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 assessment of clinical, endoscopic, and histologic disease activities of UC. METHODS:This was a retrospective cohort study comprised of 100 consecutive UC patients who underwent hypoxia imaging colonoscopy between September 2022 and September 2023 at the University of Tsukuba Hospital. We measured colonic tissue oxygen saturation (StO2) at the biopsy sites and compared StO2 values between different disease activities. We used receiver operating characteristic (ROC) analysis to calculate the area under the ROC curve (AUROC). RESULTS:We identified a significant correlation between rectal StO2 and the Simple Clinical Colitis Activity Index, with moderate accuracy to predict bowel urgency at a 40.5% cutoff (AUROC 0.74, 95% CI 0.62-0.87). Our analysis of 490 images showed median StO2 values for Mayo endoscopic subscores (MES) 0, 1, 2, and 3 as 52% (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 StO2 was 49% (IQR 44%-54%) for Geboes scores 0-2, significantly higher than histologically active disease (Geboes score ≥ 3). At a colonic StO2 cutoff of 45.5%, AUROCs for endoscopically and histologically active diseases were 0.79 (95% CI 0.74-0.84) and 0.72 (95% CI 0.66-0.77), respectively. CONCLUSIONS:StO2 obtained by hypoxia imaging colonoscopy is useful for assessing clinical, endoscopic, and histologic activities of UC, suggesting StO2 may be a novel and objective endoscopic measurement.