P362 Mesenteric fat proliferation and fat edema in magnetic resonance enterography as predictor of long-term disease complications in Crohn’s disease

Abstract

Abstract Background Fibrofatty proliferation of the mesenteric fat is a common finding in magnetic resonance enterography (MRE) in patients with Crohn’s disease (CD). Mesenteric fat is thought to play an active role in inflammation, fibrosis and stricture formation in CD. However, it is unclear whether these findings have a prognostic value in prediction of bowel damage and complications. We aimed to examine the association between mesenteric fat proliferation and inflammation on MRE and risk for hospital admissions and bowel surgery. Methods Patients with established CD diagnosis with at least 1 available MRE imaging data were followed for hospital admissions for CD exacerbation or abdominal surgery. MRE were reviewed by an expert radiologist for various characteristics (intestinal wall thickening and enhancement, stricture, or abscess formation, fibrofatty proliferation and fat edema reflecting fat inflammation). The association between mesenteric fat and outcomes was assessed using the Kaplan Meier method and log rank test. Crude and adjusted Hazard ratios (HR) with 95% confidence interval (CI) adjusting for baseline MRE characteristics (wall thickness and stricture and pre-stenotic dilatation) were estimated from the Cox proportional hazards regression model (R version 4.2.1). Results 159 CD patient charts and MRE imaging data were analyzed. Patients’ characteristics and medication exposure at described in table 1. On initial MRE the frequency of mesenteric fat proliferation was noted in 43 (27.0%) and fat edema in 79 (49.7%). Other MRE features noted were: mild, moderate and severe wall thickening in 72 (45.5%), 47 (29.9%) and 11 (7.0%) patients, respectively. Contrast intestinal wall enhancement was present in 122 (76.7%) patients. Intestinal stricture with pre-stenotic dilatation was noted in 17 (10.7%) patients and abscess and fistula formation was seen in 10 (6.3%) and 11 (6.9%) patients, respectively. During a mean (SD) follow up of 95.7 (39.5) months, 100 (62.9%) and 40 (25.2%) patients underwent hospitalization or surgery, respectively. On survival analysis, fat proliferation was associated with hospitalizations (Fig 1A, p=0.0005) and surgery (fig 1B, p<0.0001), while fat edema was associated with abdominal surgery (Fig 1D p=0.0003) but not with hospitalization (Fig 1C p=0.28). On multivariable analysis of the associations between fat proliferation and surgery and hospitalization remained highly significant (adjusted HR (95%CI) =3.15 (1.57-6.33) and adjusted HR (95%CI) =1.77 (1.06-2.97), respectively. Conclusion in this analysis of baseline MRE features, mesenteric fat proliferation was independently associated with increased risk for abdominal surgery and hospital admission for disease flares.