning health problem worldwide and the most common cause of liver disease globally (2).

Liver biopsy is the gold standard for the diagnosis of NASH. Its histological defining features are hepatic steatosis, hepatocellular damage (ballooning degeneration), inflammation, and fibrosis (3). Two previous studies observed that NAFLD with stage 2 or higher fibrosis and liver injury have a particularly high risk to develop complications (cirrhosis and HCC). They identified these patients as having high-risk NASH and proposed them as candidates for pharmacological treatment with anti-inflammatory and anti-fibrotic agents (4,5).

In this study, the authors aimed to identify patients with high-risk NASH using noninvasive methods. This was a retrospective cross-sectional study that analyzed data collected between April 2017 and March 2019 in Japanese patients with NAFLD. Findings were validated in an independent Korean dataset. Patients with suspected NAFLD were included and were evaluated with ultrasonography (US), liver biopsy, and clinical tests. Ultrasonography was performed immediately before liver biopsy, after 6 hours of fasting. The authors chose three US markers to estimate the degree of liver steatosis, fibrosis, and inflammation: liver stiffness (LS), attenuation coefficient (AC), and dispersion slope (DS), respectively. Liver biopsy was performed in all patients to be used as a reference standard, and NASH was defined as the presence of steatosis, hepatocyte ballooning, and lobular inflammation. Each patient underwent standard clinical evaluation with biochemical testing including aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels, and AST-ALT ratio.

Three multivariate regression models for high-risk NASH were built. Model 1 comprised US-based markers (LS, AC, and DS, defined as the LAD-NASH score), Model 2 serum-based markers, and Model 3 US-based and serum-based markers. Model 1 showed the second-highest area under the receiver operating characteristics (AUC) for detection of high-risk NASH, at 0.86 in the derivation study sample and 0.88 in the validation study sample. A dual cut-off approach was used to assess the diagnostic performance of Model 1 in the detection of high-risk NASH in the training cohort. With a cut-off for sensitivity greater than 90%, positive predictive value (PPV) was 69% and negative predictive value (NPV) was 87.5%. With a cut-off for specificity greater than 90%, they were 86.5% and 71.4%, respectively.

The LAD-NASH score resulted useful in both groups to identify patients with high-risk NASH, with a positive predictive value (PPV) of 86.5% and a negative predictive value (NPV) of 87.5% for respectively ruling in and ruling out patients with high-risk NASH among the population of patients with NAFLD. Having been configured to have two thresholds, a rule-in and a rule-out cut-off, the score can be used either as a screening tool or as a diagnostic test.

MRI radiomics features of mesorectal fat can predict response to neoadjuvant chemoradiation therapy and tumor recurrence in patients with locally advanced rectal cancer

Jayaprakasam VS, Paroder V, Gibbs P, Bajwa R, Gangai N, Sosa RE, Petkovska I, Golia Pernicka JS, Fuqua JL 3rd, Bates DDB, Weiser MR, Cercek A, Gollub MJ.

Eur Radiol. 2021 Jul 29. doi: 10.1007/s00330-021-08144-w. Epub ahead of print.

Colorectal cancer is the third most common cancer worldwide and the second cause of oncologic-related mortality. Rectal cancer accounts for ~30% of the total cases of colorectal malignancies (1). The standard-of-care treatment for patients with locally advanced rectal cancer (LARC) is neoadjuvant chemotherapy (nCRT) followed by total mesorectal excision (TME) (2). However, the individual response is very heterogeneous, ranging from a pathological complete response to no tumor regression or even disease progression (3). Recently, radiomics has gained increasing interest, more and more papers investigating the efficacy of radiomics features as biomarkers for lesion characterization and tumor prognosis, including for rectal cancer (4,5).

In this new study by Jaypar and colleagues, the focus is on the radiomics features extracted not from the rectal tumor, but from the mesorectal fat. The authors aimed to assess the potential role of radiomics analysis of mesorectal fat for the prediction of clinical outcomes of LARC.

This retrospective study included 236 patients with LARC who underwent total nCRT and TME. The following clinical outcomes were evaluated: pathologic complete response (pCR), local and distant recurrence, clinical (cT) and post-treatment (ypT) T categories, clinical (cN) and post-treatment (ypN) N categories, and clinical (cTNM) and post-treatment (ypTNM) TNM stages. Most patients had a cT category <4 (n=201), cN category>0 (n=213), post-treatment ypT category >0 (n=190), were post-treatment node-negative patients (n=176) and without local or distant recurrence (n=164, n=171 respectively). 101 radiomics features were extracted from the unfiltered, T2-weighted axial images of the baseline rectal MRI scans. Mesorectal fat segmentation was performed individually by three radiologists, excluding other structures such as tumor deposits, lymph nodes and extramural vascular invasion. Only features with a good intraclass coefficient (ICC>0.6) were included for further analysis (81 features).

Mann-Whitney test was firstly employed to select the significantly different radiomics parameters among each clinical outcome. Afterwards, using support vector machine algorithms and 5-fold cross validation, the authors developed different predictive models for each outcome. ROC curve analysis was conducted and area under the curve (AUC), sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated to evaluate the performance of each model. The best performing model was the one for distinguishing between pCR and non-responders (AUC=0.89, Se=78.0%, Sp=85.1%). Also, radiomics models significantly distinguished patients with local and distant recurrence from those with no recurrences (AUC=0.79 and 0.87, respectively). The resulting AUCs for discriminating between patients with cT4 category/those with <cT4 category and between post-treatment node-negative patients/node-positive patients were 0.80 and 0.74 respectively. The radiomics model for predicting the post-treatment ypT category achieved an AUC=0.86. However, the radiomics features did not differ significantly between cN<0 and cN>0 patients or between cTNM stage 2 and stage 3 patients, therefore no models were built for these outcomes.

The novelty of this research consists of shifting the focus of radiomics analysis from the tumour itself to the peritumoral environment in predicting cancer outcome. This issue has been investigated in several malignancies such as breast or lung cancer (6,7). However, only one recent study by Shaish et al included features obtained from the peritumoral region in the development of predictive models for assessing tumor response and prognosis of rectal cancer (8). Similar with the current study, their research has reported promising results, achieving an AUC=0.80 for predicting pCR using only features derived from mesorectal compartment.

Evaluation of the mesorectal fat may offer valuable prognostic information since the growth and dissemination of rectal cancer is closely related with the changes of the nearby adipocytes. Recent papers have showed that metabolic alterations in cancer-associated adipocytes can lead to secretion of various growth factors and remodeling factors that can interfere with cancer development and even therapeutic response (9,10). Therefore, assessment of peritumoral fatty environment may represent a new area of research, not only for rectal cancer but also for other types of abdominal/gastrointestinal tumors.

CT abnormalities of the pancreas associated with the subsequent diagnosis of clinical stage I Pancreatic Ductal Adenocarcinoma more than one year later: a case-control study

Toshima F, Watanabe R, Inoue D, Yoneda N, Yamamoto T, Sasahira N, Sasaki T, Matsuyama M, Minehiro K, Tateishi U, Gabata T.

AJR Am J Roentgenol. 2021 Jun 23. doi: 10.2214/AJR.21.26014.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive pancreatic cancer with very poor prognosis. PDAC accounts for about 90% of primary pancreatic cancers and the 5-year overall survival is reported to be lower than 5% [1]. Surgical resection with complete tumor eradication (R0 margins) is the only curative option for patients with PDAC. However, most of patients are not candidate to surgical resection as the PDAC presents with locally advanced disease and extensive vascular infiltration, or metastatic disease. Early diagnosis of PDAC can improve the prognosis but it is often challenging in clinical practice as small lesions are commonly isodense to the background nontumoral pancreatic parenchyma on contrast-enhanced Computed Tomography (CT). Early PDAC may lack of clinical symptoms and tumor markers are not routinely adopted as screening test. The only imaging manifestations of early-stage PDAC could be the presence of secondary findings such as pancreatic ductal dilatation, glandular atrophy, and abrupt main pancreatic duct cut-off [2-4].

A recent retrospective study published by Toshima et al. [5] investigated the early findings of PDAC observed on the pre-diagnostic CT acquired at least one year before the clinical diagnosis. The authors performed a case-control study with a study group including patients with stage I PDAC who had a pre-diagnostic CT acquired at least one year before the diagnostic CT for PDAC, and a matched control group of patients without PDAC who underwent CT examination at least 10 years before the diagnostic exams [5]. Imaging analysis was performed by two radiologists who reviewed the most recent pre-diagnostic CTs in the PDAC and control groups, reporting six main focal pancreatic abnormalities: pancreatic mass, focal main pancreatic duct dilatation, focal pancreatic atrophy, focal faint parenchymal enhancement, cyst, and calcifications [5].

A total number of 103 patients with PDAC and 103 controls were included in this study [5]. When comparing the most recent pre-diagnostic CTs, patients with PDAC showed more frequently focal pancreatic abnormalities than the control group (53% vs 23%). Particularly, patients with PDAC had more commonly focal main pancreatic duct changes (13.6%), focal pancreatic atrophy (37.6%), and focal faint enhancement (26.2%) compared to controls without PDAC. A pancreatic mass was retrospectively identified in only 5% of cases on the pre-diagnostic CT in patients who developed PDAC. Interestingly, the site of focal abnormality on the pre-diagnostic CT corresponded to the site of PDAC in the diagnostic CT in 98% of patients. After the review of all pre-diagnostic CTs, focal pancreatic abnormalities were observed with higher frequencies on pre-diagnostic studies acquired 1-2 years before the PDAC diagnosis (65%), while no abnormality was observed in studies acquired with an interval time greater than 10 years before the diagnosis. Moreover, the authors observed that patients who developed PDAC demonstrated more frequently progression of these abnormalities over time compared to controls (10% vs 0%).

This study provides important information for the evaluation of focal pancreatic abnormalities that can predate the diagnosis of stage I PDAC [5]. The recognition of these focal findings could allow the early diagnosis of PDAC and improve the overall prognosis of those patients. It is important to note that the site of these findings corresponded to the site of PDAC diagnosis in 98% of cases. Moreover, temporal changes of focal abnormalities were exclusively observed in patients who developed PDAC. Therefore, a strict follow-up or further imaging assessment with MRI or endoscopic ultrasound should be considered in presence of these focal pancreatic abnormalities.

The frequency of focal abnormalities reported in this study was lower compared to some prior investigations including pre-diagnostic CTs with different interval time [6, 7]. This could be explained by the inclusion on only CTs acquired with an interval time greater than one year before the PDAC diagnosis in the study by Toshima et al. [5], while a higher frequency on pancreatic abnormalities is more likely to be observed in other studies that performed imaging closer to the clinical diagnosis [6]. Moreover, histopathological samples of these focal abnormalities has not been obtained at the time of pre-diagnostic CT due to this retrospective study design [5]. The pathophysiological changes of these abnormalities remains debated as they can be related to early tumoral changes or underlying non-tumoral conditions that can predispose to PDAC development [5].

Radiomics of hepatocellular carcinoma

Sara Lewis, Stefanie Hectors, Bachir Taouli

Springer Science+Business Media, LLC, part of Springer Nature 2020

Radiomics is defined as the quantitative extraction, analysis and modeling of a large amount features from medical images (mostly CT and MRI images, but also US and PET), in relation to prediction targets, such as clinical end-points, and pathological and genomic features.

Hepatocellular carcinoma (HCC), the third leading cause of cancer-related death in the US and the fourth worldwide, is a heterogeneous and therapy-resistant disease. The HCC characterization at the individual patient level is urgently needed [1, 2, 3].

The aim of the authors is to promote the use of radiomics in clinical practice in order to obtain, using non-invasive methods, information about the tumor, reflective of HCC heterogeneity and aggressiveness, to stratify patients to a personalized therapy.

Several studies have demonstrated the validity of radiomics in the recognition of many HCC features: from histopathological characterization to the prediction of response to therapy, from the risk of recurrence to the prediction of patient’s outcome; all this succeeding in overcoming the limits of invasiveness and of small sample size of liver biopsy.

Among the main characteristics of HCC detected by radiomics, has been proposed the presence of microvascular invasion (MVI, defined by the invasion of tumor cells into a vascular space lined by endothelium), for which specific features have been elaborated: the “radiogenomic venous invasion” (RVI) score and the “two-trait predictor of venous invasion” (TTPVI). The role of radiomics in the detection of MVI is crucial, as the MVI has been reported as the strongest independent predictor of early tumor recurrence and poor prognosis [4, 5, 6].

Genetic and immune phenotypes also contribute to define the prognosis of patient affected by HCC: several studies have shown the validity of radiomics in the detection of these tumor features. In particular, a study involving 39 patients has proven the possibility, starting from qualitative CT and MRI imaging data, of demonstrating a significative association of these phenotypes with gene signatures of aggressive HCC phenotype, with odds ratios (OR) ranging from 4.44 to 12.73 (p < 0.045) [7, 8, 9].

Radiomics plays a role throughout all the diagnostic and therapeutic process of HCC, as it can be used to predict the tumor’s response to therapy. Kim et al. have demonstrated the superiority of a combined model in which are associated pre-treatment radiomics features and clinical factors of the patients (HR 19.88; p < 0.0001) in predicting patient survival, compared to either the clinical or imaging data alone [10].

Finally, outcome has been investigated in patients after surgical and non-surgical therapies. In particular, recurrence of disease after surgery is a frequent occurrence (from 31,6 to 40% of patients), depending on whether they perform a liver transplant or a partial resection, respectively [11, 12]. In addition, a pre-operative MRI imaging study involving 100 patients has identified the radiomics feature most predictive of ER after partial resection, regardless of the HCC size: the entropy, the manifestation of tumor heterogeneity [11, 12, 13].

Nowadays there is an increasing evidence that encourages the implementation of radiomics in all stages of the diagnostic and therapeutic process of HCC; although its use is currently limited by several factors, such as the need for dedicated softwares and trainings, which result in additional costs, and the lack of standardization in the various stages of radiomics studies.
In conclusion, a greater diffusion of radiomics in clinical practice could translate into a concrete benefit for the patients in terms of outcome, and its use could be considered also as an instrument for early diagnosis.

A comparative study of the pancreas in paediatric patients with cystic fibrosis and healthy children using two‑dimensional shear wave elastography

Ferhat Can Piskin, Sibel Yavuz, Sevgul Kose, Cagla Cagli, Dilek Dogruel, Gokhan Tumgor, Kairgeldy Aikimbaev

J Ultrasound 2020 Dec;23(4):535-542. doi: 10.1007/s40477-020-00432-3. Epub 2020 Feb 7.

Cystic fibrosis (CF) is a monogenic disease [1] with an incidence of 1/2500 live births, characterised by an autosomal recessive inheritance caused by mutations in the CFTR gene on chromosome 7. The deficiency of the cystic fibrosis transmembrane regulator (CFTR) protein leads to clinical manifestations of CF [2]. This protein is expressed on the surface of membrane of secretory and absorptive epithelial cells of several organs like pancreas, liver, intestine, airway and sweat gland [3]. In particular, pancreatic insufficiency affects about the 85% of the CF patients and results in the malabsorption of fat and protein [4]. In CF disease the progressive loss of acinar tissue caused by enzyme autodigestion of pancreas parenchyma starts in the intrauterine life and leads to inflammation and fibrosis [5, 6]. Ultrasound is a methodical frequently used in patients with CF due to absence of radiation exposure and due to large access to the methodical. Has been described in literature that CF patients frequently have ultrasonographic alteration in pancreatic parenchyma  [7]. In particular, the severely affected pancreas appears hyperechoic and small, as expression of pancreatic atrophy and replacement of the pancreatic parenchyma by fibrous tissue and fat [8]. However, the majority of studies in literature only describe qualitative ultrasounds pancreatic characteristics of CF patients.

The aim of the authors of the present study is to compare quantitative sonographic values obtained with shear wave elastography (SWE) on paediatric patients with already diagnosed cystic fibrosis, with healthy paediatric cohort. They conducted their study on 38 CF and 38 healthy children who underwent a first evaluation through conventional B-mode and a second 2D-SWE evaluation. Some parenchymal characteristics of pancreas such as echogenicity (compared to the liver echogenicity), homogeneity, stiffness, size of the head, body and tail and capsule sharpness were evaluated during B-mode evaluation. During the 2D-SWE evaluation 2D elastography colour maps were obtained and circular ROIs of 5x5 mm were placed in, during a single breath-hold. This was repeated five time separately for the head, body and tail. Then, mean values were recorded. For the CF group, on the conventional US evaluation the mean diameters of the head, body, and tail of the pancreas were significantly higher in the health children group than in the CF group (p = 0.016, p < 0.005, and p < 0.005, respectively). The mean 2D-SWE values of the patients with CF were 1.01 ± 0.16 m/s for the head, 1.03 ± 0.05 m/s for the body, and 1.02 ± 0.05 m/s for the tail, while those of the healthy control group were 1.31 ± 0.01 m/s for the head, 1.28 ± 0.08 m/s for the body, and 1.30 ± 0.10 m/s for the tail. On 2D-SWE evaluation, pancreatic values of the CF group were significantly lower than those of the healthy control group (all p < 0.005 for the pancreatic head, body, and tail, respectively). Using ROC values the threshold value for the head, body, and tail of the pancreas were determined as 1.19, 1.13, and 1.12 m/s respectively and the sensitivity of the test was determined as 81.5%, 76.3%, and 73.3%, while the specificity was 97.3%, 100%, and 100%, respectively.

The study carried out and the results obtained could be very relevant in the CF scenario because literature lacks quantitative information about pancreatic status in the evolution of CF in children. Engjom T. et al. assessed some qualitative pancreatic parenchymal characteristics in patient with CF > 15 years old, such as hyper-echogenicity and lipomatosis, which are related to the exocrine insufficiency. Nevertheless they only performed a qualitative evaluation, based on a visual analogue scale (VAS), with an acceptable inter-observer variability [9].

Portal phase alone is equivalent to multiphasic phase for CT diagnosis of acute non-traumatic pains in an emergency context

Herpe G, Boucebci S, Cassan T, Verdier M, Simonet C, Sztark G, Tasu JP

Emerg Radiol. 2020 Apr;27(2):151-156

Acute non-traumatic abdominal emergencies (ANTAE) represent one of the most frequent causes of access in the ED (1), embracing life-threatening conditions and self-limiting ones. Due to the comparable clinical findings and lack of sensibility and specificity of laboratory tests, ANTAE is a medical challenge for emergency physicians. For this reason, imaging is often required for definitive diagnosis and treatment (2).

Although ultrasonography is the first-choice non-invasive imaging modality, multidetector computed tomography (MDCT) has shown stronger accuracy in reaching the correct diagnosis (3). Multiphasic scanning protocol – which includes the acquisition in pre-contrast, arterial, portal venous, and delayed phases of contrast enhancement – is usually the most common approach (3), even though many recent publications (2, 4, 5) have demonstrated that in specific clinical non-traumatic abdominal settings the correct diagnosis can be reached with the same accuracy cutting off unnecessary phases and thus significantly lowering radiation exposure.

Herpe G. and coworkers emphasize the importance of lowering radiation exposure assessing that portal-phase only (PVP) acquisition protocol is equivalent to a multiphasic one, in term of radiological diagnosis concordance of ANTAE in the ED. The authors performed a retrospective study including 250 patients admitted to the ED for suspected ANTAE, including at least a pre-contrast phase, late arterial phase (LAP) and portal phase (PVP). Cases of suspected active hemorrhage and known malignancies were secondarily excluded since the multiphasic protocol is here recommended (6). 196 CT studies were examined. The multiphasic protocol (pre-contrast phase ± LAP + PVP) and the PVP alone were reviewed independently by nine radiologists who determined the most appropriate diagnosis with five-point confidence scale. Diagnosis concordance and radiation were compared by chi-square test: PVP-alone diagnosis was concordant with the multiphasic protocol without difference in term of confidence reading (kappa coefficient between the two diagnosis 98,5% (CI 95%= 95.6–99.7, p < 0.001), with a 61% decrease of radiation dose.

Results are consistent with other previous publications, confirming the inter-observer agreement between multiphasic and simplified acquisition protocol in abdomino-pelvic CT in the ED (2, 4, 5, 7), suggesting that in this scenario limiting radiation exposure does not have an impact on the management of patients.

However, to the best of our knowledge, there are no guidelines on how to standardize CT protocol in ANTAE since the most appropriate protocol relies upon clinical presentation (8). For this reason, when it is not possible to exclude malignancies and/or active bleeding from the initial clinical evaluation, multiphasic protocol should remain the gold standard (6). The most clinically relevant limit of this approach remains misinterpretation of spontaneously hyper-dense structures (i.e. biliary tract stones), difficult to detect and characterized with the only PVP phase. Nevertheless, some authors have suggested that additional scan might be taken with minimal doses (9, 10) just to obtain the additional necessary information limiting radiation exposure and without compromising the diagnostic accuracy of the exam.

In conclusion, considering the limitations of the study (e.g., retrospective design, low number of patients, lack of data about diagnostic accuracy) it is important to bear in mind the importance of using adequate protocols in the ED avoiding unnecessary ionizing radiation exposure, as many patients admitted in the ED suffer from acute self-limiting benign diseases.

Quantification of liver fat content in liver and primary liver lesions using triple-echo-gradient-echo MRI

Nougaret S, Monsonis B, Molinari N, Riviere B, Piron L, Kassam Z, Cassinotto C, Guiu B

Eur Radiol. 2020 Sep;30(9):4752-4761. doi: 10.1007/s00330-020-06757-1. Epub 2020 Apr 22. PMID: 32318848

Incidence of focal liver lesions (FLL) detection parallels growth in imaging utilization. Hemangiomas, focal nodular hyperplasias (FNH), and adenomas (HCA) are the most commonly solid benign lesions that arise in noncirrhotic liver. Metastases are the most common malignant lesions in noncirrhotic livers. Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) occur in the setting of chronic liver disease. Despite FLL usually having typical imaging characteristics, differential diagnosis by visual assessment only can be difficult sometimes or it requires contrast media administration mandatorily.
However, quantitative MRI imaging is an emerging research field that is increasingly assuming an important role in the characterization of FLL with unenhanced MRI protocol.

Authors, with their study, aim to quantify and compare whole liver parenchymal and intralesional fat fraction in primary liver lesions, such as HCC, HCA and FNH, using a triple-echo-gradient-echo-sequence.
Chemical shift MRI techniques are a non-invasive method for fat quantification within a specified volume [1, 2]. Routinely dual-echo in-phase (IP)/out of phase (OP) imaging is used for subjective evaluation of intralesional fat in liver lesions. However, the dual-echo technique is hampered by T1 and T2* relaxation times which may underestimate fat fraction when T2* is short (for example in the setting of iron-containing lesions) [3]. A triple-echo technique has been developed, which consists of a breath-hold, triple-echo spoiled gradient-echo sequence with consecutive first IP, OP, and second IP echo times. This method enables the quantification of fat fraction, corrected for T2* decay and minimizing T1-related effects (by decreasing the flip angle at 20°) [4-6].

It is a retrospective study that included 128 consecutive patients that underwent a liver MRI for lesion characterization. For each patient, a triple-echo sequence was performed before contrast medium injection on 1.5T scanner for fat evaluation. Then, the obtained images were post-processed and analyzed quantitatively and qualitatively by a radiologist. Quantitative analysis was performed by a Radiologist, with 3 years of experience in gastrointestinal imaging, by drawing regions of interest (ROIs) around the liver lesion on each slice of the fat fraction map, referring to the other sequences to delineate the whole tumor volume. Care was taken to avoid contamination of these ROIs by the normal liver parenchyma. Further, a large ROI representing the “normal” liver parenchyma was drawn for each patient. The same radiologist performed a qualitative analysis of fat quantification by visual evaluating the decrease in signal intensity on OP/IP images.

Among the 128 included patients, there were 47 HCCs, 25 HCA, and 56 cases of FNH suspected on MRI. Forty-nine patients had histologic confirmation of the diagnosis following ultrasound-guided biopsy. Where biopsy was not performed (27 patients in the HCC group (57%), 47 patients in the FNH group (84%), and 5 in the HCA group (20%)), lesion characterization was made on MRI in conjunction with clinical history, follow-up MRI, and laboratory results.

Results confirmed that this technique is accurate to quantify fat fraction in a tumor volume. According with pathologic findings, results demonstrated the relatively higher intralesional fat content of HCC and HCA compared to FNH. Furthermore, the previously published 5.56% threshold to assess liver steatosis might not be applicable in analysis of a solitary liver lesion when used to distinguish between fat-containing and non-fat-containing lesions because was solely used to determine liver steatosis. Authors, in their cohort, found that a lower cutoff of 2.7% was able to accurately diagnose FNH over HCA.

Clinical relevance of gallbladder polyps; is cholecystectomy always necessary?

Madelon J.H. Metman, Pim B. Olthof, Johannes B.C. van der Wal, Thomas M. van Gulik, Daphne Roos & Jan Willem T. Dekker

International Hepato-Pancreato-Biliary Association

DOI: https://doi.org/10.1016/j.hpb.2019.08.006

Gallbladder polyps are lesions of the gallbladder wall that protrude into the gallbladder lumen. They are commonly seen at ultrasound of the abdomen with a prevalence of 0.3 to 9.5%^3,5. After cholecystectomy, polyps are observed in 0.004 to 13.8% of specimens³.

The differential diagnosis for a gallbladder polyp is wide and includes pseudotumours, in addition to benign and malignant tumours. Pseudotumours include cholesterol polyps, focal adenomyomatosis and inflammatory lesions that can be caused by infection². Sludge is another potential mimic of a polyp. The literature estimates 30% of polyps are adenomatous polyps of the gallbladder, which have potential for malignant transformation. Patients with gallbladder carcinoma have a poor five-year survival rate of less than 5% due to a hidden and rapid progression of spread, which makes most disease unresectable at diagnosis⁴. Cholecystectomy is favoured for patients who are deemed to have malignant potential of a gallbladder polyp.

Most gallbladder polyp guidelines advocate for cholecystectomy if the polyp size at ultrasound is larger than or equal to 10 mm, or if the size has increased beyond a threshold during ultrasound surveillance².

This study looks at the correlation between ultrasound and histopathological findings after cholecystectomy for suspected gallbladder polyps. A retrospective analysis was performed at two Dutch institutions for all cholecystectomies performed between January 2010 and August 2017, with a total of 3547 operations. Of these 110 were performed for suspected gallbladder polyps. 2 patients were excluded due to a known diagnosis of primary sclerosing cholangitis, which is known to increase malignant potential of polyps. Most patients (60%) had multiple polyps; median diameter 10 mm. 54 patients underwent ultrasound surveillance with an increase in growth of their polyps prompting cholecystectomy.

Surprisingly, most pathological specimens (65%) did not identify any macroscopic abnormality. Polyp-like lesions were observed in 22 (20%) of the specimens. The remaining specimens showed cholesterolosis and irregular foci of the gallbladder wall. Three pyloric gland adenomas were identified. The remaining specimens showed benign entities. None of the pyrloric gland adenomas had features of dysplasia or malignant transformation.

Out of the 108 operations, adverse events were recorded for 3 patients and classified as Dindo IIIa (complications requiring surgical, endoscopic or radiological intervention) or higher. The adverse events were sepsis secondary to bile leak, re-admission for percutaneous drainage of a biloma and surgery for an incarcerated trocar hernia.

This study reflects similar findings observed in the literature, which is that most gallbladder specimens following surgery for suspected gallbladder polyps predominantly showed pseudopolyps with no malignant potential. Pyloric gland adenomas have an unknown risk of malignant transformation. In a separate study of 165 polyps with pyloric subtype there were 44 showing high grade dysplasia and 2 showing adenocarcinoma¹. In this same study 48 had no abnormality and 51 had cholesterolosis.

LI-RADS v2018 major criteria: Do hepatocellular carcinomas in non-alcoholic steatohepatitis differ from those in virus-induced chronic liver disease on MRI?

Barat M, Nguyen TTL, Hollande C, Coty JB, Hoeffel C, Terris B, Dohan A, Mallet V, Pol S, Soyer P.

Eur J Radiol. 2021 May; 138:109651.

DOI: 10.1016/j.ejrad.2021.109651. PMID: 33740627

Currently, the diagnosis of hepatocellular carcinoma (HCC) is based on cross-sectional imaging, namely contrast-enhanced computed tomography (CECT) and magnetic resonance imaging (MRI), setting the primary endpoint in the identification of the tumor in the early stage, when patient's condition and liver function can lead to surgical treatment. The main risk factors for developing HCC are virus- and alcohol-induced cirrhosis (1). Patients with nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH), especially in the Western countries, also have a mild risk for developing HCC (2). Contrast-enhanced CT and MR imaging features of HCC, i.e. enhancement during the arterial phase and wash-out in the portal-venous phase, are worldwide accepted and endorsed by the LI-RADS (3). However, LI-RADS can't be applied to NASH patients, which have a twofold increased risk of HCC-related mortality (4).

In this setting the Authors of the present paper have retrospectively validated MRI LI-RADS major features in patients affected by NASH, enrolling a total of 82 patients (41 HCC with virus-induced cirrhosis and 41 with NASH) from two centers. The final diagnosis was obtained according to the histopathological results. All patients underwent liver MRI examination on a 1.5T scanner before and after intravenous administration of a gadolinium-based extracellular contrast agent (gadoterate meglumine and gadobenate dimeglumine in 32 and 9 patients with NASH and in 33 and 8 patients with virus-induced cirrhosis, respectively). MRI examinations of the two groups were compared for imaging presentation, LI-RADS major criteria, and LI-RADS categorization (5) by two independent readers, blinded to clinical and histopathological data.

Authors reported no statistically significant differences regarding tumor longest diameter (30.3 ± 20.9 in NASH vs 38.0 ± 26.3 mm in virus group, respectively, p=0.121), signal drop on IP/OP T1W imaging (11.8 ± 18.5 vs 6.0 ± 9.7%, p=0.464) and ADC value (975 ± 257 vs 1048 ± 253 ×10^-3 mm²/s, p=0.197). Moreover, no significant differences were found regarding qualitative variables, in particular location (right liver lobe 76 vs 63%, p=0.337), arterial phase hyperenhancement (93 vs 98%, p=0.616), wash-out (63 vs 83%, p=0.502), tumor capsule (68 vs 61%, p=0.488), and portal vein invasion (12 vs 24%, p=0.253), with an overall good agreement for all features, except for tumor capsule in NASH patients (k=0.367).

In both groups, the most represented LI-RADS category was 5 (63 vs 80%), followed by 4 (22 vs 12%) and 3 (15 vs 7%), with no significant difference between groups (p=0.303) and a good agreement between the two readers (k=0.802 for NASH patients and k=0.720 for virus-induced cirrhotic patients).

Two important previous studies published in literature examined the importance of imaging features of HCC in NASH patients: Alsharan et al. (6) and Thompson et al. (7) reported the non-rim like hyperenhancement during the arterial phase in the majority of patients (100% and 93%, respectively).  Same results were reported by the three groups regarding tumor capsule, observed in 63% of patients enrolled by the present study, 60% by Alsharan et al., and 71% by Thompson et al. However, similar results were not reported for the wash-out appearance on the portal-venous phase, observed in 40% and 21% (lsharan et al., and Thompson et al) respectively).

Adrenal metastases: early biphasic contrast-enhanced CT findings with emphasis on differentiation from lipid-poor adrenal adenomas

F. Zhu, X. Zhu, H. Shi, C. Liu, Z. Xu, M. Shao, F. Tian J. Wang

Clinical Radiology 76 (2021) 294-301

Dr Rajiv B. Karia (Consultant GI/HPB and Interventional Radiologist, Chesterfield Royal Hospital & Nottingham University Hospitals, UK)

The adrenal gland is a site of both primary and metastatic malignant tumours as well as the most commonly identified benign tumour, adrenal adenomas. With a significant increase in use of CT for patients with previously known malignancies as well as for non-oncology patients, there has been an increase in number of incidentally identified adrenal tumours.

Adrenal metastasis (AM) and adrenal adenomas (AA), are the most common malignant and benign tumours[1]. Although on un-enhanced CT, attenuation of less that 10HU would be highly suggestive of an AA [1], approximately 30% of AAs are lipid poor[2] having a HU above 10[3] and hence un-enhanced CT are unable to reliably differentiate the two on un-enhanced CT.

Further imaging usually requires a chemical shift MRI or a delayed contrast-enhanced CT identifying relative washout of the lesion[4]. This retrospective study was used to identify imaging features to help differentiate AMs from AA, using un-enhanced CT and early biphasic contrast-enhanced CTs. This study identified 123 patients mostly based on histological diagnosis either at surgery or biopsy. However it also identified a few cases from follow-up imaging based on rapid increase in size (more than double within 6 months suggestive of AMs). One can be confident of the end point differential between AM and AA from this. All patients had unenhanced CTs, and biphasic arterial and portal venous CTs.

The study reviewed multiple imaging parameters; size: longest diameter (LD), shortest diameter (SD) and its ratio (LD/SD ratio); CT attenuation: unenhanced phase (CTu), arterial phase (CTa) and venous phase (CTv); degree of enhancement: degree of enhancement in arterial phase (DEAP), portal venous phase (DEPP); peak enhancement ratio PE/U (where PE was the highest value between DEAP and DEEP and U was the CTu). Further parameters such has absolute percentage washout (APW), and relative percentage washout (RPW) were also calculated.

This paper clearly identifies the presence of necrosis, location (unilateral/bilateral) and shape as significant differences between the two lesions. However, one can see the limitations of identifying necrosis particularly within smaller lesions, as it is at times difficult to differentiate necrosis from foci of low attenuation due to small quantities of microscopic fat component. This is not an issue with large lesions which are prone to cystic necrosis [5]. Although bilateral lesions maybe more commonly associated adrenal metastasis, we have all seen bilateral lipid poor AA, diagnosed on MRI. I think the qualitative assessment tools identified within this paper may not provide the reporter with the confidence to call AM over AA.

This paper has gone into great depth illustrating the quantitative analysis performed at identifying statistically significant radiological characteristics. The study identified as CTu, DEAP, DEPP, DEpeak and PE/U as all parameters providing statistically significance in differentiating AM from AA. However for a reporter to benefit from this, these findings need to simple to identify, a logical part of the reporting process and intuitive to use.

Univariate and ROC analysis showed PE/U ratio (<1.25), CTu (>32.2 HU), DEpeak (<43.15 HU), DEPP (<37.65 HU), presence of intralesional necrosis, location (bilateral adrenal), and irregular shape were independent factors for distinguishing AMs from AAs. However interestingly and more important for a reporter, when at least four of the criteria were combined, a sensitivity of 88% and specificity of 93% was achieved. I think with such high specificity using these parameters may prevent patients undergoing unnecessarily delayed ‘washout’ phase CTs or further assessment with time consuming MRIs.

Observer agreement for small bowel ultrasound in Crohn’s disease: results from the METRIC trial

Gauraang Bhatnagar · Laura Quinn · Antony Higginson · Andrew Plumb · Steve Halligan · Damian Tolan · Roger Lapham · Susan Mallett · Stuart A. Taylor · METRIC study investigators

Abdom Radiol (NY). 2020 Oct;45(10):3036-3045

DOI: 10.1007/s00261-020-02405-w

Crohn’s disease (CD) is a chronic inflammatory bowel disease affecting individuals of any age that can cause significant morbidity and impact in quality of life (1). Imaging is crucial for the diagnosis and plays an essential role in the management of these patients, allowing the disease activity assessment and detection of complications. In fact, all newly diagnosed CD patients should undergo small bowel assessment, either with intestinal ultrasound (IUS), MR enterography (MRE) and/or capsule endoscopy (2).

The METRIC was a prospective multicenter cohort study comparing diagnostic accuracy, observer variability, acceptability, diagnostic impact and cost-effectiveness of MRE and IUS in newly diagnosed or relapsing CD patients (3). In the main analysis, MRE outperformed IUS in the detection, extent and activity of small bowel CD, while IUS was more sensitive in the detection of colonic disease in newly diagnosed patients (4).

In this substudy of the METRIC trial, the authors aimed to evaluate interobserver agreement for small bowel ultrasound in newly diagnosed and relapsing CD. 38 patients (11 new diagnosis and 27 relapses) were recruited from two sites. A second ultrasound examination was performed by one of a pool of six practitioners (5 radiologists and one sonographer) with variable levels of experience – ranging from 3 to 20 years of experience in gastrointestinal imaging and from 50 to >1000 small bowel ultrasound exams performed at the beginning of the trial. The presence, activity and location of small bowel and colonic disease were recorded. Comparisons were made against the reference standard (previously defined on the METRIC trial) and between practitioners. Against the reference standard, agreement for small bowel disease presence was 82% in new diagnosis and 81% in the relapsing group. For colonic disease presence the agreement was 64% in new diagnosis and 78% in relapsing group. Agreement between practitioners was 84% for small bowel and 87% for colonic disease presence.

The latest ECCO-ESGAR Guideline for the Diagnostic Assessment in IBD, published in 2019, emphasizes the role of MRE and IUS in the assessment of CD patients. CT enterography should largely be reserved for the emergency setting due to radiation exposure (2).

IUS has various advantages over MRE – it does not require oral or intravenous contrast, scanning times are faster and it is widely available. Also, while both methods are well tolerated by patients, IUS is generally preferred to MRE (5). By design, IUS is operator dependent and therefore interobserver variability has always been regarded as an important limitation. These results show that IUS evaluation in CD is reproducible and performs well against the reference standard in identifying CD presence, even amongst practitioners with different levels of experience. In this way, these results help to pave the way for wider implementation of IUS in CD in clinical practice.

On the other hand, against the reference standard, the agreement on disease activity on a per-patient basis was only fair. Although there are MRE-based disease activity scores with high accuracy, currently there are no validated scores for IUS (6,7). Further research is needed to find a reliable IUS activity index.

Radiological evaluation of pancreatic cancer: What is the significance of arterial encasement >180° after neoadjuvant treatment?

P. Mayer, A. Giannakis, M. Klaub, M.M. Gaida, F. Bergmann, H. U. Kauczor, M. Feisst, T. Hackert, M. Loos

European Journal of Radiology Volume 137, 109603, 2021

https://doi.org/10.1016/j.ejrad.2021.109603

Pancreatic ductal adenocarcinoma (PDAC) is a malignant neoplasm with poor prognosis and only 4% 5-years survival due to precocious disease spread beyond pancreatic borders, with encasement of near vessels (1). Currently, the only potentially curative therapy is complete surgical resection. However, less than 30% of patients with newly diagnosed PDAC are eligible for it. In the absence of distant metastases, pancreatic cancer resectability is determined by the degree of tumor vascular infiltration.

Arterial encasement >180° of the celiac axis, the superior mesenteric or the common and proper hepatic arteries makes non-treated PDAC unresectable according to current classifications (2).

Therapeutic planning may be troublesome in patients with PDAC after neoadjuvant therapy (NAT) due to the difficulty in differentiating real arterial infiltration by neoplastic tissue from fibro-inflammatory perivascular alterations in post-therapy CT-scans: an encasement >180° may not correlate with vascular infiltration (3,4).

Mayer and colleagues tried to provide criteria to establish vessels infiltration on CT-scans in Patients with more than 180° arterial encasement after NAT. 70 CT scans were analyzed before and after NAT and the interpretation was then confirmed by surgical and histological examinations.
According to the surgical findings, patient arteries were divided into two groups: 51 non–invaded arteries and 24 invaded arteries.

The CT evaluations and the statistical analyses of the acquired data identified two parameters that held high negative predictive value (NPV) in differentiating invaded and non-invaded arteries after NAT.
The first is an arterial encasement >270°. In this series, this was the most appropriate threshold in differentiating invaded and non-invaded blood vessels after NAT (NPV=89.3%). In fact, only 24 out of 75 analyzed arteries with post-NAT >180° encasement were actually invaded by the tumor.
The second is a solid soft tissue contact with arteries <26 mm: in this case, the arteries are less likely to be infiltrated (NPV=87.5%).
After NAT, non-infiltrating lesions showed a significant decrease in length of solid tissue contact with blood vessels (≥20%), a marked reduction in size (≥20%), and presented significantly lower contiguity scores than infiltrating lesions.
Another interesting result of this study concerns the post NAT levels of Carbohydrate 19.9 antigen (CA 19-9) and of Carcinoembryonic antigen (CEA). In fact, the levels of these serum tumor markers represent another aspect to be taken into consideration in differentiating between non-invaded and invaded arteries, with optimal cut-off values of > 73 U/ml for CA 19-9 and 2,3 mcg/L for CEA.

Prognostic role of spleen volume measurement using computed tomography in patients with compensated chronic liver disease from hepatitis B viral infection

Yoo J., Kim S.W., Lee D.H., Bae J.S., Cho E.J.

European Radiology. March 2021; 31(3):1432-42.

DOI: 10.1007/s00330-020-07209-6  PMID: 32880698

Predict the development of decompensation (considered as the presence of variceal bleeding, ascites, jaundice, or encephalopathy) in patients with compensated chronic liver disease (cCLD) is important because it is one of the main determinants of survival (1). Furthermore, the risk of hepatocellular carcinoma (HCC) (2,3) or death (4,5) is higher in the decompensated stage than in compensated one.

The authors of this study have investigated retrospectively the prognostic role of spleen volume measurement in patients with compensated chronic liver disease (cCLD) from chronic hepatitis B (CHB), particularly regarding the occurrence of HCC, the development of decompensation, and overall survival (OS), since splenomegaly is a common finding in patients with cirrhosis and portal hypertension (6).

A total of 584 patients underwent contrast-enhanced multiphasic liver CT scan, including quadruple-phase with pre-contrast, late arterial phase (LAP), portal venous phase (PVP), and delayed phase (DP) for surveillance of HCC were included. The inclusion criteria include patients with CLD from CHB with Child-Pugh class A liver function without ascites, previous history of HCC treatment or hepatic decompensation, and absence of concomitant serious medical illness; who pursued at least more than 5 years of follow-up after the CT examination date without HCC occurrence, the development of decompensation, or death.

The PVP images were used to measure the spleen. Unidimensional measurement size was performed by a board-certified radiologist. The longest dimension between the poles of the spleen was manually measured and recorded. The same radiologist, performed volumetric analysis independently using a semi-automated volumetric software program that was approved for liver volumetry. In each patient, less than 1 minute was needed for spleen volume measurement.

Spleen length and volume were successfully measured in all patients. Mean spleen length ± standard deviation (SD) was 116.1 ± 23.3 mm, and mean spleen volume ± SD was 333.0 ± 216.4 mL (range, 40.5– 2206.1 mL).

During a median follow-up period of 92 months, HCC occurred in 114 of 584 patients (19.5%), 30 patients (5.1%) experienced hepatic decompensation, and 23 patients (3.9%) died. Multivariate analysis revealed that spleen volume was an independent prognostic factor for HCC occurrence (hazard ratio (HR) = 1.01, 95% confidence interval = 1.01–1.01, p = 0.009), was a significant predictive factor for hepatic decompensation (HR = 1.01, 95% CI = 1.01–1.01, p = 0.005) and also was an independent predictor of OS (HR = 1.01, 95% CI = 1.01–1.01, p = 0.007). The optimal cutoff spleen volume was set at 532 mL for HCC occurrence, 656.9 mL for the development of decompensation, and 741.1 mL for OS. Conversely, the results after multivariate analysis were not statistically significant for spleen length. In this study, larger spleen volume was a significant risk factor for the development of HCC, decompensation, and death in CHB patients.

Interobserver Variability and Diagnostic Performance of Gadoxetic Acid–enhanced MRI for Predicting Microvascular Invasion in Hepatocellular Carcinoma

Min J.H., Lee M.W., Park H.S., Lee D.H., Park H.J., Lim S., Choi S.-Y., Lee J., Lee J.E., Ha S.Y., Cha D.I., Carriere K.C., Ahn J.H.

Radiology 2020; 297:573–581. https://doi.org/10.1148/radiol.2020201940

Hepatocellular carcinoma (HCC) is the sixth most prevalent neoplasm and the third leading cause of cancer death [1]. The progression of HCC is rapid with high invasiveness, and among the current treatment strategies, radical surgical resection is the preferred treatment strategy in patients with localized disease and preserved hepatic function. Despite optimal surgical resection, the outcome of HCC patients remains poor, and the postoperative 5-year recurrence rate of HCC is approximately 70%, of which two-thirds of all recurrences occur within 2 years after surgery and <35% after liver transplantation [2-4]. Microvascular invasion (MVI) is a histopathologic feature of tumor aggressiveness, observed in 15-57% of HCC, and it is considered as a strong predictor that leads to a high recurrence rate and poor survival rate in HCC patients [5]. An accurate preoperative noninvasive evaluation of the MVI presence can contribute to the optimal treatment strategy and prognosis stratification in patients with HCC based on risk-benefit assessment [6]. Despite several improvements in imaging technique and radiological diagnosis, the preoperative prediction of MVI remains challenging in clinical practice and different imaging features have been proposed as predictors of MVI.

A recent study on the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (MRI) for predicting MVI in patients with diagnosis of HCC has been published by Min et al [7]. In this retrospective analysis, the Authors have evaluated the interobserver agreement and diagnostic performance in the preoperative MRI assessment of the presence of MVI in patients with surgically confirmed HCCs smaller than 5 cm. In their cohort of 100 patients, the most common cause of chronic liver disease was hepatitis B virus (88%) and 51 of 100 patients (51%) had liver cirrhosis. The mean tumor size was 2.8 cm ± 0.9 (62% <3 cm and 38% >3 cm) and MVI have been diagnosed in 39 of the 100 HCCs (39%) at histopathology. Considering the size of the tumor, HCCs >3 cm had a higher frequency of MVI than HCCs measuring 3 cm or less (55% vs 29%, respectively).

Imaging analysis was performed by eight independent fellowship-trained radiologists. Different imaging features for the prediction of MVI have been assessed, and among these nonsmooth tumor margin showed the highest sensitivity (38-90%) and peritumoral arterial phase hyperenhancement showed the highest specificity (84-98%) for all readers. The specificity (95-100%) and positive predictive value (67-100%) were higher compared with other combinations of imaging features for all reviewers (irregular rim-like enhancement in the arterial phase, peritumoral hepatobiliary phase hypointensity). The analysis revealed a fair-to-moderate overall interobserver agreement (k range: 0.24-0.41) regarding each MVI imaging feature or their combination and MVI probability between observers.

Diagnostic performance of each reader was modest for MVI prediction (area under the receiver operating characteristic curve [AUC] range, 0.60–0.74). The sensitivity for the diagnosis of MVI ranged from 15% to 69%, and the specificity ranged from 57% to 92%. Interestingly, when considering the size subgroup, the interobserver agreement for MVI probability was poor-to-fair and there were no differences in interobserver agreement for MVI according to the readers’ experience with regard to HCCs measuring 3 cm or less, while for HCCs larger than 3 cm, five more experienced readers showed higher sensitivity for the diagnosis of MVI. In the MVI probability categorization, more experienced readers showed higher agreement than less experienced readers.

Quality of same-day CT colonography following incomplete optical colonoscopy

O’Shea, A., Foran, A. T., Murray, T. E., Thornton, E., Dunne, R., Lee, M. J., & Morrin, M. M. (2020)

European Radiology, 30(12), 6508-6516. https://doi.org/10.1007/s00330-020-06979-3

Performing a complete colonoscopy is vital for identifying colorectal malignancy and minimising polyp miss rates in all segments of the colon¹. Unfortunately the success of colonoscopy is dependent on several factors including adequate bowel preparation and patient tolerance². Estimated rates of incomplete colonoscopy vary between 4 and 24%¹. Thankfully, CT colonography (CTC) is not as significantly limited by these factors. ESGAR consensus guidelines now state that CTC is the recommended tool for imaging the colon in the setting of incomplete endoscopic colonoscopy^3-5. Increasingly centres with capacity can offer patients CT colonography on the same day or next day following incomplete optical colonoscopy, but there have been some questions regarding the quality of these studies⁶.

A group of radiologists at the Beaumont hospital in Dublin conducted a retrospective review of 245 patients who underwent same-day CT colonography following an incomplete optical colonoscopy, in order to study the diagnostic quality of these scans.

Following incomplete colonoscopy, patients underwent a low dose non-contrast CT scan of the abdomen and pelvis to exclude a perforation. Once they had recovered from any sedation administered at the time of colonoscopy faecal tagging was commenced using 30mL Gastrografin in 1 pint of water, consumed over 20 minutes. CTC was scheduled for approximately 3 hours later.

In order to evaluate the quality of the same-day CTC studies, the colon was divided into thirteen sections extending from rectum to caecum. Each section was evaluated for adequacy of luminal distension, residual fluid volume and density, residual stool, and adequacy of faecal tagging. A scoring system was devised by a consultant radiologist, then taught to and employed by a single radiology fellow who reviewed all 245 scans. Scores for each aspect of diagnostic quality were allocated to each of the thirteen sections of the colon.

Results showed that the median residual volume of fluid in each examined segment was estimated at less than 25%, and the mean score for tagging of residual fluid was between 0 (complete) and 1 (incomplete but adequate). Minimal residual stool was noted in the large bowel and, when present, was most frequently identified in the rectum or proximal sigmoid colon. Finally, luminal distension in all segments showed median values ranging from 3 to 4 on the semi-quantitative scale, indicating either “entire segment seen” or “well distended”. Contrast reached, at least, the left hemi-colon in 84% of patients and the rectum in 57% of patients. Perhaps most importantly, 99% of studies did not require a repeat CTC or optical colonoscopy.

Overall the results give strong evidence for the concept that same-day CT colonography is a high quality study which can provide complete colonic evaluation following an incomplete colonoscopy.

The benefits of offering same day CTC to patients who undergo incomplete colonoscopy are clear. Patients are saved having to present for another appointment, and enduring the uncomfortable process of bowel preparation for a second time. The study recognises this method’s potential to reduce patient ‘attrition’, by which a proportion of patients may never return for a repeat study, potentially leading to a delayed or missed diagnosis.

Two-Dimensional-Shear Wave Elastography with a Propagation Map: Prospective Evaluation of Liver Fibrosis Using Histopathology as the Reference Standard

Dong Ho Lee, Eun Sun Lee, Jae Young Lee, Jae Seok Bae, Haeryoung Kim, Kyung Bun Lee, Su Jong Yu, Eun Ju Cho, Jeong-Hoon Lee, Young Youn Cho, Joon Koo Han, Byung Ihn Choi

Korean J Radiol. 2020 Dec;21(12):1317-1325. https://doi.org/10.3348/kjr.2019.0978

The liver responds to sustained insult by a scarring process known as fibrosis. A stiff liver can regenerate when managed appropriately in its early stages but when gone unrecognised or untreated, can progress to irreversible cirrhosis and hepatocellular carcinoma.

Transient elastography (TE), point shear wave elastography (SWE) and two-dimensional (2D) SWE of supersonic shear imaging (SSI) are ultrasound (US) techniques that have been developed to provide a reliable non-invasive measurement of liver stiffness comparable to the reference diagnostic standard which is fibrosis stage obtained from liver biopsy specimens. Accurate values for liver stiffness are achieved by using a measurement reliability index with point SWE and propagation map in 2D SWE. SWE techniques, unlike TE, can provide B-mode and elastography exams concurrently. Other limitations of TE include small sample volume and physical impediment to push-pulse technique in patients with ascites and obesity [1].

In this prospective review, fibrosis detection and staging by 2D SWE using a propagation map was compared to results of histopathological specimens obtained from the same patients. The final study population comprised of 114 patients from two separate hospitals with a male to female ratio of 0.5:1 who met the following inclusion criteria: a) age between 20 – 85 years, b) liver biopsy indicated to ascertain cause of diffuse liver disease, c) valid informed consent and d) no bleeding risk (platelet count > 80,000/mm³, INR <1.5).

One of three radiologists performed US evaluation of the liver parenchyma on all patients prior to liver biopsy. Patients were fasted for at least 6 hours before their scheduled appointment and they were scanned using a curvilinear probe in the supine position with their right arm above their head. Greyscale B-mode was first used to detect any focal lesions. 2D SWE mode was then activated, a 2 x 2 cm sample box was placed 1cm below Glisson’s capsule avoiding large vessels and a shear wave propagation was emitted using an acoustic radiation force while the patient held their breath for 1 second. Smooth parallel lines within the sample box were taken to represent stable measurement conditions. Shear wave propagation and data filling of the sample box was performed three times for each patient with one of the propagation maps having three further measurements taken from smaller 1cm-sized circular ROIs; this amounted to nine values of liver stiffness per patient. An elasticity map was then used to measure degree of liver stiffness in kilopascal (kPa).

Out of the 9 values per patient, median measurements were selected for further analysis. Values >30% of the interquartile range (IQR) were considered unreliable. The rate of unreliable measurements in this study was estimated at 7.3%, similar to another study using 2D-SWE with a propagation map which had a rate of 5.2% [2] and less than another study using 2D-SWE with SSI which had a rate of 23% [3].

Submucosal Enhancing Stripe as a Contrast Material–enhanced MRI-based Imaging Feature or the Differentiation of Stage T0–T1 from Early T2 Rectal Cancers

Li-Juan Wan, MM* • Yuan Liu, MM* • Wen-Jing Peng, MM • Shuang-Mei Zou, MD • Feng Ye, MD •Han Ouyang, MD • Xin-Ming Zhao, MD • Chun-Wu Zhou, MD • Hong-Mei Zhang, MD

Radiology 2020; 00:1–9

Screening programmes have led to increased detection of early rectal cancers. Patients with early-stage rectal cancers can now be treated with chemo-radiotherapy or transanal endoscopic mucosal surgery (TEMS) rather than a total mesorectal excision which can carry significant morbidity. The treatment decision is often guided by local staging using MRI. Currently T0-T1 and T2 tumours are differentiated by assessing the status of the muscularis propria (SMP) on high resolution T2 weighted imaging.

This paper introduces a novel and interesting radiological sign to differentiate T0-T1 from T2 rectal tumours - the submucosal enhancing stripe (SES). The submucosa of the rectum contains an abundance of vessels, which enhances on administering intravenous contrast, forming a continuous enhancing stripe. This stripe is lost or interrupted by a rectal tumour which crosses through the submucosa into the muscularis propria (i.e a T2 tumour). The main aim of the study was to assess how good the SES is at differentiating T0-T1 from T2 tumours and to compare which is better at differentiating T0-T1 and T2 rectal tumours; the conventional method of assessing the SMP or the novel SES.

The authors performed a retrospective study of rectal MRI scans performed at their institute from 2012 to 2019. Only T0-T1 and T2 tumours with no prior chemo-radiotherapy which then underwent surgical resection within 3 weeks of the MRI were included. To further increase the validity of the findings only early T2 tumours were included, as the authors felt larger T2 tumours that infiltrated into the outer layer of muscularis propria could be easily distinguished from T1 tumours.

The authors provide a thorough description of the inclusion and exclusion criteria, their MRI imaging protocol and the methodology of how the scans were reviewed. 431 patients met the inclusion criteria and their scans were reviewed independently by two GI radiologists with 38 years of rectal MRI experience between them. The imaging features which were assessed included tumour location, length, circumference, shape, distance from the anal verge, if the SES was present or absent and if the SMP was regular or irregular.

249 patients had T0, Tis, T1 tumours and 182 T2 rectal tumours. In the T0-T1 group 84% had an intact SES whereas in the T2 group 92% had a disrupted SES.

The diagnostic accuracy, sensitivity and specificity for the SES was 87% (95% CI: 84, 90), 84% (95% CI: 79, 88) and 92% (95% CI: 87, 95) respectively. For the SMP the diagnostic accuracy, sensitivity and specificity was 67% (95% CI: 63, 72), 63% (95% CI: 57, 69) and 73% (95% CI: 66, 79) respectively. Cohens Kappa Coefficient was used to calculate inter observer agreement. There was excellent inter observer agreement with the SES (indicating that it is a reproducible sign) whilst with SMP it was only moderate.

Adhesive Small Bowel Obstruction: Predictive Radiology to Improve Patient Management

Marc Zins, Ingrid Millet, Patrice Taourel

Radiology 2020; 00:1-13. https://doi.org/10.1148/radiol.2020192234

Dr. Bruno Giesteira, 2^nd year Radiologist Resident, Department of Radiology, Oporto Hospital and University Center, Oporto (Portugal).
Prof. Dr. Manuela França, Hospitalar Assistant and Head of Radiology Department, Oporto Hospital and University Center, Oporto (Portugal).

Small bowel obstruction (SBO) is a main reason of emergency room admissions, with adhesions being its most common cause. The management of SBO has been changing in recent years, with increasing non-surgical attitude instead of performing immediate surgery. Clinical and laboratory signs lack sensibility in predicting the need of surgery and, conversely, imaging studies have been playing a major role for treatment guidance. Imaging is performed to confirm the diagnosis of SBO, to locate the site of obstruction, to identify its cause and to evaluate for potential complications. In this paper, Zins et al. review the ability of imaging to personalize management decisions, namely, highlighting predictors of ischemia, bowel infarction and need for bowel resection, differentiators of open-loop from closed-loop adhesive SBO and, moreover, how to distinguish single band from matted adhesions.

In spite of being widely used for evaluating small bowel loop dilation or air-fluid levels, abdominal radiographs lack sensibility and specificity compared to CT scans and are unable to identify the cause of SBO and its main complications. Nowadays, abdominal radiographs are not recommended as part of the work-up of suspected SBO by the American College of Radiology (ACR) appropriateness criteria ⁽¹⁾ and Bologna guidelines ⁽²⁾. Ultrasound examination also fails in the identification of the transient point and the cause of obstruction. Therefore, it is not used as a first-line imaging technique, except in pregnancy and pediatrics patients.

CT is the modality of choice for patients with a suspected SBO, being strongly recommended in both ACR appropriateness criteria ⁽¹⁾ and Bologna guidelines ⁽²⁾. The authors suggest a multidetector CT protocol, with unenhanced acquisition plus intravenous contrast-enhanced acquisition on a portal venous phase, with multiplanar reconstruction. Oral contrast administration is not advised. Although not recommended by the ACR guidelines, the acquisition of unenhanced images may increase the detection of decreased bowel wall enhancement ⁽³⁾. Furthermore, they allow detecting increased bowel wall attenuation related to ischemia and transmural necrosis ⁽⁴⁾.

Although MRI is nearly as accurate as CT imaging, it is limited by low availability and the need of patient cooperation.

Strangulation with ischemia is the main source of morbi-mortality in patients with SBO and it requires emergent surgery. Determining signs of ischemia is the most important task for the radiologist. A recent meta-analysis concluded that decreased bowel wall enhancement had the highest specificity for strangulation and the absence of mesenteric fluid was reliable to exclude the diagnosis ⁽⁵⁾. Three major signs were associated with ischemia: decreased bowel wall enhancement, mesenteric haziness and closed-loop obstruction ⁽⁶⁾. The presence of at least two of these signs had a high positive likehood ratio and suggest a need for surgical intervention, whereas their total absence had a high negative predictive value suggesting non-surgical management.

CT findings potentially associated with bowel resection include parietal pneumatosis, lack of bowel wall enhancement in portal venous phase, and increased bowel wall attenuation at unenhanced CT. The later has high specificity for necrosis but low sensitivity and, when present, it indicates irreversible ischemia and requires emergent bowel resection ^(4,7).

The differentiation of the mechanism of adhesive SBO, as open-loop or closed-loop variants, is important because closed-loop adhesive is associated with a higher risk of bowel ischemia and failure of non-surgical treatment. The diagnosis of closed-loop SBO on CT is challenging. Characteristically, fusiform tapering of the loops is seen at the two adjacent transition zones as well as indirect signs, such as a C-/U-shaped bowel loop and radial distribution of the loops pointing to the transition zone. It is not straightforward that identifying a closed-loop SBO requires surgical intervention. In fact, a distance greater or equal to 8 mm between the two transition zones was predictive of a successful nonoperative treatment ⁽⁸⁾, still additional studies are needed.

Usually, single band adhesion is more common in the absence of previous abdominal surgery and is more likely to cause strangulation. Extraluminal bowel compression by the band may be seen at the transition zone (fat notch sign) ⁽⁹⁾. In turn, matted adhesions cause obstruction by angulation, kinking and twisting the bowel ⁽¹⁰⁾.

MRI Findings of Liver Parenchyma Peripheral to Colorectal Liver Metastasis: A Potential Predictor of Long-term Prognosis

Authors: Nakai Y, Gonoi W, Kurokawa R, Nishioka Y, Abe H, Arita J, Ushiku T, Hasegawa K, Abe O.

Journal: Radiology. 2020 Dec;297(3):584-594.
doi: 10.1148/radiol.2020202367.
Epub 2020 Oct 6. PMID: 33021892.

Curative liver resection is recommended as the most effective therapy for colorectal liver metastasis (CRLM). Histopathological analysis of resected CRLM usually aims to confirm malignancy or evaluate surgical margins, but other aspects such as vascular or bile duct invasion have been proposed as poor prognostic factors after resection of CRLM (1,2).

For an accurate surgical planning, gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI is usually performed. Some authors have tried to predict long-term prognosis after hepatectomy based on some MRI findings, such as delayed tumor enhancement (3), but there have been no reports of prediction of microscopic vascular invasion of CRLM based on Gd-EOB-DTPA–enhanced MRI.

The authors aim to investigate whether EOB-DTPA–enhanced MRI findings peripheral to the CRLM could be used to predict pathologic vessel invasion, overall survival (OS) and recurrence-free survival (RFS) after curative surgery in patients without neoadjuvant chemotherapy. Their retrospective study included 148 metastases in 106 patients, excluding patients with five or more metastases, CRLM of <10 mm and portal vein embolization before surgery. Some clinical and analytical variables were recorded, such as the primary site of the tumor, primary tumor nodal status, history of extrahepatic disease, history of synchronous liver metastasis, number of hepatectomies, history of adjuvant chemotherapy, and preoperative serum carcinoembryonic antigen (CEA) level.

Imaging follow-up was performed every three months for the first two years, and then every six months. The MRI dynamic study involving liver acquisition included double arterial and portal venous phase or arterial, portal venous, and delayed phase images. Hepatobiliary phase images were obtained.

The MRI images were examined by three independent abdominal radiologists who were blinded to the clinical and pathologic findings, and they evaluated for number and diameter of CRLMs, presence or absence of early enhancement of liver parenchyma, reduced Gd-EOB-DTPA uptake area and bile duct dilatation peripheral to the tumor.

Histologic specimens were reevaluated and analyzed by a board-certified pathologist also blinded to the clinical and imaging findings, to assess surgical margin status and the presence or absence of portal vein, hepatic vein and bile duct invasion.

Authors developed two multivariable analysis model. In the first, they analyzed separately three findings: the presence or absence of early enhancement, reduced Gd-EOB-DTPA uptake and bile duct dilatation. In the second model, they included the integrated MRI finding of CRLM positive for one or more of the three findings.

Bile duct dilatation peripheral to the tumor was associated with pathologic portal vein invasion (sensitivity, 12 of 50 [24%]; specificity, 89 of 98 [91%]; P = .02), bile duct invasion (sensitivity, 8 of 19 [42%]; specificity, 116 of 129 [90%]; P = .001), poor RFS (P = .03; hazard ratio [HR] = 2.4 [95% confidence interval {CI}: 1.3, 4.2]), and poor OS (P = .01; HR = 2.4 [95% CI: 1.2, 4.9]).

Early enhancement and reduced Gd-EOB-DTPA uptake peripheral to the CRLM were not associated with pathologic vessel invasion or RFS and were associated with OS only in univariable analysis. However, a combination of early enhancement and reduced Gd-EOB-DTPA uptake peripheral to the CRLM with bile duct dilatation at MRI was predictive of poor OS (P = .001, HR = 3.3).

The main weakness of this study is its retrospective design, and some limitations in the patient’s selection and evaluation. In patients who had undergone multiple hepatectomies, imaging findings at the time of the other hepatectomies were not reviewed. Besides, they did not evaluate tumors smaller than 10 mm and patients with neoadjuvant chemotherapy were not included. Furthermore, different patterns of recurrence were not evaluated. Future studies should investigate the tumor recurrence pattern and whether neoadjuvant chemotherapy improves prognosis in patients with tumors showing abnormal peritumoral imaging findings.

Comparison of a coaxial versus non-coaxial liver biopsy technique in an oncological setting: diagnostic yield, complications and seeding risk. 

Nicos Fotiadis, Katja N. De Paepe, Lawrence Bonne,Nasir Khan, Angela Riddell, Nicholas Turner, Naureen Starling, Marco Gerlinger , Sheela Rao, Ian Chau, David Cunningham & Dow-Mu Koh

Eur Radiol 30, 6702–6708 (2020).
https://doi.org/10.1007/s00330-020-07038-7

Interventional radiology skills form workload for many gastrointestinal radiologists.  The complexity of oncological therapies continues to increase, requiring routine sophisticated tumour analysis for molecular and genomic analysis, such as for deficient mis match repair in colorectal carcinoma, which indicates chemotherapy resistance of tumours to 5-FU based chemotherapy.¹ Since the liver is a common site for metastasis the optimal method for tissue sampling must be considered.  While CIRSE has issued guidance on percutaneous needle biopsy in 2017, no specific guidance was issued regarding the optimal needle combination (Coaxial vs Non-coaxial).² However they noted that coaxial systems have no increase in complications and may reduce procedure time compared with non-coaxial techniques.

The Royal Marsden research group (London, UK) performed this important comparative study to assess the optimal technique for coaxial needle biopsy of the liver, comparing diagnostic yield, safety and seeding risk with a coaxial percutaneous liver biopsy (C-PLB) and a non-coaxial (NC-PLB) liver biopsy technique in a cancer patient cohort.   

The group evaluated the outcomes in 741 patients undergoing 932 liver biopsies with 9.1% under CT guidance with the remaining 90.9% using ultrasound with patients given fentanyl and optional midazolam for comfort.  Patients had a full range of malignancies, with the commonest being Colorectal (20.4%), Breast (15.5%) and Lung (9%). The operator was able to choose the type of needle and the diameter (C-PLB 15G or 17G vs NC-PLB 16G or 18G) depending on preference and clinical situation. In the group undergoing C-PLB all patients had gelatin pledgets inserted along the needle track for haemostasis at the end of the procedure. All patients without complications were observed for 4 hours prior to discharge. Outcomes and complications were assessed by follow up of patient records and imaging studies.

C-PLB was most commonly performed (72.9% vs 27.1% for NC-PLB) with 18G biopsy diameter selected in 69.1% and 85% respectively.  Diagnostic yield was high (92.6%) with no significant difference in diagnostic yield between C-PLB and NC-PLB or differences in needle diameter. However more cores were obtained in the C-PLB group (median 4 vs 2 in NC-PLB, p<0.001).  

Ileocolic vascular curvature: a new CT finding of cecal volvulus

Authors: Margaret Wong, R. Brooke Jeffrey, Adam N. Rucker, Eric W. Olcott

Journal Abdominal Radiology 2020 Oct; 45(10):3057-3064.

doi: https://doi.org/10.1007/s00261-020-02491-w

Dr. Smarda Magdalini, Radiology Consultant at Computed Tomography Department of Konstantopouleio General Hospital of Athens, Greece

Cecal volvulus constitutes a relatively rare and potentially fatal emergency condition, in need for immediate open surgery. Less invasive methods of treatment (for example operative detorsion, cecopexy and cecostomy) have been proven to be associated with more complications and higher rates of mortality, so they are not usually preferred [1, 2].

The symptoms of cecal volvulus are not specific and therefore, the clinical image can be misleading. Patients often present to the hospital with acute abdominal pain, abdominal distention, nausea, vomiting and reduction – inhibition of stool output, that is, with symptoms of bowel dilatation of any reason [3].

Apart from the aforementioned nonspecific clinical findings, laboratory findings are also not typical for the disease. So, abdominal imaging and specifically imaging evaluation with computed tomography (CT), plays an important role in the early diagnosis of this potentially fatal nosological entity. Several imaging CT features have been proposed so far as indicative of this condition, including the ‘whirl’ sign, the ‘coffee bean’ sign, decompression of the colon distally to the cecum, small bowel dilation, transition point existence, abnormal appendix position (near the midline, with small bowel being lateral to the cecum) and finally, the ectopic position of cecum [4 – 7].

This article focuses on a new CT observation concerning a mesenteric vasculature differentiation in patients with cecal volvulus that has not been described so far in the literature. More specifically, the authors of this article reported a hook-like curvature of distal ileocolic vessels (‘ileocolic vascular curvature’) in the vast majority of patients who had undergone an urgent abdominal CT examination at their Department because of having the aforementioned symptoms, and afterwards, they proved to suffer from this emergency condition. This finding contradicts the normal linear course of ileocolic vasculature encountered in patients without proven cecal volvulus. A patient search was conducted using the Department’s Picture Archiving and Communication System (PACS) throughout 12.5 years and with the selection of keywords relative to the disease in the Department’s existing CT reports, using the institution’s search engine.

A total number of 14 patients with cecal volvulus from the original CT reports were compared with 40 control patients with cecum dilation without volvulus on original CT reports concerning the existence of the above-mentioned CT features, including ileocolic vascular curvature. Among all 8 CT features examined in this quantitative study, only ileocolic vascular curvature and ectopic cecum were independently and significantly associated with cecal volvulus in multivariable regression (odds ratio 178, p = 0.014, and 63, p = 0.013, respectively). In addition, their sensitivity (12/14 [85.7%, 95% CI 57.2–98.2%] and 13/14 [92.9%, 95% CI 66.1–99.8%], respectively) and specificity (40/40 [100.0%, 95% CI 91.2–100.0%] and 38/40 [95.0%, 95% CI 83.1–99.4%], respectively) were high, differing remarkably from the respective percentages of the rest CT features, which approximated 50%.

The most important limitation of this study is the small sample size, also encountered in previously published studies of the same topic, having to do with the infrequent occurrence of this emergency condition. The small number of patients is considered to be the reason for the deviations of findings between this study and the few previously published quantitative studies concerning the same pathology [8, 9]. It should be pointed out as well, that differences in the results among relevant studies may reflect differences in study design (for example, different criteria for the selection of patients taking part in the study). In addition, this study’s low sensitivity and/or specificity of most CT features apart from ileocolic vascular curvature and ectopic cecum may not correspond to reality, since these values could change dramatically with substantially larger sample size.

Contrast-enhanced US with Sulfur Hexafluoride and Perfluorobutane for the Diagnosis of Hepatocellular Carcinoma in Individuals with High Risk
Authors: Hyo-Jin Kang,  Jeong Min Lee , Jeong Hee Yoon, Kyoungbun Lee, Haeryoung Kim, Joon Koo Han
Journal: . Radiology. 2020 Aug 4
DOI: doi.org/10.1148/radiol.2020200115

Dr. Ivo Sá Marques, Resident, Department of Medical Imaging, Coimbra Hospital and University Centre, Coimbra (Portugal).
Dr. Daniel Ramos Andrade, Radiology Consultant, Coimbra Hospital and University Centre, Coimbra (Portugal).
Prof. Dr. Luís Curvo Semedo, Radiology Consultant, Coimbra Hospital and University Centre; Assistant Professor, Faculty of Medicine - University of Coimbra (Portugal).

Contrast ultrasound (CEUS) is increasingly used in the liver given its high accuracy in the differential diagnosis of focal liver lesions. This technique is readily available, cost-effective and has almost no contraindications and adverse events. Its disadvantages are closely related to the ultrasound technique itself. The ultrasound contrast agent available in Europe -  sulphur hexafluoride (SHF) consists of sulphur hexafluoride microbubbles coated with phospholipids, with a diameter of <10 μm that remain strictly intravascular, with no diffusion into the interstice. [2]

Perfluorobutane (PFB) is a contrast agent that contains perfluorobutane microbubbles inside a phosphatidylserine shell (diameter 2–3 μm). They reach the liver in about 15 s, allowing imaging of the hepatic arterial vascularization and are also captured by Kupffer cells in the reticuloendothelial system of the liver, which enables parenchyma-specific liver imaging. This Kupffer phase imaging is generally performed 10 minutes after intravenous contrast media administration, at which time the normal hepatic parenchyma is enhanced. Therefore, malignant lesions containing few or no Kupffer cells are clearly shown as contrast defects in this phase. An advantage of PFB microbubbles over SHF is their ability to resonate with moderate ultrasound pressure without collapsing, which facilitates the scanning of the entire liver in a Kupffer phase for several hours. [3,4]

In this article, Kang et al. compared the enhancement patterns and diagnostic performance of CEUS with PFB and SHF, in the characterization of liver nodules in patients with a high probability of HCC, based on the CEUS Liver Image Reporting and Data System (LI-RADS®) of the American College of Radiology (ACR). CEUS LI-RADS® standardizes the CEUS technique, interpretation, reporting and data collection for patients at risk of developing hepatocellular carcinoma (HCC). [5]

The study included, from February to August 2019, patients older than 18 years old, at risk of HCC, with one or more treatment-naive hepatic observations (>1 cm) of LR -3, LR-4, LR-5 or LR-M according to CT / MRI LI-RADS version 2018 in acceptable diagnostic images obtained 6 weeks before enrolment. Patients with congestive liver disease, an obvious tumour in a vein and severe cardiovascular dysfunction were excluded. First, an operator radiologist studied the observations with the US-SHF and, soon after the degradation of the microbubbles with high mechanical index pulses in B-mode, the study with PFB proceeded with an interval of at least 30 minutes. The dynamic imaging characteristics (arterial phase hyperenhancement, washout time and degree, and echogenicity in the Kupffer phase) were recorded and then later observed by a reviewer. Only LR-5 observations were assumed to be diagnostic of HCC.

43 of the 59 included observations were confirmed as HCCs. Specificity was 100% for both types of contrast-enhanced US exams. PFB-enhanced US provided higher sensitivity (79% and 74%) and accuracy 0.90 and 0.87 for HCC diagnosis compared with SHF-enhanced US (sensitivity, 54% and 58%; p = .01 and p = .048; accuracy, 0.77 and 0.79, p = .01 and p = .04, for the operator and reviewer, respectively) with implementation of diagnostic criteria for CEUS LI-RADS.

Despite most of the malignancies manifesting clear hypoenhancement in the Kupffer phase with PFB, the degree and prevalence of hypoenhancement did not differ between HCCs and non-HCC malignancies, so the Kupffer phase, in isolation, has no increased specificity. However, reassuringly, none of the benign lesions had hypoenhancement in this phase. These findings suggest we can get a more confident diagnosis of malignancy with the Kupffer phase of PFB.

A possible explanation by the authors for the marginally better results of PFB is that high acoustic pressure, which offers higher spatial resolution, may contribute to improved lesion-to-parenchymal echogenicity differences during the late phase, and thus increase the sensitivity.

Observer agreement for small bowel ultrasound in Crohn’s disease: results from the METRIC trial¹
Authors: Gauraang Bhatnagar, Laura Quinn, Antony Higginson, Andrew Plumb, Steve Halligan, Damian Tolan, Roger Lapham, Susan Mallett, Stuart A. Taylor & METRIC study investigators
Journal Abdominal Radiology 45:3036-3045. 2020 Feb 10. DOI: https://doi.org/10.1007/s00261-020-02405-w

The METRIC trial² was a prospective multicentre trial which recently demonstrated the high sensitivity of small bowel ultrasound (SBUS) for both the presence and extent of small bowel Crohn’s disease. Small bowel ultrasound has advantages over magnetic resonance enterography (MRE); it is widely available, cheaper, does not require IV contrast and is generally preferred by patients³. The perceived drawback of SBUS is the high operator dependence to both identify subtle disease but also to localise disease. Whilst Parente et al.⁴ found excellent inter-observer agreement when localising affected segments of bowel in Crohn’s disease, there is a paucity of research assessing inter-observer variability of active disease on SBUS which is particularly important to guide management.

This study by Taylor et al. set out to assess inter-observer variability for the presence, extent and descriptive features of small bowel and colonic Crohn’s disease.

A proportion of patients previously recruited in the METRIC trial underwent a repeat ultrasound by a different practitioner who was blinded to the findings from the previous SBUS as well as other imaging, and all endoscopic and clinical data other than under which cohort the patient was recruited. There were two cohorts, patients with a new diagnosis of Crohn’s disease and patients with established disease and clinically suspected of luminal relapse. The second SBUS was performed on the same day as the first SBUS by one of 6 practitioners (5 radiologists and 1 sonographer trained in SBUS) and assessed disease presence, activity and location with more detailed mural and extra-mural observations for each segment based on a case report form which included the practitioner’s confidence of these findings. Findings in the main METRIC trial protocol such as wall thickening, focal hyperechoic mesentery (with or without fat wrap), isolated thickened submucosa, increased doppler vascular pattern, ulceration or abscess were assessed. Statistical analysis identified the percentage agreement between practitioners as well as prevalence adjusted bias adjusted kappa (PABAK) to assess inter-observer variability.

There was excellent sonographic agreement for small bowel disease presence in both cohorts with an 82% agreement in patients within the new diagnosis cohort and 81% agreement in the relapsed disease cohort, both with substantial agreement upon assessment of kappa coefficient. There was a lower percentage agreement for colonic disease presence in new diagnosis (64%) with fair agreement (κ = 0.27) although there was 78% agreement in the relapsing cohort with moderate agreement (κ = 0.56).  The study also replicated the high levels of sensitivity of SBUS for small bowel disease presence as in the METRIC trial².

There were cases where practitioners agreed with one another, but they were both incorrect when compared to MRE which was likely due to the limitations of SBUS. These include difficulty identifying disease due to patient factors, subtle findings or abnormal disease site. SBUS had limitations when assessing small bowel disease extent in both cohorts (64% agreement in new diagnosed patients and 56% in suspected relapse patients).  There were also much lower kappa values suggestive of slight (relapse cohort) and fair (new diagnosis cohort) agreement in segmental localisation which differs to the aforementioned findings by Parente et al.⁴

The radiologists participating in this study all had a declared subspecialty interest in gastrointestinal radiology, and the sonographer had undergone formal training and performed SBUS routinely, so these results may not be applicable to general radiologists in a non-specialist setting.

Intrahepatic cholangiocarcinoma: pathogenesis, current staging, and radiological findings
Authors: Mohammed Saleh, Mayur Virarkar, Vlad Bura, Raul Valenzuela, Sanaz Javadi, Janio Szklaruk & Priya Bhosale
Journal: Abdominal Radiology, 2020 May 16
DOI: 10.1007/s00261-020-02559-7

Dr. Adriana Mirela Călin-Vainak, ESGAR Social Media Advocate and member of the Education Committee, Affidea Cluj-Napoca/RO
Dr. Vlad Bura, 4^th year radiology resident, University Hospital, Cluj-Napoca/RO

Cholangiocarcinoma, the second most common primary liver malignancy following hepatocellular carcinoma (HCC), represents approximately 3% of gastrointestinal tumors. It comprises a heterogeneous group of malignancies emerging anywhere between the canals of Hering to the main bile duct: intrahepatic-cholangiocarcinoma (ICC) – from proximal bile ducts to the hepatic duct bifurcation, and extrahepatic-cholangiocarcinoma (ECC) – from the bifurcation to the main bile duct. Although ICC’s comprise only 10-20% of cholangiocarcinomas, its incidence is rising as compared to ECCs, according to World Health Organization databases and other national registries.

Imaging plays an important role not only for diagnosis and staging of ICC, but also for management and treatment guidance. In this comprehensive article, the authors discuss epidemiology, genetics, pathogenesis, clinical presentation, multimodal imaging features, staging, treatment options and management of ICC.

The risk factors for ICC are not so well defined as for HCC. However, factors that promote malignant transformation of premalignant conditions (e.g. biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile duct) have been linked to ICC development: liver flukes, chronic biliary and liver diseases, and lifestyle-related aspects causing chronic inflammation and cholestasis.

The clinical picture is nonspecific – abdominal pain – leading to its late diagnosis and fatal outcome (5y-survival as low as 10%). Unlike ECC, ICC rarely causes jaundice and is often asymptomatic. More than 50% of ICCs are unresectable by the time of diagnosis. A fortunate situation is that of cirrhotic patients undergoing HCC-screening, when ICCs can be incidentally depicted.

ICC rarely causes alteration of liver function tests; thus, initial evaluation mostly relies on imaging alone. The use of CA 19-9 tumor marker (>100U/ml) may be a useful addition for the differential diagnosis of ICC, although its sensitivity and specificity vary among the available literature. It is more useful for radical resection assessment and treatment monitoring.

The role of different imaging modalities in diagnosis, staging and post-treatment follow-up of ICC is largely discussed within the review. As ICC causes nonspecific abdominal symptoms, it may be firstly evaluated by US, but US-features are non-specific. Except for small tumors, CEUS may help differentiate ICC from HCC, mostly based on arterial-phase hyperenhancement pattern (homogeneous for HCC, heterogeneous or peripheral rim for ICC). The most common imaging modality for detection, diagnosis and staging of ICC is CT. Typical behavior of ICC on CT includes: irregular margins, capsular retraction, early rim hyperenhancement (arterial phase) and delayed central enhancement (portal and delayed phases).

At MRI, the enhancement pattern of ICC most commonly resembles the one seen at CT. However, different enhancement patterns exist, carry different prognoses and are better depicted at MRI. Additionally, DWI target appearance of the tumor has a diagnostic sensitivity and specificity as high as 80% and 99%, respectively. MRI is also very helpful to determine treatment response in unresectable cases (post-radiotherapy/TACE): treatment-responsive tumors have not been showing significant size decrease, but rather continuous ADC increase on serial MRI. Due to higher spatial resolution, CT is the modality used for surgical planning –  resectability is assessed with greater accuracy than at MRI. CT is also preferred for assessing distant metastasis – most commonly peritoneal, pulmonary and osseous. With the advantage of assessing tumors’ metabolic activity, PET-CT can be more accurate than CT for distant metastasis detection (including lymph node metastasis), possibly altering management for up to 25% of ICC patients.

Comparison of guidelines for diagnosis of hepatocellular carcinoma using gadoxetic acid–enhanced MRI in transplantation candidates

Authors: Sun Kyung Jeon, Jeong Min Lee, Ijin Joo, Jeongin Yoo & Jin-young Park.

Journal: European Radiology. 2020 Apr 25. doi:

https://doi.org/10.1007/s00330-020-06881-y.

Domenico Salvatore Gagliano (radiology resident, University of Palermo, Palermo/IT) and Roberto Cannella (radiologist and PhD student, University of Palermo, Palermo/IT).

Liver cancers occupy the fourth place in the world as cancer-related mortality and the seventh place in terms of incidence according to WHO data [1]. Hepatocellular carcinoma (HCC) represents one of the few cancers that can be diagnosed by imaging without histopathological examination. Currently, four different guidelines – American Association for the Study of Liver Disease (AASLD), which integrated the Liver Imaging Reporting and Data System (LI-RADS) [2]; European Association for the Study of the Liver (EASL) [3]; Asian Pacific Association for the Study of the Liver (APASL) [4]; and Korean Liver Cancer Association-National Cancer Center (KLCA-NCC) [5] – are used worldwide for the diagnosis of HCC. These guidelines have been updated between the years 2017 and 2018. Furthermore, through the Milan criteria, imaging is fundamental in the assessment of patients who can take advantage of the liver transplant, which in practice represents the only definitive therapy (removes HCC and liver disease).

Recently, Jeon et al. [6] retrospectively compared the diagnostic performances of these four guidelines in patients undergoing gadoxetic acid-enhanced MR imaging within three months of liver transplantation, in the absence of previous treatments for HCC. The reference standard was based on histopathological examination of explanted livers. The pre-transplant MR images of 81 patients were independently examined by three board-certified abdominal radiologists. A total of 154 nodules were assesses, including 116 HCCs, 24 dysplastic nodules, 6 FNH-like nodules, 5 combined hepatocellular-cholangiocarcinomas, and 3 hemangiomas.

The study results revealed that the per-lesion specificity for the diagnosis of HCC of AASLD/LI-RADS (97.4%) was the highest compared to EASL (92.1%), KLCA-NCC (92.1%) and APASL (78.9%). Particularly, APASL demonstrated significantly lower specificity compared to AASLD/LI-RADS. However, the sensitivity of APASL (75.9%) and KLCA-NCC (65.6%) was significantly higher than EASL (38.8%) and AASLD/LI-RADS (34.5%). KLCA-NCC resulted in significantly greater accuracy than EASL in classifying patients unsuitable for transplantation (68.4% vs. 31.8% respectively). Based on the Milan criteria for patients’ allocation, APASL (80.2%) and KLCA-NCC (75.3%) provided better accuracy than AASLD/LI-RADS (64.2%) and EASL (64.2%);

These data suggest that KLCA-NCC an APASL guidelines focus more on sensitivity and therefore on early diagnosis of HCC since the most common approach is to treat the tumor with locoregional therapies, while the AASLD/LI-RADS and EASL guidelines prioritize high specificity in order to reduce false positives as much as possible. The difference between these two different approaches is mainly reflected in the washout appearance definition, which in the AASLD/LI-RADS is limited to portal venous phase only when using gadoxetic acid, while KLCA-NCC guidelines also includes the transitional and hepatobiliary phases, thus achieving greater sensitivity. However, the diagnosis of HCC is excluded if there is hyperintensity on T2-weighted imaging, which may suggest cavernous hemangioma.

The difference in terms of specificity between APASL and KLCA-NCC, on the other hand, is likely due to excluded diagnosis of HCC not only after exclusion of hemangioma, but also in presence of targetoid appearance on diffusion-weighted images or contrast-enhanced sequences, which is an imaging feature of intrahepatic cholangiocarcinoma and other non-HCC hepatic malignancies [5]. The definition of targetoid appearance in KLCA-NCC, shared with the AASLD/LI-RADS, allows to increase the accuracy in the diagnosis of non-HCC malignancies.

Moreover, it is important to note that APASL is the only guideline that allows the definitive diagnosis of HCC, regardless for nodule size, while other guidelines can diagnose HCC only for nodules greater than 10 mm in diameter [7].

The combination of high sensitivity and specificity of the KLCA-NCC guideline allows better accuracy in patient allocation for liver transplant and in particular in classifying unsuitable for transplantation (with non-HCC malignancies or HCCs beyond the Milan criteria) compared to European guidelines.

Abdominal CT manifestations of adverse events to immunotherapy: a primer for radiologists

Authors: Ali Pourvaziri1 · Anushri Parakh1 · Pierpaolo Biondetti1 · Dushyant Sahani2 · Avinash Kambadakone1

Journal: Abdominal Radiology (2020) 45:2624–2636

Dr Rajiv B. Karia (Consultant GI/HPB and Interventional Radiologist. Chesterfield Royal Hospital & Nottingham University Hospitals, UK)

Cancer treatment with chemotherapy has been expanded from conventional chemotherapy agents which cause death of rapidly dividing cells to also involve new therapies which target specific molecules or pathways and also more recently immunotherapeutic  agents which rely on the patient’s immune system to act on the neoplastic cells.  As more and more immunotherapies have become approved over last few years these are becoming a mainstream option for variety of advanced malignancies [1]. The adverse effects of these therapies are unique and diverse.  This paper reviewed the radiological findings of the adverse effects and concentrated on the gastrointestinal tract.

Immunotherapeutic agents are either passive or active.  Passive immunotherapy target cancer cells with specific antibodies (prepared outside the body), and do not stimulate the immune system, but cause destruction of the cells by complement mediated response or elicit antibody dependent cellular cytotoxicity (ADCC). Active immunotherapy however, utilises the immune system (humoral and cellular immunity) to fight the tumour.  Recombined interleukins (IL), cytokines, vaccines (e.g. for prostate cancer), and check point inhibitors (CPI) are all examples of these agents. In addition autologous T-cells can be genetically modified to express T-cell receptors (TCR) that recognise tumour antigen or chimeric antigen receptors (CARs).

Immune related adverse events (irAE) are wide spectrum of side effects that arise from immunotherapeutic agents. Check point inhibitors prevent immune system inhibition mechanisms, and hence favour development of autoimmune manifestations. Side effects of conventional cytotoxic agents are generally more predictable, and usually directed to specific organs. Adverse effects discussed in this paper were outlined generally and specific to type of agents used.  It is suggested that irAE appear to be dose dependent with anti-CTLA-4 inhibitors but not with anti-PD/PD-1 inhibitors [2, 3].

The paper illustrates the various presentations of colitis with the use of immunotherapy. Colitis is the most common irAE that often necessitates discontinuation of therapy [4]. There is a mortality rate of approximately 1% and generally occurs 5 to 10 weeks after initiation therapy. Knowing this helps focuses reporting radiologist’s interpretation and direct the report to the most likely aetiology. The paper described the different types and distribution of colitis with good examples together with pointers on how to differentiate with other causes. Interestingly it was described by the authors that CAR T-cell therapy has been implicated in colonic perforations.

Within the hepatobiliary system, two general patterns have been described; hepatocellular and cholestatic [5, 6]. Immune related hepatitis occur between 6 and 14 weeks after initiation of therapy. Ultrasound demonstrates periportal oedema and gall bladder wall oedema. CT demonstrates hepatomegaly, diffuse parenchymal hypo-attenuation and patchy enhancement together with periportal lymphadenopathy. It was suggested by the authors that MRI maybe needed to differentiate parenchymal changes from metastatic disease.  Following discontinuation of therapy and administration of steroids there is regression of the imaging findings [7-9]. The paper also illustrated these findings using dual energy CT.

Pancreatitis related to the immunotherapy can manifest similar to “classic” autoimmune pancreatitis with diffuse enlargement of the gland, stranding in the peripancreatic fat and heterogeneous enhancement pattern. Authors gave pointers to help differentiate this from autoimmune pancreatitis. Imaging illustrations in the paper demonstrate patients on nivolumab and ipilimumab, showing diffuse enlargement with loss of pancreatic lobulations, but with later images following treatment with steroids showing an atrophic pancreas.

The paper also illustrated renal injuries secondary to different immunotherapy together with illustrations of rheumatological and musculoskeletal adverse effects.  Interestingly manifestation of sarcoid like reaction was described in great detail and there was focus on illustrations of how to help differentiate this from progressive disease. These changes have been reported with the use of CPI’s, and involve the abdomen, lungs, skin and lymph nodes. Biopsy may demonstrate non-caseating granulomas [10]. With these changes care must be taken not to over diagnose this benign finding as progressive disease.

Contrast-enhanced ultrasound for the characterization of portal vein thrombosis vs tumor-in-vein in HCC patients: a systematic review and meta-analysis.

Chen J, Zhu J, Zhang C, Song Y,  Huang P. European Radiology. 2020

Portal vein thrombosis (PVT) and tumor invasion of portal vein (TIV) are both possible complications of Hepatocellular carcinoma (HCC). The importance of differential diagnosis consists in different therapies that should be made. In fact, HCC patients with TIV are not eligible for resection or liver transplantation, but only for Sorafenib. The second approach negatively affects the median survival rate, that decreases from more than 60 months to less than 11 months in patients with TIV.

There are many evidences in literature that B-mode and Color Doppler ultrasound are functional for detecting HCC, as well as PVT. According to AASLD 2018 Practice Guideline these procedures are recommended biannually in cirrhosis patients as a screening for HCC. However, the accuracy of US for detecting TIV is not optimal [2-3].

This paper, published in European Radiology by Chen and coworkers in February 2020, aims to provide based evidence advice about the diagnostic value of Contrast-enhanced ultrasound (CEUS) in differentiating TIV from PVT in HCC patients.

Authors performed a systematic review and meta- analysis of seven studies (including 425 patients) selected from PubMed, Embase, Cochrane Library, and Web of Science, published up to the 5^th of May 2019. The risk of biases within the studies included were evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADS 2) tool. The included studies showed a low risk of bias in patient selection and index test categories but might be at risk in the categories of reference standard and flow and timing.Heterogeneity was calculated by I² index; publication bias was evaluated by Deek's funnel plot demonstrating a low risk of bias among studies, p=0.54 Diagnostic value of CEUS in differential diagnosis between TIV and PVT was evaluated by the receiver-operating characteristic (ROC) curve analysis and the computed cumulative value of area under the curve (AUC) was 0.97 (95% CI, 0.95-0.98). The pooled sensitivity and specificity of CEUS in diagnosing TIV were 0.94 (95% CI, 0.89-0.97) and 0.99 (95% CI, 0.80-1.0) respectively Combining the results of I² and sensitivity analysis, the overall heterogeneity was acceptable.
The Fagan plot demonstrated that CEUS increases the probability of diagnosing TIV from 50 to 99% when positive and lowers the probability of malignancy to as low as 5% when negative.

Clinical features and MRI progression of small duct primary sclerosis cholangitis (PSC)

Kristina I. Ringe, Annika Bergquist, Henrike Lenzen, Nikolaos Kartalis, Michael P. Manns, Frank Wacker, Arsteidis Grigoriadis.
European Radiology – May 2020

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disorder with fibrosis of the intrahepatic and/or extrahepatic bile ducts. Histologically periductal fibro-obliterative “onion skin” concentric fibrosis and bile duct strictures are characteristic of the disease, with cholangiographically identifiable duct changes being the hallmark of PSC. Its course is very variable and in a minority of cases can be benign, however in the majority of cases, PSC is a progressive disease, eventually leading to cirrhosis and potential development of cholangiocarcinoma.

To this day it is uncertain whether small duct PSC (sdPSC) represents an early stage of large duct PSC, a mild variant of it or a separate disease condition altogether.

SdPSC is characterized by clinical and histological features of large duct PSC, but with a normal cholangiogram on endoscopic retrograde cholangiopancreatography (ERCP) or magnetic resonance cholangiopancreatography (MRCP). Currently there is no specific disease marker for sdPSC, and histology remains the cornerstone of diagnosis. Histologic features of sdPSC are the same as those of PSC, surrounding the small interlobular and medium-sized bile ducts, along with a reduced number of interlobular bile ducts.

SdPSC is much less common than large duct PSC and has a favorable disease course, with a lower risk of hepatobiliary malignancy, liver transplantation or death.

The aim of this study was two-fold, first to evaluate and describe the clinical and MRI progression of patients with sdPSC, and second to evaluate MRI features associated with disease progression to large duct PSC.

A retrospective dual-center study was carried out from records of 16 patients with a known diagnosis of sdPSC and available MR imaging. Imaging and liver function tests were reviewed in consensus by two radiologists at baseline and follow-up. Due to the retrospective design, the MR protocol was not standardized. In all patients 3D MRCP, 2D MRCP or single shot MRCP sequences were available for dedicated bile duct evaluation. Some patients also had additional imaging in the form of diffusion-weighted sequences (DWI), T2w and T1w pre and post-contrast imaging (liver specific or extracellular). Images were evaluated for bile duct changes, gallbladder findings, parenchymal changes and associated findings such as hilar lymphadenopathy, ascites, varices, portal vein thrombosis and spleen volume.

Baseline MRI showed the commonest findings, with regards to sdPSC, to be inhomogeneous diffusion-weighted signal and enhancement, altered liver morphology and periportal lymphadenopathy. These changes showed pronounced manifestation at follow-up imaging. Unfortunately, no prognostic MRI marker for prediction of large duct PSC development could be determined at baseline imaging.

The progression rate in this study was high in comparison to previously published data, with 55.5% of sdPSC patients with available follow up imaging, progressing to large duct PSC, supporting the theory that sdPSC may be an early stage of large duct PSC, not a seperate entity. The largest study to date, which included 83 patients with sdPSC, showed a progression rate to large duct PSC of 22.9% in a median of 7.4 years. Ringe et al. (2020) propose the longer follow up period (median 10.6 years) and the fact that all available MRCPs were reviewed (not just those of symptomatic patients), as a possible reason for this discrepancy.

Abdominal Imaging Findings in COVID-19: Preliminary Observations

Authors: Rajesh Bhayana , Avik Som, Matthew D Li, Denston E Carey, Mark A Anderson, Michael A Blake, Onofrio Catalano, Michael S Gee, Peter F Hahn, Mukesh Harisinghani, Aoife Kilcoyne, Susanna I Lee, Amirkasra Mojtahed, Pari V Pandharipande, Theodore T Pierce, David A Rosman, Sanjay Saini, Anthony E Samir, Joseph F Simeone, Debra A Gervais, George Velmahos, Joseph Misdraji, Avinash Kambadakone

Journal: Radiology, 201908. 11 May. 2020, doi:10.1148/radiol.2020201908
 

Dr. Damiano Caruso, Young ESGAR, ESGAR Educational Committee, Radiology Department, Sant’Andrea Academic Hospital, Sapienza University of Rome, Rome, Italy.

Dr. Elena Lucertini, ESGAR Member and radiology resident, Radiology Department, Sant’Andrea Academic Hospital, Sapienza University of Rome, Rome, Italy.

Prof. Andrea Laghi, ESGAR Vice President and Director of the Radiology Department, Sant’Andrea Academic Hospital, Sapienza University of Rome, Rome, Italy.

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rapidly spread all over the world and it was declared pandemic on March 2020 [1, 2].

Despite most common clinical symptoms are fever, cough, and dyspnea, several cases of COVID-19 patients with gastrointestinal (GI) symptoms such as diarrhea, nausea/vomiting, abdominal pain have been observed [3].

Angiotensin-converting enzyme 2 (ACE2) receptors, considered the main virus cellular carriers, are highly surface expressed on enterocytes of the small intestine and biliary epithelium, offering a possible explanation of GI manifestations in COVID-19 patients [4, 5].

A recent retrospective cross-sectional study on the GI manifestations of COVID-19 has been published by Bhayana et al. The Authors have enrolled a total of 412 adult patients consecutively admitted at their institution, from March 27 to April 10, who tested positive for SARS-CoV-2.

Abdominal symptoms were reported in 34% of these patients (142/412) and imaging findings of 134 patients (33%) were analyzed by a team of expert abdominal radiologists: radiography, US, CT of the abdomen and pelvis and MRI images were included in data collection.

CT imaging findings includes abnormalities of bowel wall (such as colonic or small bowel thickening, pneumatosis or portal venous gas and perforation), fluid-filled colon, solid organ infarct, pancreatitis and other findings suggestive of hepatitis.

Otherwise, US imaging findings includes presence of biliary sludge in gallbladder lumen, with or without distension, gallbladder wall thickening, pericholecystic fluid, fatty liver, portal venous gas and portal vein thrombosis.

Finally, the Authors compared demographic, clinical, and imaging data between intensive care unit (ICU) patients and other inpatients. The aim of this retrospective study is to investigate abdominal imaging findings in COVID-19 patients.

Statistical analysis revealed on CT scans presence of bowel abnormalities in 31% of patients, including pneumatosis/thickening of bowel wall and portal venous gas; these findings resulted significantly associated with ICU admission (OR 15.5, p=0.01).

Dr. Gisella Guido is a radiology resident at the University of Rome "Sapienza" - Sant'Andrea University Hospital in Rome, attending the second year of residency. Her main field of interest is abdominal and oncologic radiology. She already worked in this area during the residency and considering pursuing her career in oncological radiology.

Comments may be sent to gisella.guido@remove-this.uniroma1.it