Development and Validation of a Magnetic Resonance Index for Assessing Fistulas in Patients With Crohn’s Disease

There is no validated magnetic resonance imaging (MRI) index for assessment of perianal fistulas in patients with Crohn's disease (CD). We developed and internally validated a new instrument.We used paired baseline and week-24 MRI scans from 160 participants in a randomized placebo-controlled trial of stem cell therapy for patients with perianal fistulizing CD. Four radiologists scored disease activity using index items identified during...