Indocyanine green injection for detecting sentinel nodes using color fluorescence camera in the laparoscopy-assisted gastrectomy

Background and Aim: We seek for the accurate and simple method for detecting sentinel nodes of gastric cancer which can be popularized in community hospitals. The indocyanine green (ICG) fluorescence-guided method is reported to be sensitive. However, the ordinal fluorescence cameras have gray scale imaging and require a dark room. We have developed a new device, Hyper Eye Medical System (HEMS) which can simultaneously detect color and near-infrared rays and can be used under room light. This study was planned to examine whether submucosal injection of 0.5mL×4 of 50μg/mL ICG on the day before operation is the adequate administration for detecting sentinel nodes using HEMS in the gastric cancer surgery. Methods: The patients underwent gastrectomy for clinical T1a (mucosa)-T2 (muscularis propria) and clinical N0 were enrolled in the present study. As a preliminary trial, one case each of the ICG 25 and 100μg/mL, injected on the day before operation and intraoperative injection, was examined. Then, 10 cases injected 50μg/mL ICG on the day before operation were examined. Results: The ICG fluorescence of the patient injected 100μg/mL was too intense and that of the patient injected 25μg/mL was too faint. Sentinel lymph nodes were detected in all of 10 cases injected 50μg/mL, the day before operation and number of sentinel lymph nodes per patient was 3.6±2.1. Metastasis was observed in one case. All of ICG fluorescence-positive sentinel nodes were positive for the metastasis. In the patient who underwent intraoperative injection, sentinel lymphatic basins could be identified. Conclusion: The present study shows that HEMS-guided abdominal surgery is feasible under room light. Submucosal injection of 0.5mL×4 of 50μg/mL ICG on the day before operation is the adequate administration for detecting sentinel nodes using HEMS in the gastric cancer surgery.