Discordance between MR enterography and endoscopic detection of Crohn's disease ileal strictures: evidence to inform recommendations

Purpose: To evaluate correlation between terminal ileal (TI) stricture diagnosis at MR enterography (MRE) and ileocolonoscopy (IC) in patients with Crohn's disease (CD).

Methods: One hundred and four patients with CD (51% females; 41 ± 15 years) underwent IC and MRE within 3 months in this retrospective case-control study. Positive cases had TI strictures diagnosed by endoscopy (n = 35); or MRE (threshold small bowel dilation ≥ 3cm; n = 34). Negative controls did not have stricture by either modality (n = 35). Three radiologists examined MRE exams, with per-patient stricture diagnosis based on majority agreement. Sensitivity for stricture diagnosis using threshold dilation of 2.5 cm at MRE was also evaluated.

Results: There were 69 CD TI strictures (57 by endoscopy; 43 by MRE). Sensitivity by endoscopy and MRE criteria were 82.6% (57/69) and 62.3% (43/69), respectively, with additional 20.3% (14/69) of MRE exams classified as "probable stricture" by SAR/AGA/SPR criteria. Lowering MRE small bowel dilation threshold to 2.5 cm increased MRE sensitivity for endoscopically-diagnosed strictures to 71.9% (41/57; up from 56.1% [32/57]), without sacrificing interobserver agreement (κ = 0.684 vs. κ = 0.587). Of 25 new patients diagnosed with a TI stricture using a 2.5 cm threshold by 2 or more readers, 96% (24/25) had hospitalization, small bowel obstruction, endoscopic dilation, and/or surgical resection during clinical follow-up. Nine false negative MRE exams had short strictures with bowel dilation ≥ 2.5 cm.

Conclusion: Either IC or MRE alone is insufficient to diagnose Crohn's small bowel strictures. Diagnostic criteria should incorporate endoscopic and MRE findings. Lowering threshold dilation to 2.5 cm increases sensitivity in stricture diagnosis and identifies clinically significant strictures.