Near-infrared cholecysto-cholangiography with indocyanine green may secure cholecystectomy in difficult clinical situations: proof of the concept in a porcine model

Biliary injuries remain a major concern in laparoscopic cholecystectomy. New intraoperative guidance modalities, including near-infrared fluorescence cholangiography, are under evaluation. Initial results showed limitations in visualizing the biliary tree in specific clinical situations. The aim of this study was to examine the feasibility and potentiality of fluorescence cholecysto-cholangiography performed with a direct injection of indocyanine green (ICG) in the gallbladder and to compare it to systemic injection in such situations. Seven pigs were included in this non-survival study. In two pigs, the gallbladder was punctured by a percutaneous needle, and 1 mL of ICG in different concentrations (0.001, 0.01, 0.1, and 1 mg/mL) was sequentially injected. Visibility and pattern of the fluorescent signal around Calot's triangle were examined and compared with those of two control pigs receiving 2.5 mg of intravenous ICG, 30 min prior to the operation. Different scenarios of cholecystitis were modeled using an injection of a mixture of blood and agarose gel around Calot's triangle area in the remaining three pigs, and the applicability of direct intragallbladder injection methods was evaluated. The fluorescent signal was identified immediately after intragallbladder injection, and the cystic duct became visible by 0.1 and 1 mg/mL of ICG. The whole cystic duct and the infundibulum of the gallbladder were clearly enhanced by intragallbladder ICG injection, but not by systemic injection. In the cholecystitis models, the cystic duct could be identified only after partial dissection, and fluorescence visualization of the gallbladder infundibulum provided crucial information to find the correct starting point of dissection. Fluorescence cholecysto-cholangiography through direct intragallbladder ICG injection could rapidly provide an adequate visualization of gallbladder neck and cystic duct and might be a valid option to increase the safety of cholecystectomy in case of cholecystitis.