Clinical usefulness of hypoxia imaging colonoscopy for the objective measurement of ulcerative colitis disease activity

Background and Aims: Colonic mucosal hypoxia is associated with mucosal inflammation in ulcerative colitis (UC). We aimed to assess the clinical usefulness of hypoxia imaging colonoscopy for the evaluation of clinical, endoscopic, and histologic disease activities of UC. Methods: This retrospective cohort study comprised 100 consecutive patients with UC who underwent hypoxia imaging colonoscopy between September 2022 and September 2023 at the University of Tsukuba Hospital. Colonic tissue oxygen saturation (StO(2)) was measured at the biopsy sites, and StO(2) values between different disease activities were compared. Receiver-operating characteristic (ROC) analysis was used to calculate the area under the ROC curve (AUROC). Results: A significant correlation was identified between rectal StO(2) and the Simple Clinical Colitis Activity Index, with moderate accuracy to predict bowel urgency at a 40.5% cutoff (AUROC, .74; 95% confidence interval [CI], .62-.87). Our analysis of 490 images showed median StO(2) values for Mayo endoscopic subscores 0, 1, 2, and 3 as 52% (interquartile range [IQR], 48%-56%), 47% (IQR, 43%-52%), 42% (IQR, 38.8%-47%), and 39.5% (IQR, 37.3%-41.8%), respectively. Differences for all pairs were significant. Median StO(2) was 49% (IQR, 44%-54%) for Geboes scores 0 to 2, significantly higher than histologically active disease (Geboes score >= 3). At a colonic StO(2) cutoff of 45.5%, AUROCs for endoscopically and histologically active diseases were .79 (95% CI, .74-.84) and .72 (95% CI, .66-.77). Conclusions: StO(2) obtained by hypoxia imaging colonoscopy is useful for assessing clinical, endoscopic, and histologic activities of UC, suggesting that StO(2) may be a novel and objective endoscopic measurement.