Clinical application of indocyanine green-fluorescence imaging during hepatectomy

Abstract

In hepatobiliary surgery, the fluorescence and bile excretion of indocyanine green (ICG) can be used for real-time visualization of biological structure. Fluorescence cholangiography is used to obtain fluorescence images of the bile ducts following intrabiliary injection of 0.025-0.5 mg/mL ICG or intravenous injection of 2.5 mg ICG. Recently, the latter technique has been used in laparoscopic/robotic cholecystectomy. Intraoperative fluorescence imaging can be used to identify subcapsular hepatic tumors. Primary and secondary hepatic malignancy can be identified by intraoperative fluorescence imaging using preoperative intravenous injection of ICG through biliary excretion disorders that exist in cancerous tissues of hepatocellular carcinoma (HCC) and in non-cancerous hepatic parenchyma around adenocarcinoma foci. Intraoperative fluorescence imaging may help detect tumors to be removed, especially during laparoscopic hepatectomy, in which visual inspection and palpation are limited, compared with open surgery. Fluorescence imaging can also be used to identify hepatic segments. Boundaries of hepatic segments can be visualized following injection of 0.25-2.5 mg/mL ICG into the portal veins or by intravenous injection of 2.5 mg ICG following closure of the proximal portal pedicle toward hepatic regions to be removed. These techniques enable identification of hepatic segments before hepatectomy and during parenchymal transection for anatomic resection. Advances in imaging systems will increase the use of fluorescence imaging as an intraoperative navigation tool that can enhance the safety and accuracy of open and laparoscopic/robotic hepatobiliary surgery.

Keywords: Indocyanine green (ICG); colorectal liver metastasis (CRLM); fluorescence imaging; hepatocellular carcinoma (HCC); intraoperative cholangiography; liver resection.

Conflict of interest statement

Conflicts of Interest: The authors have no conflicts of interest to declare.

Figures

Figure 1

Fluorescence cholangiography following intraoperative intravenous injection of indocyanine green (2.5 mg) shows the confluence of the right and let hepatic ducts, enabling surgeons to determine the division point of the Lt.HD during left hepatectomy. Lt.HD, left hepatic duct; Rt.HD, right hepatic duct; CHD, common hepatic duct.

Figure 2

Fluorescence imaging of hepatic tumor (CRLM). Fluorescence imaging following preoperative intravenous injection of indocyanine green (ICG), clearly showing a CLRM located in hepatic segment VIII as a rim-fluorescing lesion during laparoscopic hepatectomy. (A) White-light color image; (B) monochromatic fluorescence image; (C,D) pseudocolor fusion images of a fluorescence and a white-light color image.

Figure 3

Identification of hepatic segments by dye-staining technique with concomitant use of indigo-carmine and indocyanine green. Fusion pseudocolor fluorescence image on color image (right), clearly showing the boundaries of hepatic segment VI. The blue stain on the liver surface is unclear because of fibrosis and the irregular surface of the liver due to cirrhosis. In this case, a laparoscopic fluorescence imaging system was used during open hepatectomy.

Figure 4

Fluorescence imaging systems in laparoscopic and open surgery. (A) In laparoscopic surgery, surgeons always watch a TV monitor to obtain white-light and fluorescence images, when needed; (B) during open surgery, surgeons must look from the field of operation to each monitor used for intraoperative diagnosis, such as intraoperative ultrasonography (white arrow) and fluorescence imaging (yellow arrow). Use of a laparoscopic imaging system equipped with a short-length laparoscope during open surgery (yellow arrowhead).