Hu Xiao, Ding Jie-Jie, Qian Nian-Xia, Liu Xiao-Dong
Department of Radiology, Tongling Municipal Hospital, Tongling, China.
Department of Gastroenterology, Tongling Municipal Hospital, Tongling, China.
Quant Imaging Med Surg. 2025 Aug 1;15(8):6910-6922. doi: 10.21037/qims-2024-2606. Epub 2025 Jul 29.
Creeping fat (CF), a characteristic structure of Crohn's disease (CD), is closely associated with surgery and prognosis but lacks a unified imaging assessment standard, and endoscopic and serological indicators have limitations in evaluating extra-intestinal lesions. The study aimed to explore the correlation between computed tomography (CT) value distribution changes of mesenteric-surrounding fat in CD and disease activity.
In this study, we retrospectively analyzed CT enterography (CTE) images from 47 pathologically confirmed CD patients and 25 randomly selected controls with suspected inflammatory bowel disease (IBD). Quantitative measurements were obtained for mesenteric adipose tissue density (mean of CT values) along key anatomical landmarks including the mesenteric root, superior mesenteric artery, inferior mesenteric artery, perilesional regions, intestinal stricture, and adjacent branching vascular spaces. Other evaluated parameters included bowel wall thickness, CT attenuation, enhancement patterns, and CF grading. Qualitative evaluations were made by comparing with endoscopic, serological, and histopathological results and simplified CD activity index (CDAI) scores. A patient with concurrent anal fistula underwent magnetic resonance imaging (MRI) examination to compare its detection efficiency of fistula with that of CT examination.
Significant inter-group differences were found in non-contrast mesenteric fat attenuation, mean ΔCT (difference in Hounsfield units between contrast-enhanced CT and non-contrast CT scans) enhancement, bowel wall thickening, mucosal enhancement, CF grading, intestinal stricture, and serological parameters (P<0.05). The moderate-to-severe activity group had the highest mesenteric fat density in the venous phase [mean ΔCT >20 Hounsfield units (HU), P<0.05], especially around lesions. There was a positive correlation between mesenteric fat CT values and images of diseased bowel segments. The mean value of the venous phase ΔCT of the lesion and the mean of the intestinal wall venous phase ΔCT value and intestinal wall stratification were positively correlated (>0.6, P<0.05). ROC analysis showed that the venous-phase ΔCT of perilesional adipose tissue had excellent diagnostic performance [area under the curve (AUC) =0.964] for moderate-to-severe activity CD, with 95.8% sensitivity and 87.5% specificity. The diagnostic efficacy of the venous phase in the vascular space around the lesion ranked second (AUC =0.943). MRI showed superior detection of the anal fistula to that of CT in one patient. Multivariate analysis confirmed it as an independent predictor for moderate-to-severe active CD (P<0.05).
Changes in mesenteric adipose tissue CT values and CF classification can distinguish CD from other IBD, suggesting their utility as another noninvasive diagnostic method for predicting the inflammatory activity of CD and evaluating the scope of surgery.
匐行脂肪（CF）是克罗恩病（CD）的一种特征性结构，与手术及预后密切相关，但缺乏统一的影像学评估标准，且内镜及血清学指标在评估肠外病变方面存在局限性。本研究旨在探讨CD患者肠系膜周围脂肪的计算机断层扫描（CT）值分布变化与疾病活动度之间的相关性。
本研究回顾性分析了47例经病理证实的CD患者及25例随机选取的疑似炎症性肠病（IBD）对照者的CT小肠造影（CTE）图像。对肠系膜根部、肠系膜上动脉、肠系膜下动脉、病变周围区域、肠狭窄及相邻分支血管间隙等关键解剖标志处的肠系膜脂肪组织密度（CT值均值）进行定量测量。其他评估参数包括肠壁厚度、CT衰减、强化模式及CF分级。通过与内镜、血清学及组织病理学结果和简化的CD活动指数（CDAI）评分进行比较进行定性评估。1例并发肛瘘的患者接受了磁共振成像（MRI）检查，以比较其对肛瘘的检测效率与CT检查的检测效率。
在平扫肠系膜脂肪衰减、平均ΔCT（增强CT与平扫CT扫描之间亨氏单位的差值）强化、肠壁增厚、黏膜强化、CF分级、肠狭窄及血清学参数方面，组间差异有统计学意义（P<0.05）。中重度活动组在静脉期肠系膜脂肪密度最高[平均ΔCT>20亨氏单位（HU），P<0.05]，尤其是在病变周围。肠系膜脂肪CT值与病变肠段图像之间存在正相关。病变静脉期ΔCT均值与肠壁静脉期ΔCT值均值及肠壁分层呈正相关（>0.6，P<0.05）。ROC分析显示，病变周围脂肪组织的静脉期ΔCT对中重度活动期CD具有出色的诊断性能[曲线下面积（AUC）=0.964]，敏感性为95.8%，特异性为87.5%。病变周围血管间隙静脉期的诊断效能排名第二（AUC =0.943）。1例患者中，MRI对肛瘘的检测显示出优于CT的性能。多因素分析证实其为中重度活动期CD的独立预测指标（P<0.05）。
肠系膜脂肪组织CT值变化及CF分级可将CD与其他IBD区分开来，提示其作为预测CD炎症活动度及评估手术范围的另一种非侵入性诊断方法的实用性。
