Baseline Magnetic Resonance Enterography Stratifies Persistence Risk of Crohn's Disease Strictures.

BACKGROUND & AIMS: Crohn's disease (CD) strictures are clinically important, but persistence after advanced therapy remains difficult to assess. We developed and temporally validated a magnetic resonance enterography (MRE)-based framework integrating activity-related and structural imaging severity to stratify stricture non-improvement. METHODS: This two-stage study included patients with CD who initiated advanced therapy and underwent baseline and follow-up MRE. An activity-related score (A-score) and a persistence-associated structural score (P-score) were derived in a development cohort (2012-2020) and applied to a temporally separated validation cohort (2021-2024). The primary endpoint was stricture-level non-improvement on follow-up MRE; intestinal surgery was also evaluated. RESULTS: The development cohort included 115 patients with 161 strictures, and the validation cohort included 72 patients with 104 strictures. The A-score comprised bowel wall thickness >6 mm, ulceration, and comb sign; the P-score comprised stricture length >3 cm, prestenotic bowel diameter >3 cm, and lack of intramural edema. A-score and P-score positivity were each associated with stricture non-improvement after multivariable adjustment (adjusted odds ratios, 18.68 and 19.75, respectively; P<.01 for both). The summed A+P score showed an area under the curve of 0.90 and higher discrimination than either score, segmental MaRIA, or segmental sMaRIA alone. Improvement rates decreased with increasing A-scores and remained low at higher P-scores. Baseline A/P strata also differed in surgery-free survival (P<.01). CONCLUSIONS: Baseline MRE integrating activity-related and structural imaging severity stratified stricture persistence and was associated with subsequent surgery. This framework should be interpreted as a baseline imaging severity and risk-stratification tool rather than an inflammatory-fibrotic phenotype classifier.