P0340Non-Invasive Precision Assessment in Ulcerative Colitis: A Prospective Head-to-Head Comparison of MUC and IBUS-SAS Against Endoscopic Activity

Abstract Background Intestinal ultrasound (IUS) is a validated, non-invasive modality for assessing disease activity in ulcerative colitis (UC). Comparative data on existing IUS activity scores remain limited. This study aimed to evaluate the correlation of two IUS scores—the Milan Ultrasound Criteria (MUC) and the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS)—with endoscopic disease activity. Methods This prospective observational study included adults with confirmed UC who underwent IUS and complete or partial colonoscopy within ±5 days. Endoscopic activity was defined as an endoscopic Mayo score (EMS) 0. The most affected bowel segment was assessed for bowel wall thickness (BWT), color Doppler signal (CDS), bowel wall stratification (BWS), and inflammatory fat (i-fat). MUC and IBUS-SAS scores were calculated. Clinical activity (partial Mayo score) and CRP were also recorded. Correlations were evaluated using Spearman’s rho and diagnostic accuracy via ROC analysis. Results Fifty-two patients were included (67.3% male; median age 37.5 years, IQR 21.5–54). Disease extent was E2 in 31 and E3 in 21 patients. Median partial Mayo score was 5 (IQR 2–7) and median CRP was 8.3 mg/L (IQR 4.4–16.8). Endoscopic activity was present in 45 patients (EMS 1: n = 4; EMS 2: n = 24; EMS 3: n = 15). Median BWT was 5.1 mm (IQR 4.2–5.5), median MUC was 9 (IQR 5.88–9.63), and median IBUS-SAS was 30.9 (IQR 16.4–52.6). BWT 3 mm was strongly associated with endoscopic activity (p 0.001; sensitivity 91.1%, specificity 85.7%). Strong correlations were observed between EMS and BWT (ρ = 0.755), EMS and CDS (ρ = 0.756), and moderate correlations with BWS (ρ = 0.631) and i-fat (ρ = 0.572), all p 0.001. Both IUS scores correlated strongly with EMS (MUC: ρ = 0.757; IBUS-SAS: ρ = 0.789; p 0.001). Diagnostic accuracy was excellent (AUC: MUC 0.985; IBUS-SAS 0.982). Optimal cut-offs for detecting endoscopic activity were 4.48 for MUC (sensitivity 94.1%, specificity 86.7%) and 14.4 for IBUS-SAS (sensitivity 94.3%, specificity 85.7%). Conclusion Both the MUC and IBUS-SAS demonstrated strong correlation with endoscopic activity in UC. Among individual ultrasound parameters, bowel wall thickness and Doppler signal showed the highest association with the endoscopic Mayo score, supporting the role of IUS scoring systems as reliable tools for non-invasive disease assessment. Conflict of interest: Mrs. Vlachou, Evangelia: No conflict of interest