Evaluation of Super-Resolution Contrast-enhanced US in Crohn Disease Activity Assessment

Background Measurement of Crohn disease (CD) activity is crucial for guiding treatment decisions. Super-resolution contrast-enhanced US (SRCEUS) is an emerging technique that can be used to assess vascularity at micrometer scale; however, its performance in differentiating CD activity stages is not yet known. Purpose To evaluate SRCEUS in the assessment of disease activity in participants with CD. Materials and Methods This prospective study included participants with CD involving the terminal ileum or colon who underwent intestinal SRCEUS imaging between January 2025 and June 2025. Participants were classified into remission/mild or moderate/severe activity groups based on the Simple Endoscopic Score for Crohn's Disease. B-mode US, color Doppler flow imaging (CDFI), conventional contrast-enhanced US (CEUS), and SRCEUS were performed. SRCEUS parameters were calculated. Logistic regression modeling, receiver operating characteristic analysis, and the DeLong test were used to evaluate and compare diagnostic performance. Results This study included 54 participants (mean age, 30 years ± 8.5 [SD]; 42 men). Key SRCEUS vascular parameters were higher in the moderate/severe activity group than the remission/mild activity group, including maximum density (mean, 63.4 ± 13.1 vs 51.1 ± 15.6; P = .003), mean density (mean, 26.9 ± 5.3 vs 21.1 ± 8.0; P = .007), mean velocity (mean, 40.2 mm/sec ± 27.3 vs 23.0 mm/sec ± 14.9; P = .01), vascular density ratio (mean, 73.2% ± 12.8 vs 38.5% ± 17.8; P < .001), and fractal dimension (mean, 1.7 ± 0.1 vs 1.5 ± 0.1; P < .001). SRCEUS performed well in distinguishing participants with remission/mild activity from those with moderate/severe activity (area under the receiver operating characteristic curve [AUC], 0.92; sensitivity, 94.1%; specificity, 95.0%). SRCEUS performed better than conventional CEUS (AUC, 0.78; P = .03). Clinical, B-mode US, CEUS, and SRCEUS parameters were included in a combined model, in which the International Bowel Ultrasound Segmental Activity Score and vascular density ratio were identified as influential factors. The combined model had an AUC of 0.94, demonstrating superior performance to both CDFI (AUC, 0.82; P = .04) and conventional CEUS (P = .002) and similar performance to SRCEUS (P = .51). Conclusion SRCEUS demonstrated excellent performance in differentiating CD activity through high-resolution depiction of microstructural changes, with superior performance to conventional CEUS. © RSNA, 2026 Supplemental material is available for this article. See also the editorial by Katwal and Chernyak in this issue.