Endoscopic identification of colorectal cancer margin by indocyanine green fluorescence imaging

AIM: We assessed whether indocyanine green (ICG) fluorescence is effective for endoscopic tattooing in colorectal cancer surgery using a photodynamic eye (PDE) camera and fluorescent endoscope. METHODS: Between June 2014 and February 2018, 39 patients-17 patients with early and 22 patients with advanced colorectal cancer respectively-were enrolled and underwent preoperatively colonoscopic tattooing using 0.5 mL/time (n = 28 cases) or 0.3 mL/time (n = 11 cases) of ICG three days before laparotomy or laparoscopic surgery. We observed lesions using a PDE camera or a fluorescent endoscope during laparotomy or laparoscopic surgery. Moreover, we assessed the fluorescent luminance and fluorescent size of resected lesions intra- and post-operatively, respectively. Patients’ medical records and operation videos were retrospectively assessed to evaluate the visibility, duration, and adverse effects of tattooing. RESULTS: It was possible to obtain a useful fluorescent image with ICG fluorescent labeling and to determine the resection range in all cases. No difference regarding the distance from cancer’s oral margin to the ICG oral margin according to the volume of ICG (0.5 mL/time vs. 0.3 mL/time) was observed, but a significant difference concerning the distance from cancer’s oral margin to the ICG oral margin between early colorectal cancer and advanced cancer was noted (p = 0.0038). CONCLUSION: In our experience, the ICG fluorescence imaging system seems to be simple, safe, and effective. However, the use of ICG fluorescence in endoscopic tattooing necessitates the exploration of additional information such as the volume of the ICG solution and the timing of the ICG injection.