Prognostic value of magnetic resonance enterography for children with Crohn's disease: A multicenter, multireader study

Background: Paediatric Inflammatory Crohn's MRE Index (PICMI) is a multi-point index of intestinal inflammation (mucosal and transmural) for children with CD. The present study aims to assess whether PICMI at diagnosis may predict the course of CD and to test the inter-reader agreement.

Methods: CD children with a ≥ 1-year follow-up were retrospectively enrolled. Three radiologists calculated PICMI at diagnosis and association between PICMI and Paediatric Crohn's Disease Activity Index (PCDAI) and CD Endoscopic Index of Severity (CDEIS) was tested.

Results: 68 children (median age 13 years IQR: 11-14) with CD with PICMI at diagnosis: remission 6 (8.8 %), mild 29 (42.6 %), moderate 24 (35.3 %), severe 9 (13.2 %), were enrolled. PICMI score significantly correlated with PCDAI at diagnosis (p: 0.036). Steroid-free remission at 1, 3 and 5 years was comparable between PICMI groups (p: 0.606). Higher PICMI at diagnosis was associated with higher biologic introduction at 1 year: incidence rate ratio IRR: 2.17 (1.09-4.42); p = 0.019, 3-year IRR: 2.12 (1.15-3.96); p = 0.011, and 5 years: 2.21 (1.20-4.08); p = 0.007.

Conclusions: PICMI score is a reliable and almost reproducible index to score activity in children with CD. Children with higher PICMI scores of disease activity at diagnosis required more biologic treatment to achieve comparable rates of steroid-free remission if compared with lower PICMI scores.