Near-infrared (NIR) fluorescence imaging has the potential to revolutionize human cancer
surgery by providing sensitive, specific, and real-time intraoperative visualization of normal
and disease processes. We have previously introduced the concept of a low-cost, safe, and
easy-to-use NIR fluorescence imaging system that permits the surgeon to “see” surgical
anatomy and NIR fluorescence simultaneously, non-invasively, with high spatial resolution,
in real-time, and without moving parts [Nakayama et al. Molecular Imaging 1, 365-377
(2002)]. In this study, we present an operational prototype designed specifically for use during
large animal surgery. Such a system serves as a foundation for future clinical studies.
We discuss technical considerations, and provide details of the implementation of subsystems
related to excitation light, light collection, computer, and software. Using the prototype,
and the clinically available NIR fluorophore indocyanine green, we demonstrate vascular
imaging in 35 kg pigs. Cancer-specific applications of this imaging system include
image-guided cancer resection with real-time assessment of surgical margins, image-guided
sentinel lymph node mapping, intraoperative mapping of tumor and normal vasculature,
image-guided avoidance of critical structures such as nerves, and intraoperative detection
of occult metastases in the surgical field. Taken together, this study describes an optical
imaging system engineered for eventual translation to the clinic.