Micro-Dosing of Indocyanine Green for Intraoperative Fluorescence Cholangiography

Surgery involving the biliary tree is common but has the potential for serious complications. Adjuncts such as intraoperative cholangiogram and, more recently, indocyanine green (ICG) fluorescence cholangiography, have been used to more accurately define the relevant anatomy and decrease the risk of common bile duct injury. The optimal ICG dose is unknown, but the most commonly cited dose in the literature is 2.5 mg. We describe our experience using micro-dosing of ICG as proof-of-concept for its successful use in the identification of biliary structures.

A video library from a variety of hepatobiliary surgeries which included micro-dosing of ICG was compiled between 2018 and 2020. These videos were retrospectively reviewed and graded for the degree of visualization of biliary structures (complete, partial, none) and the degree of background liver fluorescence (significant, moderate, minimal).

Overall, 40 videos were reviewed; 70% were minimally invasive cholecystectomies. Micro-dosing was used in all patients; complete visualization was achieved in 52.5% of the patients, partial visualization in 40%, and no visualization in 7.6%. Eighty percent of patients had minimal to moderate background fluorescence. Despite ICG micro-dosing, 20% of the patients still had significant liver dye uptake.

ICG cholangiography is an alternative to more invasive means of intraoperative imaging during biliary surgery, but the optimal dose of ICG is unknown. We have used a 0.05 mg micro-dose of ICG to successfully visualize biliary structures and reduce background liver fluorescence. This preliminary report can be used to develop further studies into whether micro-dosing of ICG is associated with improved clinical outcomes.