Seeing Beyond the Surface: Superior performance of Ultrasound elastography over Milan ultrasound criteria in distinguishing fibrosis of ulcerative colitis

Abstract Background Colonic fibrosis has important clinical implications in ulcerative colitis [UC]. Ultrasound imaging has emerged as a convenient and reliable tool in diagnosis of inflammatory bowel disease. We aimed to explore the potential use of ultrasound to evaluate UC fibrosis. Methods Consecutive UC patients who had proctocolectomy from July 2022 to September 2023 were enrolled in the study. Patients underwent bowel ultrasound examination and ultrasound elastography imaging prior to surgery. Milan ultrasound criteria [MUC] were calculated and bowel wall stiffness was determined using two mean strain ratios [MSRs]. Degree of colonic fibrosis and inflammation was measured upon histological analysis. Receiver operating characteristic [ROC] analysis was used to evaluate the performance of ultrasound-derived parameters to predict fibrosis. Results In all, 56 patients were enrolled with 112 segments included in analysis. The median fibrosis score was 2 [0-4] and the median Geboes score was 5 [0-13] and these two scores were significantly correlated [p < 0.001]. The muscularis mucosa thickness was significantly higher in moderate-severe fibrosis than none-mild fibrosis [p = 0.003] but bowel wall thickness was not [p = 0.082]. The strain ratios [p < 0.001] and MUC [p = 0.010] were significantly higher in involved than non-involved segments. The strain ratios were correlated with fibrosis score [p < 0.001] but not MUC [p = 0.387]. At ROC analysis, mean strain ratio 1 [MSR1] had an area under the curve [AUC] of 0.828 [cutoff value 3.07, 95% CI 0.746-0.893, p < 0.001] to predict moderate-severe fibrosis. Conclusion Ultrasound elastography imaging could predict the degree of colonic fibrosis in UC. Application of this technique could help disease monitoring and decision making in UC patients.