Prospective Comparison of State-of-the-Art MR Enterography and CT Enterography in Small-Bowel Crohn's Disease

OBJECTIVE. The objective of our study was to prospectively obtain pilot data on the accuracy of MR enterography for detecting small-bowel Crohn's disease compared with CT enterography and with a clinical reference standard based on imaging, clinical information, and ileocolonoscopy. SUBJECTS AND METHODS. The study group for this blinded prospective study was composed of 33 patients with suspected active Crohn's ileal inflammation who were scheduled for clinical CT enterography and ileocolonoscopy and had consented to also undergo MR enterography. The MR enterography and CT enterography examinations were each interpreted by two radiologists with disagreements resolved by consensus. The reports from ileocolonoscopy with or without mucosal biopsy were interpreted by a gastroenterologist. The reference standard for the presence of small-bowel Crohn's disease was based on the final clinical diagnosis by the referring gastroenterologist after reviewing all of the available information. RESULTS. All 33 patients underwent CT enterography and ileocolonoscopy, 30 of whom also underwent MR enterography. The sensitivities of MR enterography and CT enterography for detecting active small-bowel Crohn's disease were similar (90.5% vs 95.2%, respectively; p = 0.32). The image quality scores for MR enterography examinations were significantly lower than those for CT enterography (p = 0.005). MR enterography and CT enterography identified eight cases (24%) with a final diagnosis of active small-bowel inflammation in which the ileal mucosa appeared normal at ileocolonoscopy. Furthermore, enterography provided the only available imaging in three additional patients who did not have ileal intubation. CONCLUSION. MR enterography and CT enterography have similar sensitivities for detecting active small-bowel inflammation, but image quality across the study cohort was better with CT. Cross-sectional enterography provides complementary information to ileocolonoscopy.