Accuracy of superb microvascular imaging (SMI) in predicting endoscopic Crohn's disease activity.

Background: Treat-to-target therapy in inflammatory bowel disease requires longitudinal assessment of disease activity and intestinal ultrasound (IUS) is a promising non-invasive and cheap technology to provide objective read-outs. Vascularization of the bowel wall is one key parameter on IUS. While this is conventionally done with Color doppler imaging, it is currently unclear whether microvascular flow imaging techniques might improve the diagnostic performance of IUS.

Aims: To explore the utility of superb microvascular imaging (SMI) for assessing disease activity in Crohn's disease (CD).

Methods: We performed a prospective single-center cross-sectional cohort study including 56 patients with CD. IUS was performed on the terminal ileum or sigmoid colon within 30 days of colonoscopy and the International Bowel Ultrasound (IBUS) group Segmental Activity Score (SAS) as well as SMI signals were determined and correlated to established endoscopic, clinical and biochemical read-outs of disease activity.

Results: SMI scores showed superior correlation to endoscopic disease activity than Doppler imaging scores. While this did not further improve the diagnostic performance of the composite IBUS-SAS, SMI scores as a single parameter excellently predicted segmental endoscopic disease activity.

Conclusions: SMI is a highly promising tool to improve or simplify the non-invasive assessment of disease activity in CD that should further be investigated in real-world and multi-center trials.