Magnetic resonance evaluation for small bowel strictures in Crohn's disease: comparison with balloon enteroscopy.

Abstract

Magnetic resonance (MR) imaging is the recommended technique for detection of small bowel lesions in Crohn's disease. We aimed to evaluate the impact of stricture findings obtained by MR imaging on patient outcomes using balloon-assisted enteroscopy (BAE) as a reference. Two hundred Crohn's disease patients undergoing both MR enterocolonography and BAE were prospectively followed up for at least 1year. The presence of strictures detected by MR enterocolonography was compared with endoscopic findings. Moreover, the relationship between MR findings and surgery was evaluated. The accuracy of MR imaging for detection of small bowel strictures was defined by a sensitivity of 60.6% and a specificity of 93.4%. Major strictures (diameter less than 10mm or with internal fistula), long strictures (length 10mm or greater), and prestenotic dilatation were predictors of stricture detection by MR imaging (P=0.001, 0.017, and 0.002 respectively). Surgery was performed in 31.6% of patients (18 of 57) in the MR-positive-BAE-positive stricture group and in 10.8% of patients (4 of 37) in the MR-negative-BAE-positive stricture group. Multiple regression analysis showed MR-positive-BAE-positive strictures were an independent risk factor for surgery (P=0.002 at 6months and P<0.001 at 1year). The surgery-free rate in the MR-negative-BAE-positive stricture group was significantly lower than that in nonstricture group at 1year (P=0.001). The specificity of MR imaging for detection of small bowel strictures was clinically sufficient, and the MR procedure could detect critical strictures, which was a predictive factor for surgery. But MR-negative-BAE-positive strictures were also associated with an increased risk compared with no strictures after 1year of follow-up.