CT energy spectral parameters of creeping fat in Crohn’s disease and correlation with inflammatory activity https://doi.org/10.1186/s13244-023-01592-6 The article explores the use of CT spectral energy to evaluate creeping fat, a unique abnormal mesenteric tissue associated with Crohn's disease (CD). Creeping fat is a kind of abnormal mesenteric adipose tissue surrounding more than 50% of the intestinal circumference of the bowel affected in Crohn’s disease [1], and not in other inflammatory bowel diseases [2]. It exhibits hyperplasia with increased small round adipocytes, accompanied by vascular proliferation, fibrosis, lymphadenectasis, and stromal cell infiltration [3], and is often considered an anatomic landmark for the resection of affected bowel segments by surgeons [4]. A prospective single-center study was conducted including 80 patients, 40 with a pathology-confirmed diagnosis of Crohn’s disease and 40 patients without inflammatory bowel disease. The inclusion criteria were as follows: (a) patients with a confirmed diagnosis by endoscopy, histopathology, clinical features, diagnostic imaging, and laboratory findings and (b) patients without contraindications or previous adverse reactions to iodine contrast media and who could successfully undergo a dual-energy CT examination. The exclusion criteria were: (a) patients who were scanned in CT angiography and CT venography; (b) patients with poor image quality in dual-energy CTE and artifacts affecting the measurement of creeping fat; (c) patients whose dual-energy CTE examination was not standardized. Contrast-enhanced CT scans were performed in the enteric phase, with the scanning range from the diaphragmatic apex to the perineal bottom. Each CD patient was classified by Montreal classification and Crohn’s disease activity index (CDAI). CDAI < 150 was defined as inactive and CDAI ≥ 150 as active CD [5]. Two radiologists analyzed the CT scans independently and drew regions of interest (ROIs), avoiding blood vessels and lymph nodes. Also for every patient were performed measurements of the subcutaneous fat and normal mesentery. Quantitative spectral parameters included the slope of the Hounsfield unit curve (λHU), normalised fat–water concentration, normalised fat-iodine concentration, and normalised fat volume fraction were obtained. The study showed that all quantitative spectral parameters at the enteric phase were significantly different among mesenteric adipose tissue in the controls, “normal” mesenteric adipose tissue with CD, and creeping fat with CD. There was no significant difference between mesenteric adipose tissue in the controls and “normal” mesenteric adipose tissue with CD. This suggests that dual-energy CT can readily discriminate the abnormal MAT from the normal MAT. The algorithm applied also showed a significant difference in all quantitative spectral parameters between creeping fat in inactive and active CD. On the contrast-enhanced images creeping fat had a higher concentration of iodinated contrast medium in active disease than in inactive diseases. These results suggest that the dual-energy parameters of creeping fat are useful in quantitatively evaluating the activity of CD. Since these parameters are obtained noninvasively, they can be used to monitor disease progression. In conclusion, dual-energy CTE with a series of spectral parameters can accurately distinguish normal MAT and creeping fat and quantitatively evaluate the disease activity of creeping fat in CD being a potentially novel noninvasive tool for evaluating Crohn’s disease. | References:
Anastasiia Zakharova is a first-year radiology resident at The Medical Center "European Radiological Center" of the LLC "Hemo Medica Kharkiv" in Kharkiv, Ukraine and a trainee at “Unidade Local de Saúde do Alto Minho (ULSAM)” in Viana-do-Castelo, Portugal. She graduated in medicine at “Kharkiv National Medical University” in 2023 and has a wide range of interest in diagnostic imaging including abdominal and gastrointestinal radiology. |