MRI Useful in Children With Inflammatory Bowel Disease (2010)

Source: Alexopoulou E, Roma E, Loggitsi D, et al. Magnetic resonance imaging of the small bowel in children with idiopathic inflammatory bowel disease: evaluation of disease activity. Pediatr Radiol. 2009; 39(8): 791– 797; doi: 10.1007/s00247-009-1272-zInvestigators from National and Kapodistrian University of Athens sought to develop a magnetic resonance (MR) imaging protocol for the assessment and follow-up of small bowel abnormalities in children with Crohn disease (CD), without the need for fluoroscopy and bowel intubation, and to analyze its utility for evaluating disease activity.The children included in the study were referred for small bowel MR imaging because of clinical exacerbation of either histologically proven CD or indeterminate colitis. All patients had C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) determinations within one month prior to their MR. The Pediatric Crohn Disease Activity Index (PCDAI) was used to assess clinical activity.To opacify and distend the small bowel on the day of the MR exam, patients drank 2.5 liters of water containing 0.1 grams per kilogram body weight of herbal fibers (psyllium). Hyoscine bromide was given intravenously to decrease bowel peristalsis and prolong small bowel distention. Intravenous gadolinium was used to enhance the imaging of acute inflammation. The images were reviewed by a single experienced radiologist blinded to the clinical and laboratory assessment or results. Images were studied for bowel wall thickening (>3mm), luminal narrowing, and transmural and extraintestinal abnormalities. Pathologic bowel wall enhancement was defined by visual assessment and by quantitative analysis. Bowel stenosis was defined as constant narrowing of an area of bowel lumen with an immediately proximal area of pre-stenotic dilation. Abnormal lymph nodes were defined as the shortest diameter >5 mm in the mesentery or >10 mm in the retroperitoneum.Thirty-seven children were enrolled, of whom 22 were girls; 32 had CD and 5, indeterminate colitis. The ages ranged from 7 to 15 years (mean of 11.7 years). None of the patients required sedation. The findings included pre-stenotic dilation in the terminal ileum (3 patients) and in the mid-transverse colon (1), creeping fat (14), and abnormal mesenteric nodes (13). Neither superficial ulcers nor deep ulcers were identified. Abnormal segments ranged from 2 to 80 cm (mean = 21.2 cm) and wall thicknesses from 2.5 to 12 mm (mean = 5.95 mm). Contrast enhancement findings did not correlate with PCDAI or ESR but enhancement in affected areas was significantly greater among those with abnormal CRP values.The authors conclude that their technique, including the use of psyllium, was well tolerated and allowed imaging satisfactory for assessing CD extent, activity, and extraluminal manifestation without the need for the ionizing radiation of either a small bowel series or CT.This study underscores the usefulness of MR imaging in the assessment of CD. Of course, different institutions have different cultures regarding the evaluation and follow-up of patients with CD. The lack of a cohort of children who underwent routine non-MR imaging such as fluoroscopic contrast studies precludes any comparison of the relative efficacy of each study to detect abnormalities. However, the authors were able to define a protocol that assists in identifying characteristic lesions of CD.Interestingly, the authors confirmed Schunk’s finding that the clinical CD activity index does not correlate with MR findings of inflammation.1 There was, however, good correlation of the radiographic findings with CRP but not to the ESR.The current study along with the work of Siddiki2 and Applegate3 highlight CT and MR’s superiority for assessing disease activity as compared to barium fluoroscopic examinations in patients with CD. This is primarily due to the improvements in spatial and temporal resolution along with the use of better bowel distending agents. An advantage to MR is that it allows for repeated assessments yet avoids the need for radiation. Radiation exposure has been of great concern,5 particularly for young people with a chronic disease. Desmond, et al6 highlighted a subset of CD patients at particular risk for multiple CT exams including those with upper gastrointestinal tract disease, those diagnosed at a younger age, those with penetrating disease and those requiring intravenous corticosteroids, infliximab, or multiple surgeries.The world of cross-sectional imaging, aided by faster computer analysis including that made available by more powerful 2D and 3D software programs, has improved the ability of radiologists to assist with assessments of CD patients. Further refinements with regard to MR speed and techniques will hopefully allow such patients to take advantage of imaging breakthroughs while controlling overall lifetime radiation exposures.