Magnetic resonance imaging-based ileal motility quantification predicts stricture response to biologic therapy in...

Small bowel strictures are a common and challenging complication of Crohn's disease (CD), and predicting their responsiveness to medical therapy remains an unmet clinical need.

Strictures, defined by the CONSTRICT consensus as a localized segment demonstrating luminal narrowing and bowel wall thickening, accompanied by pre-stenotic dilation, are a common feature of CD, impairing bowel function, complicating treatment, and often leading to surgery. Predicting which lesions are responsive to medical therapy and which will become obstructive represents an important clinical goal. We aim to characterize ileal strictures in patients with CD by exploring the bowel wall motility in patients receiving biologic agents and evaluating motility's potential role in predicting therapeutic response compared with standard MRE biomarkers.

This retrospective study included subjects between 10-28 years of age with stricturing CD receiving immunotherapy who underwent modification or escalation of biologic therapy and clinically indicated magnetic resonance enterography within a 2-month window. All included patients had ileal strictures identified on magnetic resonance enterography (MRE) based on CONSTRICT criteria. Demographic and clinical variables of the overall cohort were obtained. Clinical response and disease activity were evaluated up to 6 months after therapy initiation or adjustment. Subjects were categorized as "non-responders" if they experienced worsening disease activity, required discontinuation of therapy, or needed surgical intervention. Simplified MR indexes of activity (sMaRIA) assessed the ileum, and motility data were processed using GIQuant® (Motilent Ltd., London, UK) software. Stricture length, volume, wall thickness, and T2 signal intensity were also measured using Motilent® software tools. Statistical analyses included t-tests or Mann-Whitney U tests for continuous variables, chi-square or Fisher's exact tests for categorical variables, and ROC curve analysis to evaluate the diagnostic performance of motility and sMaRIA metrics in predicting treatment response. Significance was set at p<0.05.

A total of 40 subjects (52.54% [n=21] female; mean age 19.77±5.13) were included, with 15 (37.5%) classified as non-responders. No significant differences were observed in age (P=0.60), sex (P=0.94), stricture length (P=0.64), wall thickness (P=0.34), stricture volume (P=0.42), or T2-weighted signal intensity (P=0.31). However, mean motility (176.03±128.63 vs. 67.83±33.88; P=0.006) and its standard deviation (72.06±55.55 vs. 30.27±25.79; P=0.02) were significantly higher in responders. sMaRIA scores were not significantly different between groups (mean 2.75 vs. 3.13; P=0.36). Motility outperformed sMaRIA (AUC 0.812 vs. 0.613; P=0.07) in predicting responses.

Quantitative MRI motility assessment was superior to traditional MRI biomarkers in predicting response to biologic therapy in adolescents and young adults with stricturing CD.