A comparative study to assess the diagnostic value of transabdominal ultrasound and magnetic resonance imaging in patients with inflammatory bowel diseases

Background: lleocolonoscopy still represents the diagnostic gold standard in the work-up of patients with inflammatory bowel diseases (IBD). Because of the necessity to clean the colon extensively and the invasive and often painful procedure, patients are often reluctant to be colonoscoped. The purpose of this study was to evaluate the usefulness of transabdominal ultrasound (US) and magnetic resonance imaging (MR1) to assess disease extension and seventy of the terminal ileum and colon in patients with IBD. Methods: Seventy consecutive patients with confirmed IBD (43 with Crohu's disease and 27 with ulcerative colitis) were included. Patients underwent clinical assessment, laboratory testing, ileocolonoscopy, US, and MRI within 5 consecutive days. Involved bowel segments were defined as those with bowel wall thickness > 3 mm assuming an increased Doppler signal on US or moderate contrast enhancement of the bowel wall on MRI. Endoscopy served as diagnostic gold standard. Severity of disease was graded wath newly developed scores for endoscopic, MRI, and US findings. Results: A segment-by-segment analysis revealed an overall accuracy of 89% for US and 73% for MRI in identifying active IBD lesions. The accuracy was higher in patients with ulcerative colitis (UC) compared to patients with Crohn's disease (CD) for both US and MRI (95% vs. 85% and 81% vs. 67%, respectively). The US activity index showed a strong correlation with the endoscopic activity index (EAI) (r = 0.884, p < 0.0009), whereas the MRI activity index did not correlate with the EA1 (r = 0.344, p = 0.007). Correlation of EAI with US and MRI activity index was better in patients with UC (r = 0.974, p = 0.0009 and r = 0.519, p = 0.009, respectively) than in patients with CD (r = 0.830, p < 0.0009 and r = 0.120, p = 0.482, respective). The extension and severity of inflammation as assessed on US and MRI varied according to location of affected bowel segment. All three imaging methods showed a significant correlation with clinical disease activity index in patients with UC but not in patients with CD. In addition, EA1 and US activity index showed a significant correlation with C-reactive protein in patients with UC. Conclusion: Trausabdominal ultrasound provides a reliable, cheap and safe tool to assess disease extension and activity in patients vath IBD and should be considered as a first-choice method for the follow up of patients with confirmed diagnosis of IBD.