Intraoperative Real-Time Near-Infrared Image-Guided Endoscopic Endonasal Surgery for Pituitary Tumors

Background: For endoscopic endonasal surgery of pituitary tumors, tissue identification and intraoperative judgment depend largely on surgeon expertise. In the present study, we assess whether the delayed-window indocyanine green (ICG) technique can identify pituitary gland tumors in real-time during surgery and analyze the mechanism of ICG fluorescence in the pituitary gland and tumor. Methods: Twenty-five patients with a pituitary adenoma were administered 12.5 mg of ICG intravenously during surgery. Thereafter, near-infrared (NIR) visualization was performed from 0 to 180 minutes. Only 8 patients underwent dynamic contrast-enhanced perfusion magnetic resonance imaging (MRI) owing to predicaments with insurance coverage. Consequently, we analyzed these 8 patients extensively. Results: The pituitary gland and pituitary adenoma were visualized in all 25 patients with NIR fluorescence. The relative ratio of the fluorescence emission of the normal gland to that of the tumor (signal/background ratio [SBR] of the normal gland vs. the tumor) had increased after 15 minutes, peaking (5.8) at 90 minutes, demonstrating that the pituitary gland was distinctly visualized during that period. The tumor/blood (SBR tumor) and normal gland/blood (SBR gland) NIR fluorescence was significantly and positively correlated with each transfer constant on dynamic contrast-enhanced MRI, indicating vascular permeability. Conclusions: The results from the present study exhibit the utility of the delayed-window ICG technique in distinguishing the normal pituitary gland from a tumor during endoscopic endonasal surgery from 15 to 90 minutes after ICG administration. Permeability can contribute to gadolinium enhancement on MRI, as well as ICG retention and NIR fluorescence in a normal pituitary gland and tumor.