Bowel Wall Visualization Using MR Enterography in Relationship to Bowel Lumen Contents and Patient Demographics. Issue 3 (4th March 2021) - Zhang, Ting Ting
Abstract : Background: MR enterography (MRE) is generally performed without bowel preparation, but the frequency and extent by which bowel contents affect bowel wall visualization are poorly described in the literature. Purpose: To evaluate MRE bowel wall visualization quality relative to bowel lumen contents and patient demographics. Study Type: Retrospective, single‐center. Population: One hundred and four consecutive patients (mean age 29 years, range 5–76 years) without prior bowel resection who had undergone MRE. Field Strength/Sequence: 3 T ( N = 87) or 1.5 T ( N = 17)/T2‐weighted single‐shot spin echo (T2WI) and fat‐saturated T1‐weighted gradient echo (T1WI) without and with gadolinium. Assessment: For the proximal and distal jejunum and ileum and colon, three readers independently categorized bowel lumen signal (water = bright T2 dark T1, T1‐bright, or air = dark T2 and T1 signal) and scored distension (0 = poor, 1 = moderate, 2 = well) and wall enhancement (0 = unclear, 1 = perceptible, 2 = clear) based upon gadolinium enhanced T1WI for the 104 MRE exams). The bowel visualization score was the sum of the wall enhancement and distension scores and was considered adequate if ≥3. Statistical Tests: Wilcoxon signed‐rank test. Results: The bowel lumen content was water signal in 93% (97/104 scans), 92% (95/104), 98% (102/104), and 93% (92/104) of the proximal and distal jejunum and proximal and distal ileum, respectively, but only in 12.5% (13/104) of the colon. There was adequate bowel visualization of 53.8%, 77.8%, 84.6%, 90.4% of the proximal and distal jejunum and proximal and distal ileum, respectively, but only 19.2% of the colon. In children (age < 18 years), the visualization score of the ileum was lower when the adjacent colon contained air (2.4 ± 0.97) compared to water (3.75 ± 0.29, P < 0.05) or T1‐bright material (3.21 ± 0.82, P < 0.05). Data Conclusion: Without bowel preparation, colon wall visualization was often unsatisfactory at MRE, and air‐filled colon also degraded small bowel visualization, particularly in children. Level of Evidence: 4 Technical Efficacy: Stage 1