Impact of Small Bowel MRI in Routine Clinical Practice on Staging of Crohn's Disease

Background and Aims: Small bowel visualisation is a complex diagnostic approach, but mandatory for risk stratification and stage-adjusted therapy in Crohn's disease. Current guidelines favour transabdominal ultrasound and small bowel MRI as methods of choice, although their clinical impact in daily practice remains controversial. The aim of this study was to evaluate the diagnostic benefit of small bowel MRI in Crohn’s disease according to Montreal Classification, in routine practice. Methods: Patients who underwent MR-enterography [MRE] or MR-enteroclysis [MRY] were included in a retrospective single-centre study. MRI findings were correlated with results from clinical work-up and evaluated in terms of [1] diagnostic yield, [2] significant additional information, and [3] alterations in the assessment of disease behaviour and location according to Montreal Classification. Results: A total of 347 small bowel MRI examinations were analysed [MRE: 49 / MRY: 298]. MRI had an average sensitivity/specificity of 82.5% and 99.9% [positive predictive value: 99.8% / negative predictive value: 91.1%] respectively. In every second patient, new relevant diagnostic information was provided. Incorporation of the MRI results caused significant shifts in Montreal Classification, specifically higher L-levels [+21.2%; p < 0.05] and higher B-levels: [+24.6%; p < 0.05]. Conclusions: Even in routine practice, small bowel MRI is a powerful and reliable technique in small bowel work-up. Since MRE and MRY presented high diagnostic yields, often detected significant additional information, and significantly caused shifts in Montreal Classification, both techniques are confirmed to be excellent tools in diagnosing and monitoring Crohn’s disease in its daily course.