To evaluate the clinical and technical factors affecting the ability of fluorescence cholangiography (FC) using indocyanine green (ICG) to delineate the bile duct anatomy during laparoscopic cholecystectomy (LC). Application of FC during LC began after laparoscopic fluorescence imaging systems became commercially available. In 108 patients undergoing LC, FC was performed by preoperative intravenous injection of ICG (2.5 mg) during dissection of Calot's triangle, and clinical factors affecting the ability of FC to delineate the extrahepatic bile ducts were evaluated. Equipment-related factors associated with bile duct detectability were also assessed among 5 laparoscopic systems and 1 open fluorescence imaging system in ex vivo studies. FC delineated the confluence between the cystic duct and common hepatic duct (CyD–CHD) before and after dissection of Calot's triangle in 80 patients (74%) and 99 patients (92%), respectively. The interval between ICG injection and FC before dissection of Calot's triangle was significantly longer in the 80 patients in whom the CyD–CHD confluence was detected by fluorescence imaging before dissection (median, 90 min; range, 15–165 min) than in the remaining 28 patients in whom the confluence was undetectable (median, 47 min; range, 21–205 min; P < 0.01). The signal contrast on the fluorescence images of the bile duct samples was significantly different among the laparoscopic imaging systems and tended to decrease more steeply than those of the open imaging system as the target-laparoscope distance increased and porcine tissues covering the samples became thicker. FC is a simple navigation tool for obtaining a biliary roadmap to reach the “critical view of safety” during LC. Key factors for better bile duct identification by FC are administration of ICG as far in advance as possible before surgery, sufficient extension of connective tissues around the bile ducts, and placement of the tip of laparoscope close and vertically to Calot's triangle.

γ-Glutamyltranspeptidase (GGT) is upregulated in a variety of human cancers including primary and secondary hepatic tumors. This motivated us to use γ-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG), a novel fluorophore emitting light at around 520 nm following enzymatic reaction with GGT, as a tool for the intraoperative identification of hepatic tumors. gGlu-HMRG was topically applied to 103 freshly resected hepatic specimens. Fluorescence imaging using gGlu-HMRG identified hepatic tumors with the sensitivity/specificity of 48%/96% for hepatocellular carcinoma, 100%/100% for intrahepatic cholangiocarcinoma, and 87%/100% for colorectal liver metastasis. High gGlu-HMRG fluorescence intensity was positively associated with the incidence of microscopic vascular invasion in HCC and the risk of early postoperative recurrence in CRLM. These results suggest that gGlu-HMRG imaging could not only be a useful intraoperative navigation tool but also provide information related to postoperative disease recurrence.