Intestinal ultrasound versus magnetic resonance enterography for detecting small bowel Crohn's disease in children

OBJECTIVES: In Crohn's disease (CD), magnetic resonance enterography (MRE) is used to assess small bowel disease activity. Intestinal ultrasound (IUS) is a less invasive, cheaper and more easily accessible imaging modality in CD. This study assesses the diagnostic accuracy of IUS versus MRE and defines an optimal bowel wall thickness (BWT) cut-off in children. METHODS: Children with CD undergoing MRE as routine care had IUS within 7 days. MRE disease activity was assessed using the segmental grading system and compared to IUS BWT and IUS scores. The terminal ileum (TI), ileum and jejunum were analysed separately. RESULTS: Seventy-eight paediatric CD patients (median age: 15 years; 49% female) were included. Based on MRE, 44 bowel segments had mild and 37 moderate-severe disease activity. The area under the receiver operating characteristic of IUS BWT for disease activity in the TI was 0.91 (95% confidence interval [CI] 0.84-0.98) with an optimal cut-off of 2.4 mm, 0.80 (95% CI 0.66-0.94) for the ileum with an optimal cut-off of 2.0 mm (sensitivity 76%; specificity 93%) and 0.69 (95% CI 0.52-0.86) for the jejunum. Due to the low number of affected segments in the jejunum, an accurate BWT cut-off value could not be determined. Previously developed IUS scores did not outperform BWT. CONCLUSIONS: IUS is an accurate tool to non-invasively assess CD activity in the TI and ileum. Based on our results, a BWT cut-off of 2.4 mm in the TI and 2.0 mm in the ileum in paediatric CD is optimal to distinguish active from inactive disease.