Improvement in small-bowel and colonic lesions observed by intestinal ultrasonography in Crohn's disease treated with risankizumab.

This retrospective, single-center cohort study aimed to investigate improvements in small-bowel and colonic lesions, as assessed by intestinal ultrasonography (IUS), in patients with Crohn's disease (CD) treated with risankizumab. All patients with CD who received risankizumab between February 2023 and August 2024 in a clinic in Japan were included, but those with a prior intestinal resection or normal bowel wall thickness (BWT) on IUS were excluded. For each patient, the segment with the greatest BWT served as the representative lesion. Temporal changes in IUS parameters, including BWT, bowel wall stratification, and superb microvascular imaging, were evaluated at baseline and at weeks 4, 8, 12, 20, and 28. The IUS parameters were then compared between patients grouped according to lesion location (colon, small bowel, terminal ileum, and proximal to the terminal ileum). In total, 33 patients with CD were included. The representative lesion was located in the small bowel and colon in 19 and 14 patients, respectively. Following risankizumab treatment, both the BWT and the BWT reduction rate significantly reduced over time. At week 28, the IUS response rate was 39.4%, while the BWT normalization rate was 24.2%. Additionally, the proportions of patients with superb microvascular imaging grades 0 and ≤1 increased significantly over time, reaching 66.7% and 93.9%, respectively. In terms of lesion location, both the BWT and BWT reduction rate greatly reduced in the colon group compared with those in the small-bowel group (-21.4% vs -17.1%). They also significantly reduced from week 20 onward in the proximal-to-terminal-ileum group. Therefore, risankizumab significantly improved the BWT and vascularity in patients with CD, even in small-bowel lesions proximal to the terminal ileum.