10138-ST-7 Intraoperative 5-ALA Fluorescence Visibility in Glioma Surgery Using Exoscope: Comparison with Microscope and Implications for Automated Detection

Abstract Background 5-Aminolevulinic acid (5-ALA)-induced fluorescence serves as a valuable tool for enhancing tumor visualization during glioma surgery. However, its intraoperative visibility depends on lighting conditions and the type of optical device used. Since 2021, we have introduced an exoscope alongside the conventional surgical microscope. In this retrospective study, we investigated how different optical systems influence 5-ALA fluorescence visibility during glioma surgery. Furthermore, we developed an automated detection system that processes real-time exoscopic video to extract the contours of fluorescent areas based on luminance and chroma analysis. Methods We retrospectively analyzed 169 adult patients who underwent glioma resection at our institution between April 2017 and March 2025. The surgical viewing systems included a microscope (n = 84), an exoscope (n = 64), and an endoscope (n = 7). Fluorescence visibility was classified into three categories: strong, vague, and none. The automated detection system was applied to cases performed with the exoscope after May 2023. Results and Conclusion In WHO grade 4 gliomas, all cases using the exoscope demonstrated either strong or vague fluorescence, whereas a subset of microscope cases showed no visible fluorescence. The exoscope provided consistent visualization even in cases where fluorescence was difficult to recognize under the microscope. Additionally, the automated system accurately delineated fluorescent regions and enabled real-time overlay onto standard-light images. This facilitated safer tumor resection while preserving cortical arteries. The integration of exoscopic imaging and real-time image processing represents a promising advancement in fluorescence-guided glioma surgery.