Update on Novel Biologic Therapies for Crohn Disease and the Impact of Imaging on Clinical Decision Making.

As Crohn disease treatment rapidly evolves, imaging has a critical role in treatment response assessment and clinical decision making. Therapy is often "top down," with the most powerful and potent therapies selected first. Disease activity assessment remains multifactorial, integrating source data from biomarkers, symptoms, endoscopy, and imaging. The "treat-to-target" approach also integrates these markers to escalate, de-escalate, or switch therapies. Given the transmural nature of Crohn disease, endoscopic mucosal healing (ie, the current treatment target) may not be sufficient evidence of remission, and imaging assessment of transmural healing could prove a better predictor of treatment response and long-term patient outcomes. Quantitative imaging methods have been developed to standardize treatment response assessment, including emerging radiologic techniques such as contrast-enhanced US, T1 mapping at MRI, standardized stricture assessment, and velocity-encoded phase contrast imaging. Morphologic changes of resolving inflammation at imaging may lag behind clinical response, and complete normalization of inflamed bowel segments may occur infrequently. In these cases, evaluating changes in bowel motility may be may be more helpful for detection of early treatment response. The radiologist is critical in the assessment of Crohn disease, providing insight into disease management and endoscopically occult and subclinical inflammation. The goal of this article is to highlight the role of imaging in driving management of Crohn disease, including endoscopically occult and subclinical disease, transmural healing, and treatment decision making in patients undergoing biologic therapies. ©RSNA, 2026 See the invited commentary by Srinivasan and Taylor in this issue.