Infrared endoscopic system for bleeding-point detection after flushing with indocyanine green solution (with videos)

Background: infrared endoscopy is used to visualize vessels in the GI tract. By applying this system, we developed a new method to visualize a bleeding point during endoscopic resection. Objective: This study aimed to evaluate the ability of infrared endoscopy to detect a bleeding point during endoscopic resection and to elucidate the mechanism required for clear visualization of a bleeding point by in vitro color analysis. Design: Observational case series. Setting: A cancer-referral center. Patients and Interventions: A total of 10 bleeding sites were observed during endoscopic resection of upper-GI cancers by infrared endoscopy after flushing with inclocyanine green (ICG) solution (0.125 mg/mL water). Main Outcome Measurements: Detection of bleeding points. Results: Bleeding points were identified in all bleeding sites by infrared endoscopic viewing. Bleeding points were displayed in white, whereas, an ulcer bed was in blue and pooled blood was a blue-to-gray color. By in vitro color analysis, blood was white, blood twice diluted with ICG solution was dark blue, and blood 4-times diluted with ICG solution was light blue on infrared endoscopic views. Color differences with blood dilution were more obvious in an infrared endoscopic view compared with a conventional endoscopic view. Blood thickness, movement, and clotting did not influence the color differences. Limitations: Uncontrolled study. Conclusions: We reported a flushing method by which we could detect all bleeding points during endoscopic resection. Clear visualization of bleeding points comes from differences in blood and ICG concentration between spurting and pooled blood.