Different imaging techniques' diagnostic efficacy for Crohn's disease activity and external validation and comparison of MDCTAs, SES-CD and IBUSSAS

Background Crohn's disease (CD) is a chronic inflammatory disease of the digestive tract with unknown etiology. It follows a relapse-remission pattern, making disease activity assessment crucial for treatment. Our study aims to evaluate the diagnostic accuracy of various imaging modalities and to validate and compare the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS), the multidetector computed tomography enterography score (MDCTEs), and the simplified endoscopic activity score for Crohn's disease (SES-CD). Methods We assessed diagnostic performance using the CD Activity Index (CDAI). We first categorized patients into remission and active groups. For those in the active stage, we further categorized them into mild/moderate and severe activity groups. We used Spearman rank correlation to evaluate the relationships among IBUS-SAS, bowel wall thickness (BWT), Color Doppler imaging signal (CDS), inflammatory fat (i-fat), bowel wall stratification (BWS), and clinical inflammatory indicators. Results A total of 103 CD patients were evaluated. The IBUS-SAS cut-off for remission and activity was 23.8, with an AUC of 0.923, sensitivity of 91.4%, and specificity of 84.8%. The SES-CD had an AUC of 0.801, sensitivity of 62.9%, and specificity of 84.4% at a cut-off of 4.5. The MDCTEs showed an AUC of 0.855, sensitivity of 77.1%, and specificity of 75.8% for a cut-off of 6.5. The Delong test revealed significant differences in diagnostic efficacy when comparing IBUS-SAS to SES-CD and IBUS-SAS to MDCTEs. In the group of mild or moderate-to-severe active, the IBUS-SAS had an AUC of 0.925, sensitivity of 83.7%, and specificity of 88.9% at a cut-off of 40. The SES-CD exhibited an AUC of 0.850, sensitivity of 90.7%, and specificity of 70.4% at a cut-off of 8.5. MDCTEs showed an AUC of 0.909, sensitivity of 83.7%, and specificity of 85.2% at a cut-off of 8.5. During Delong test, the IBUS-SAS, MDCTEs, and SES-CD showed no significant differences in assessing moderate-to-severe activity. Both IBUS-SAS and ultrasound parameters correlated with certain serum indicators (p < 0.05), although only weakly to moderately (all r < 0.5). Conclusion The IBUS-SAS, MDCTEs and SES-CD can evaluate disease remission/active and mild/moderate-to-severe active in CD, and IBUS-SAS offers the potential to precisely define CD activity.