Evaluation of noncontrast MR enterography for pediatric inflammatory bowel disease assessment

Background: Gadolinium deposition in normal tissues is being increasingly recognized. Children with inflammatory bowel disease (IBD) undergo frequent imaging with contrast-enhanced MR enterography (MRE). Purpose: To determine the impact of intravenous (IV) gadolinium in assessment of pediatric IBD by MRE. Study Type: Retrospective, case series. Population: Radiology information system was searched to identify all children who underwent MRE and endoscopy within 30 days in 2016. Field Strength/Sequence: 1.5T and 3T. Assessment: Imaging studies were evaluated for bowel inflammation interpreted by two blinded radiologists in two sessions 6 weeks apart (session 1 pre-MRE; session 2 pre/postcontrast-MRE). Endoscopic histology was the reference standard. Statistical Tests: A logistic regression model was evaluated using receiver operating characteristics curves and expressed by c-statistics. Agreement between readers was evaluated using Cohen's or weighted kappa statistic, as appropriate. Two-sided P < 0.05 was considered statistically significant. Descriptive statistics were used for assessment of IBD complications. Results: In all, 52 children (46% female), mean age 13.2 (SD 3.42) years formed the study cohort. 77% (40/52) had inflammation on endoscopic biopsy. Pre/post-MRE showed no significant increase in the c-statistic compared to pre-MRE for assessment of small bowel (Reader 1 P = 0.56, Reader 2 P = 1.00) or large bowel inflammation (Reader 1 P = 0.42, Reader 2 P = 1.00)). Intravenous contrast showed no improvement in interobserver agreement for assessment of inflammation in small (kappa 0.92 pre-MRE, 0.88 pre/post-MRE) or large bowel (kappa 0.83 pre-MRE, 0.73 pre/post-MRE). IV contrast had no meaningful impact on interobserver agreement for length of small bowel inflamed (intraclass correlation coefficient 0.90 pre-MRE, 0.95 pre/post-MRE). Assessment of IBD complications was improved with IV contrast, with 3/5 cases with perianal penetrating disease not recognized on pre-MRE. Data Conclusion: Routine administration of IV gadolinium has no impact on the assessment of bowel inflammation. However, there is potential for missing perianal complications using a noncontrast MRE protocol without dedicated pelvic imaging. Level of Evidence: 3. Technical Efficacy: Stage 2. J. MAGN. RESON. IMAGING 2018;48:341–348.