Interobserver and Intermodality Agreement for Detection of Small Bowel Crohn's Disease with MR enterography and CT enterography

Background: Magnetic resonance enterography (MRE) and computed tomography enterography (CTE) visualizes small bowel Crohn's disease (CD) and its complications with high accuracy. The aim of this study was to determine the interobserver and intermodality agreement for detection of small bowel CD. Methods: Fifty patients with suspected or known CD were included in the study and all patients underwent MRE and CTE on the same day. Four radiologists with experience in MRE and CTE techniques participated. Observers were blind to patient histories, results of ileocolonoscopies, and other small bowel examinations. Readers assessed the image quality, the presence of small bowel CD, and seven findings consistent with CD. Results: The image quality was better with CTE than MRE (P < 0.001) but the diagnostic yields were comparable (P = 0.4). For detection of small bowel CD, the interobserver agreement was substantial in CTE (kappa = 0.64) and moderate in MRE (kappa = 0.48). The intermodality agreement was fair to substantial (kappa = 0.40-0.64) for different observers. Two abscesses were detected and confirmed at subsequent surgery. One abscess was not detected with MRE and only recorded by two observers in CTE. A total of 10 fistulas were detected: three were confirmed at subsequent surgery and four were false-positive findings. Conclusions: MRE and CTE have comparable diagnostic yields in patients with suspected or known CD. However, CTE provides better image quality and interobserver agreement. In a substantial number of patients the diagnosis of small bowel CD is observer- and modality-dependent. (Inflamm Bowel Dis 2011; 17: 1081-1088)