Comparative Accuracy of Bowel Ultrasound Versus Magnetic Resonance Enterography in Combination With Colonoscopy in Assessing Crohn's Disease and Guiding Clinical Decision-making

Background: The comparative accuracy of bowel ultrasound [US] versus magnetic resonance enterography [MRE] in combination with colonoscopy [CS] in assessing Crohn's disease [CD] and influencing the decision-making process is unknown. Methods: Consecutive ileo-colonic CD patients seen in a tertiary referral centre were prospectively assessed by MRE, CS, and bowel US, within 1 week. Sensitivity, specificity, accuracy, positive predictive value [PPV], and negative predictive value [NPV] of bowel US in assessing localisation, enhancement [presence of vascularisation at Power Doppler], active disease [presence of ulcers at colonoscopy], strictures, fistulas, and abscesses were calculated using CS + MRE findings together as a reference standard. Two blinded inflammatory bowel disease [IBD] specialists reviewed MRE and bowel US findings and were asked to decide the therapeutic strategy [continue versus change therapy]. Kappa agreement with clinical decision was calculated. Results: Sixty CD patients [36 with endoscopic disease activity, 28 with complications] were enrolled. For localisation, sensitivity, specificity, accuracy, PPV, and NPV of bowel US were 88%, 96%, 91%, 96%, and 85%, respectively; for enhancement, 87%, 92%, 89%, 93%, and 86%; for activity, 92%, 100%, 96%, 100%, and 94%; for strictures, 75%, 86%, 81%, 78%, and 83%; for fistulas, 100%, 98%, 98%, 66%, and 100%; for abscesses, 100%, 96%, 96%, 33%, and 100%. The concordance of management of CD patients based on bowel US or MRE findings, alone, compared with clinical decision, was 0.768 and 0.767, respectively [p <0.001]. The concordance between bowel US and MRE on management of CD patients was 0.800 [p <0.001]. Conclusions: Bowel US is very accurate in assessing CD and is a non-invasive, easy-to-use tool to manage CD patients in clinical practice.