Color differences of intraprocedural bleeding between white light and red dichromatic imaging during endoscopic submucosal dissection: a post hoc analysis of a multicenter, open-label, randomized controlled trial (with videos)

Background: Red dichromatic imaging (RDI) is an image-enhanced endoscopy expected to improve the visibility of bleeding source. We aimed to analyze color difference and hemostasis time between white light imaging (WLI) and RDI during endoscopic submucosal dissection (ESD). Methods: This was a single-center post hoc analysis of a multicenter randomized controlled trial (RCT) to verify the efficacy and safety of RDI in hemostasis during ESD. We included patients with intraprocedural bleeding enrolled in an RCT at our institution. We extracted videos of intraoperative bleeding and annotated bleeding source in each frame. We calculated the mean color difference (ΔE) between the bleeding source and eight surrounding areas for each frame. We also evaluated the visibility score of the bleeding source. Results: Thirty-nine and 63 hemostasis were performed among 30 patients in WLI (n = 16) and RDI (n = 14) groups. The ΔE ± standard error (SE) was significantly higher in RDI than in WLI (14.2 ± 0.5 and 11.7 ± 0.8, p = 0.01). The ΔE ± SE for spurting and oozing hemorrhage was 9.3 ± 0.9 and 13.6 ± 0.7 (p = 0.02) and 12.4 ± 1.0 and 14.5 ± 0.5 (p = 0.47), and mean hemostasis time ± SE (seconds) was 44.5 ± 7.9 and 25.9 ± 3.8 (p = 0.04) in WLI and RDI, respectively. The mean visibility score was significantly higher in RDI than in WLI (3.36 ± 0.7 vs 2.78 ± 1.0, p < 0.01). Conclusion: RDI demonstrated a higher color difference in the bleeding source than WLI. This could improve the visibility of a bleeding source, particularly spurting hemorrhage.