IMG-138. LIFE: A Low-resource Intraoperative Fluorescence-Enabled microscope for surgical oncology

Abstract Fluorescence-guided surgery (FGS) improves resection in aggressive brain cancers by allowing accurate visualization of tumor tissue. However, its adoption in low-resource settings such as low- and middle-income countries (LMICs) is limited due to the high cost of commercial fluorescence microscopes. Our aim was to build a Low-resource Intraoperative Fluorescence-Enabled (LIFE) microscope as an affordable technology alternative, targeting tumor biomarkers currently supported by commercial systems: protoporphyrin IX (PpIX) and fluorescein sodium (FS). We modified an inexpensive first-generation white-light surgical microscope by replacing its lighting with a custom-designed light source. This illumination can be switched between white and conventional fluorescence blue light modes (e.g., BLUE400, FL400). Further, we enable simultaneous visualization of fluorescence and anatomy in a novel imaging mode called GlioView, where we ensure that the red part of the visualized spectrum comes only from PpIX fluorescence, while the blue-green part shows anatomy to enable uninterrupted resection. We tested the optical performance of LIFE against a commercial Zeiss Kinevo microscope and observed sub-millimeter resolution and low distortion, with excellent color reproduction. LIFE provides 2-3× higher illumination power compared to the Zeiss microscope, enhancing sensitivity for detecting tumor biomarkers (minimum detection 300 ng/ml, as compared to Zeiss’ 600 ng/ml) while conforming to safety limits. In studies on a rat glioblastoma model, LIFE showed superiority in co-visualizing tumor and anatomy (e.g., vasculature) in GlioView mode compared to the conventional BLUE400/FL400 fluorescence modes. The cost of LIFE was less than ~1/100th the typical price of a commercial FGS surgical microscope. The LIFE microscope offers an affordable and high-performance alternative, optically equivalent to commercial FGS systems, and potentially allowing broader adoption of FGS in LMICs to elevate the standard of neurosurgical care.