Persisting signs of disease activity at Magnetic Resonance Enterocolonography predict clinical relapse and disease progression in quiescent Crohn's disease

Introduction : Deep remission including clinical remission and tissue healing has been advocated as the therapeutic target in Crohn's disease. Yet, the definition of deep remission remains unclear. The aim of this study was to assess the persisting lesions at magnetic resonance enterocolonography (MREC) in clinically quiescent Crohn's disease as well as their relapse predictive value. Methods : we performed a prospective monocentre cohort study. We included patients with clinical remission. At baseline, these patients had blood tests, the measurement of fecal calprotectin and underwent a MREC. They were then followed up clinically for a minimum of 1 year. A relapse was defined by a HBI > 4 with an increase of at least 3 points. Correlations between clinical, demographic, biological parameters and MREC signs were assessed as well as the time-to-relapse predictive value of the studied variables. Results : Twenty seven patients were recruited. Fourteen out of 27 had persisting disease activity at MREC. MREC signs only partly correlated with biomarkers. Ten out of 27 patients relapsed over a median follow up of 25 months. In univariate analysis, relative contrast enhancement of the most affected segment (HR : 2.56; P = 0.046), ulcers (HR : 12.5; P = 0.039), fistulas (HR : 14.1; P = 0.009) and target sign (HR : 3.63; P = 0.049) were associated with relapse. In multivariate analysis, fistula was the only one. Conclusions : Half of the patients with clinically quiescent Crohn's disease had persisting signs of disease activity at MREC. These signs predicted time-to-relapse.