NIR-II fluorescence imaging in liver tumor surgery: A narrative review

In liver tumor surgery, the recognition of tumor margin and radical resection of microcancer focis have always been the crucial points to reduce postoperative recurrence of tumor. However, naked-eye inspection and palpation have limited effectiveness in identifying tumor boundaries, and traditional imaging techniques cannot consistently locate tumors in real time. As an intraoperative real-time navigation imaging method, NIR fluorescence imaging has been extensively studied for its simplicity, reliable safety, and superior sensitivity, and is expected to improve the accuracy of liver tumor surgery. In recent years, the research focus of NIR fluorescence has gradually shifted from the first near-infrared window (NIR-I, 700–900 nm) to the second near-infrared window (NIR-II, 1000–1700[Formula: see text]nm). Fluorescence imaging in NIR-II reduces the scattering effect of deep tissue, providing a preferable detection depth and spatial resolution while significantly eliminating liver autofluorescence background to clarify tumor margin. Developing fluorophores combined with tumor antibodies will further improve the precision of fluorescence-guided surgical navigation. With the development of a bunch of fluorophores with phototherapy ability, NIR-II can integrate tumor detection and treatment to explore a new therapeutic strategy for liver cancer. Here, we review the recent progress of NIR-II fluorescence technology in liver tumor surgery and discuss its challenges and potential development direction.