Abstract
OBJECTIVES: To compare the responsiveness of linear and volumetric assessments of intestinal inflammation in children with newly diagnosed ileal Crohn disease (CD) into treatment. MATERIALS AND METHODS: Twenty children with ileal CD (8 girls; mean age = 14.0 years) between May 2019 and April 2021 underwent research MRI at three time points-diagnosis, 6 weeks, and 6 months into treatment. For each examination, a radiologist measured the maximum wall thickness and length of disease. Then, the inflamed ileum was manually and semi-automatically segmented to measure the tissue volume. Mixed-effects models were used to assess the changes over time. Intra-class correlation was used to assess agreement between manual and semi-automated segmentation. RESULTS: Length of disease decreased with medical treatment (19.2 vs. 12.2 vs. 8.0 cm; p = 0.002), 36% from baseline to 6 weeks and 58% from baseline to 6 months, while maximum bowel wall thickness also decreased over time (7.6 vs. 5.8 vs. 4.5 mm; p < 0.0001), 24% from baseline to 6 weeks and 41% from baseline to 6 months. Manual volumetric measurements demonstrated a significant treatment response (19.8 vs.11.6 vs.5.1 mL; p < 0.0001), 41% decrease from baseline to 6 weeks and 74% from baseline to 6 months. Using semi-automated segmentation, the volume decreased significantly over time as well (24.0 vs.15.1 vs.9.1 mL; p = 0.0007), 37% from baseline to 6 weeks and 62% from baseline to 6 months. There was good agreement between manual and semi-automated volumetric assessments (ICC = 0.78 [95% CI: 0.57-0.88]). CONCLUSION: Volumetric measurement of inflammation is responsive to medical treatment in CD and, as percentage compared to baseline, may show greater treatment response than linear measurements. KEY POINTS: Question Volumetric measurements of intestinal inflammation related to Crohn disease may be superior to traditional linear measurements. Findings Volumetric measurements showed greater treatment response when compared to linear measurements, and there was good agreement between manual and semi-automated volumetric measurements of intestinal inflammation. Clinical relevance Volumetric assessment is a promising tool that may provide a novel biomarker for evaluating intestinal inflammation and treatment response in Crohn Disease.