Comparison between operative findings on malignant glioma by a fluoresceinsurgical microscopy and histological findings

Using a fluorescein surgical microscope that we developed, we performed sur gery on 30 cases of malignant glioma. Operative findings and histological f indings were then compared in five of these cases. Fluorescein sodium was s ystemically administered intravenously as a fluorescent dye. About 20 min a fter intravenous administration, fluorescein activity in the blood decrease d, and the fluorescence was observed only in the area lacking the blood-bra in barrier function, such as tumors; then, resection of the tumor was start ed. The fluorescent regions coincided with the enhanced regions on CT and M RI. Fluorescein spread to the surrounding brain edematous region with time, but its intensity was very different from the tumor-associated one. In the histological examination of intensely fluorescent regions, abnormal tumor blood vessels with a thick wall and a small caliber, or with a thin wall an d a large caliber, were observed. Dense tumor cells were found in these reg ions. On the other hand, in regions with weak or no fluorescence infiltrati on of tumor cells was scant, and no abnormal blood vessels were found. Fluo rescence was not observed in necrotic regions of the tumor center. These hi stological findings coincided with those obtained in large surgical specime n or autopsy, and tumor-cell rich regions seemed to be removed by resecting abnormal vascular regions (fluorescent regions). Enhanced regions on CT an d MRI disappeared after operation by resecting intensely fluorescent region s. These results indicate that the fluorescein surgical microscope develope d by us is a useful aid in operations on malignant glioma.