ICG fluorescence imaging of the liver surface clearly identified regions of cholestasis caused by tumor invasion of the bile duct or by thrombi.

In open laparotomy, fluorescence images of the liver surface were obtained intraoperatively with a fluorescence imaging system (PDE; Hamamatsu Photonics, Hamamatsu, Japan) composed of a charge-coupled device camera that excluded light with wavelengths of less than 820 nm and 36 light-emitting diodes with a wavelength of 760 nm [1, 4]. The cholestatic regions on the surface of the liver were clearly delineated with fluorescence imaging (Fig. 30.3), whereas using a laparoscopic system fluorescence in the same regions was relatively weak (Fig. 30.4). The latter result reflects the fact that, in the laparoscopic system, the fluorescence strength cannot be adjusted.