Imaging endpoints in inflammatory bowel disease: current evidence and future directions for ultrasound and MRI

BACKGROUND: Imaging has become a central and rapidly evolving domain in inflammatory bowel disease (IBD) because it captures disease manifestations that extend beyond the mucosa and, therefore, beyond what can be visualized by endoscopy, including transmural inflammation, extraintestinal complications and small-bowel involvement that are not adequately assessed by conventional approaches. MAIN BODY: In this narrative review, we synthesize the latest evidence on non-invasive cross-sectional imaging-intestinal ultrasound (IUS) and magnetic resonance imaging/enterography (MRI/MRE)-and outline a pragmatic framework for integrating these modalities into clinical trials. The timing of this review reflects the recent publication of two major consensus statements that specifically address how IUS and MRI can be standardized and operationalized as trial endpoints. We first summarize recommended technical standards for acquisition and reporting. We then outline trial-ready definitions of response and remission for clinical trials using validated scores and discuss the emerging but still variably defined construct of transmural healing, understood as the resolution of inflammation across the full thickness of the bowel wall and increasingly associated with improved long-term outcomes. Building on these components, we propose a practical pathway to incorporate imaging from screening, through on-treatment monitoring at predefined windows to adjudicate response/remission, and, where appropriate, to evaluate transmural healing. We emphasize central reading, harmonized timing, and standardized data repositories to minimize bias. CONCLUSION: Even though meaningful steps have been taken to integrate cross-sectional imaging, it remains essential to evaluate its use pragmatically in both trials and routine care. Furthermore, cost-effectiveness analyses are needed to determine whether widespread implementation is economically justified, and studies should examine whether incorporating IUS/MRI improves patient adherence to clinical trial protocols and follow-up compared with traditional assessment pathways.