10266-ST-8 Intraoperative Near-Infrared Optical Contrast of Indocyanine Green Can Localize Glioblastoma in clinical outcome and basic mechanism

Abstract Introduction Intraoperative fluorescence imaging using Indocyanine Green (ICG) has proven useful for visualizing metastatic brain tumors. We developed the Delayed Window ICG technique (DWIG), which involves administering ICG at a dose of 1. 5 mg/kg more than one hour prior to observation, optimizing both dosage and timing. This technique has been applied to 35 cases of IDH-wildtype malignant gliomas. Methods We analyzed 46 cases of malignant glioma treated with both ICG and 5-aminolevulinic acid (5ALA) as part of a clinical study registered at our hospital since August 2019. Additionally, we compared the prognosis and resection rates with 32 cases that underwent surgery using only 5ALA, without ICG. Results The Signal Background Ratio (SBR), which represents the ratio of fluorescence intensity between the tumor and normal brain parenchyma, was 4.0. The T1 Background Ratio (T1BR), calculated from Gd-MRI images, was 2.3. The fluorescence intensity of ICG was found to correlate with the permeability of the tumor tissue. When comparing the post-operative residual Gd and ICG, the sensitivity was 94%, and the specificity was 73%. The mean survival time for the ICG group was 23.6 months, while for the non-ICG group, it was 21. 8 months, with no significant difference. Conclusion In malignant gliomas, real-time intraoperative fluorescence imaging with ICG was nearly identical to the tumor localization observed with MRI gadolinium contrast. While there was no significant difference in mean survival time, the use of ICG, combined with the enhanced permeability and retention (EPR) effect, suggests potential synergistic effects when used alongside 5ALA. This could further enhance the effectiveness of fluorescence-guided surgery.