Prevalence and clinical significance of sonographic evidence of mesenteric fat alterations in Crohn's disease

Background: Mesenteric adipose tissue hypertrophy is a frequent sonographic finding in Crohn's disease (CD). This study assessed its sonographic prevalence, the correlation with the degree of clinical or biochemical activity of the disease, and its impact on disease outcome in CD patients. Methods: In all, 185 consecutive CD patients underwent bowel ultrasound to assess the presence of mesenteric fat tissue alteration as well as thickness and echopattern of the bowel wall, site and extent of CD, and presence of stenosis, fistulas, and abscesses. Clinical and biochemical parameters of disease activity were also assessed. Multiple logistic regression analysis was used to identify variables related to mesenteric adipose tissue alteration. Results: Mesenteric adipose tissue alteration, detected in 88 (47.6%) patients, showed a significant correlation both with clinical and biochemical CD activity and with internal fistulas, bowel wall thickness, and length of thickened bowel wall. Logistic regression analysis showed that internal fistulas (odds ratio [OR] = 13.5), thickened bowel wall (OR = 7.6), C-reactive protein (OR = 6.1), CD Activity Index (CDAI) (OR = 3.1), and length of diseased bowel walls (OR = 2.6) were significantly associated with mesenteric adipose tissue alteration. Of the 111 patients with quiescent CD, 22 showed mesenteric adipose tissue hypertrophy. These patients did not show increased risk of relapse compared with quiescent patients without mesenteric fat alteration. Conclusions: Mesenteric adipose tissue alteration is correlated with biochemical and clinical activity of CD and with internal fistulas and increased bowel wall thickness. In quiescent CD, mesenteric hypertrophy does not appear to be a risk factor of relapse.