MR enterography offers a potentially attractive, radiation-free alternative to CT imaging of children with inflammatory bowel disease (IBD), Crohn's disease and chronic ulcerative colitis. The exam is feasible in patients nine years old and older, according to an assessment of its image quality, patient tolerance and performance published in the September issue of American Journal of Roentgenology.
IBD, Crohn's disease and chronic ulcerative colitis affect 1.4 million U.S. residents and 2.2 million Europeans, and pediatric incidence has risen. As cross-sectional imaging is used to answer diagnostic questions and inform therapy, children with these conditions are increasingly exposed to radiation.
“[Because] young patients with IBD may already be at increased risk for malignancy related to chronic intestinal inflammation and/or immunotherapeutic agents, there exists a need to develop noninvasive, nonionizing, and well-tolerated imaging modalities for pediatric patients with IBD,” wrote Imad Absah, MD, from the division of pediatric gastroenterology at Mayo Clinic College of Medicine in Rochester, Minn. However, pediatric patients present challenges including poor acceptance of oral contrast, inadequate breath-hold compliance and increased motion.
Mayo Clinic increased its use of MR enterography from two studies in late 2007 to 10 in 2008, 34 in 2009 and 39 between January and July 2010.
Absah and colleagues conducted a retrospective study to evaluate image quality, oral contrast administration and bowel distension, side effects and performance estimates of the exam among pediatric patients with IBD.
The study included 85 exams in 70 patients. Two gastrointestinal radiologists rated image quality, including artifacts and overall quality, of the exams on a five-point scale, with a score of five corresponding with excellent image quality.
Researchers also determined bowel distension with contrast administration for each patient and reviewed side effects. The exams were reviewed to assess active IBD and disease activity. MR enterography reports were compared with ileocolonoscopy results when available to derive performance estimates.
The study population included 38 patients with Crohn's disease, 23 patients with chronic ulcerative colitis, and indeterminate colitis in two patients. Mean patient age was 15.6 years.
Absah and colleagues reported artifact scores generally indicated mild artifacts not affecting diagnostic confidence. “The mean image quality score for unenhanced pulse sequences was 4.7 and significantly greater than gadolinium-enhanced sequences at 4.1.” Thus, in most cases, results were acceptable.
Six exams were limited by poor bowel distension. A total of 61 patients ingested >450 mL of contrast, with age acting as a significant independent predictor of ingested contrast.
Three adverse events were reported, but none required ongoing care.
Forty-eight patients underwent an endoscopic procedure within two weeks of the MR exam. Based on these results, MR enterography delivered sensitivity for active disease of 80 percent for the terminal ileum, 79.1 percent for the right colon and 90.3 percent for the left colon.
“MR enterography is a noninvasive feasible examination without sedation in pediatric patients nine years old and older with IBD. The volume of oral contrast material required for high-quality examinations can be predicted by patient age. MR enterography is a sensitive test in identifying active disease in comparison with colonoscopy,” wrote Absah et al.