[Intraoperative photo-dynamic diagnosis of brain tumors]

Conventionary, we use 5-aminolevulinic acid (5-ALA) for photo-dynamic diagnosis in the removal of malignant gliomas. 5-ALA is converted to protoporphyrin IX (PpIX) in the body and emits red fluorescence, with the excitation of blue-violet light. As PpIX preferentially accumulates in the tumor tissue in comparison with normal tissue, this red fluorescence becomes a good hallmark for discrimination between normal and tumor tissues, especially in malignant gliomas, which have infiltrative characteristics. Approximately 80% to 90% of the malignant gliomas show this red fluorescence in surgery as mentioned above, while only a limited number of metastatic brain tumor cases do. In the surgery for metastatic brain tumor and lesionectomy for radiation necrosis and neurodegenerative disease, white matter around the lesion showed vague fluorescence, which also provided us with a hallmark in the surgery. Additionally, in meningioma, some tumors showed the red fluorescence, which is especially helpful in the removal of the infiltrative portion in the bone and normal parenchyma. In this paper, we also discuss high quality international reserch on 5-ALA-guided surgery for malignant gliomas. The most important point in 5-ALA-guided microsurgery is the use of good equipment that can provide sufficient operative fields even under fluorescence mode.