ENHANCED OPTICAL IMAGING OF RAT GLIOMAS AND TUMOR MARGINS

CURRENT INTRAOPERATIVE METHODS used to maximize the extent of tumor re moval are limited to intraoperative biopsies, ultrasound, and stereota ctic volumetric resections. A new technique involving the optical imag ing of an intravenously injected dye has the potential to localize tum ors and their margins with a high degree of accuracy. In a rat glioma model, enhanced optical imaging was performed and indocyanine green wa s used as the contrast-enhancing agent. In all 22 animals, the peak op tical change in the tumor was greater than in the ipsilateral brain ar ound the tumor and the contralateral normal hemisphere. The clearance of the dye was significantly delayed to a greater extent in the tumor than in the brain around the tumor and the normal brain. After attempt s were made at complete microscopic resection, enhanced optical imagin g of the tumor margins and the histological samples demonstrated a spe cificity of 93% and a sensitivity of 89.5%. Enhanced optical imaging w as capable of outlining the tumor even when the imaging was done throu gh the cranium. The optical imaging of rat gliomas with a contrast-enh ancing dye is able to differentiate between normal brain and tumor tis sue both at the cortical surface and at the tumor margins. The applica tion of these studies in an intraoperative clinical setting may allow for the more accurate determination of tumor margins and may increase the extent of tumor removal.