Background: A simplified magnetic resonance enterography (MRe) index (sMARIA) for Crohn's disease (CD) was recently developed and validated.
Objective: Our aims were (a) to assess sMARIA's accuracy in a sample other than the validation cohort; (b) to evaluate its correlation with a simpler endoscopy index (SES-CD) and fecal calprotectin (FC); and (c) to assess the need of an expert radiologist to reliably use sMARIA.
Methods: Patients with CD who underwent MRe, ileocolonoscopy and FC within 2-4 weeks had their MRe retrospectively reviewed by two blinded raters. Disease activity was evaluated through sMARIA, SES-CD and FC. sMARIA's accuracy, indices correlation, and interrater reliability were assessed.
Results: In total, 84 patients were included, comprising 420 intestinal segments evaluations. sMARIA ≥1 accurately identified segments with active disease (90% sensitivity, 98% specificity; area under the curve 0.94, 95% confidence interval (CI) 0.91-0.97; p < 0.01). sMARIA correlated with endoscopy, both for ileal and colonic segments (R = 0.94 and R = 0.82; p < 0.01). Per patient, there was a strong correlation between sMARIA, endoscopy (R = 0.95; p < 0.01) and FC (R = 0.91; p < 0.01). Interrater agreement was excellent (intraclass correlation coefficient 0.95; 95% CI 0.94-0.96; p < 0.01).
Conclusion: sMARIA accurately measured CD activity using SES-CD as standard of reference, and exhibited high correlation with a simple endoscopic index and a biomarker. The interrater reliability between a radiology resident and an expert was excellent.
Keywords: Inflammatory Bowel Disease; Magnetic Resonance; monitoring tools.