Accuracy of Diffusion-weighted Magnetic Resonance Colonography in Assessing Mucosal Healing and the Treatment Response in Patients with Ulcerative Colitis

{Background and Aims: Using sigmoidoscopy as the gold standard, we assessed the accuracy, and the responsiveness to change, of diffusion-weighted magnetic resonance colonography in ulcerative colitis, using the Nancy score. Methods: A total of 29 ulcerative colitis patients, having undergone at least two diffusion-weighted magnetic resonance colonographies, were included. Disease activity was evaluated using the Mayo endoscopic subscore and the Nancy score. We determined the accuracy of the Nancy score in the diagnosis of mucosal healing. We also assessed its responsiveness to change in 17 patients with a Mayo endoscopic subscore of 2 or 3 at treatment initiation. Results: A total Nancy score < 7 had a sensitivity of 0.75 and a specificity of 0.67 (area under the curve: 0.72; 95% confidence interval: [0.56-0.88]; p = 0.0063) in the diagnosis of mucosal healing. The total Nancy score was sensitive to change in ulcerative colitis [Guyatt's responsiveness index: 1.8; standardised effect size ratio: 1.36]. The Nancy score was reliable [intra-class correlation coefficient: 0.63; p = 0.01]. The mean Mayo endoscopic subscore and the mean Nancy score both fell significantly in patients who achieved mucosal healing (mean +/- standard deviation [SD] Mayo endoscopic subscore: 2.4 +/- 0.55 at baseline and 0.6 +/- 0.55 at reassessment