Indocyanine Green-Enhanced Fluorescence-Guided Surgery: Lymphatic Navigation, Perfusion Evaluation and Future Perspectives

Indocyanine green (ICG) is the most commonly used fluorophore in fluorescence imaging. Medical applications started in the 1950s, mainly for functional evaluations. Several perfusion and angiographic applications have been implemented with the advancement of fluorescence imaging. Fluorescence-guided imaging has widely evolved in recent years. With the implementation of advanced technologies, surgeons became able to perform more complex interventions with a minimally invasive technique and started to develop an interest in intraoperative imaging applications. ICG has applications in several surgical fields enabling real-time visualization of structures of interest and giving information that normally are uncertain under naked eyes. Tissue perfusion assessment, anatomic distinction, lymphography and other implementations have been described in general surgery, gynecology, urology, colorectal surgery and surgical oncology practice. The application rationale of fluorescence lies in the possibility of giving the surgeon any possible aid in the correct evaluation of anatomical and functional aspects to improve the quality and safety of the surgical act. Despite the large number of published experiences and applications, some issues of ICG fluorescence need to be more thoroughly analyzed and developed in the future, like timing and volume of administration, visualization system features, standardized protocols, reproducible measurement systems and quantitative evaluations.