Background and Aims: A simplified magnetic resonance index of activity (MaRIAs) was proposed recently. Our aim was to verify whether the MaRIAs can accurately assess the activity degree of CD.
Methods: We retrospectively analyzed the data of MRI, ileal colonoscopy, fecal calprotectin (FC), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) of 93 CD patients. With the SES-CD as the gold standard, MaRIAs’ accuracy, The correlation of MaRIAs and SES-CD, FC, ESR, CRP, and interevaluator reliability were assessed.
Results: MaRIAs≥1 detected segments with active CD with 90.80% specificity and 81.37% sensitivity (area under the curve was 0.91, 95% confidence interval 0.87-0.94). MaRIAs score of 2 or more detected severe lesions with 88.89% specificity and 95.12% sensitivity (AUC was 0.96, 95% confidence interval was 0.94-0.98). The MaRIAs score showed a high correlation with the SES-CD in the terminal ileum, transverse colon, right colon, left colon (r=0.85, 0.91, 0.88, 0.86,P < 0.001) and a moderate correlation with the SES-CD in the rectum (r=0.74, P < 0.001). The global MaRIAs score was highly correlated with the global SES-CD (r=0.90, P < 0.001). The global MaRIAs score was positively correlated with the fecal calprotectin (FC) level, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level (r=0.77, r=0.64, and r=0.68). The intra-group correlation coefficient (ICC) of the two physicians in the terminal ileum, right colon, transverse colon,and left colon was 0.91, ICC in the rectum was 0.78, and ICC in the total bowel was 0.95 (95% confidence interval was 0.95-0.98).
Conclusion: The MaRIAs can accurately evaluate the disease activity level of CD, high correlated with the SES-CD and biomarker. The interrater reliability of the two physicians was excellent.