Accuracy of abdominal ultrasound and MRI for detection of Crohn disease and ulcerative colitis in children.

BACKGROUND: Endoscopy is currently the primary diagnostic technique for inflammatory bowel disease (IBD) in children.

OBJECTIVE: To assess the accuracy of US and dynamic contrast-enhanced MRI for diagnosing inflammatory bowel disease and for distinguishing Crohn disease and ulcerative colitis in comparison to a reference standard.

MATERIALS AND METHODS: Consecutive children with suspected IBD underwent diagnostic workup including ileocolonoscopy and upper gastrointestinal endoscopy as the reference standard, abdominal US, and MR enterography and colonography at 3 T. The protocol included a dynamic contrast-enhanced 3-D sequence. Sensitivity, specificity and kappa values were calculated for one ultrasonographer and two MRI observers.

RESULTS: We included 28 children (15 boys) with mean age 14 years (range 10-17 years). The diagnosis was IBD in 23 children (72%), including 12 with Crohn disease, 10 with ulcerative colitis and 1 with indeterminate colitis. For the diagnosis of inflammatory bowel disease the sensitivity was 55% for US and 57% (both observers) for MR entero- and colonography, and the specificity was 100% for US and 100% (observer 1) and 75% (observer 2) for MR entero- and colonography. Combined MRI and US had sensitivity and specificity of 70% and 100% (observer 1) and 74% and 80% (observer 2), respectively. With the addition of a dynamic contrast-enhanced MR sequence, the sensitivity increased to 83% and 87%. US and MRI could only distinguish between Crohn disease and ulcerative colitis when terminal ileum lesions were present.

CONCLUSION: US and MR entero- and colonography have a high accuracy for diagnosing inflammatory bowel disease in children but cannot be used to distinguish Crohn disease and ulcerative colitis.