The effect of Excimer Dye Laser(EDL) on photodynamic therapy(PDT) has been investigated in Ethylnitrosourea(ENU)-induced rat glioma model that is more similar to human glioma. Tumor location and size before and after PDT were determined by continuous slices of Magnetic Resonance Image(MRI). PDT was carried out with an optical fiber tip contacting with the brain surface nearer to the tumor, 48 hours after intravenous administration of hematoporphyrin derivatives(HpD) (2mg/kg). The anti-tumor effects were studied histologically about 4weeks after laser irradiation. In result, MRI after PDT implied tumor necrosis and no recurrence at the target area. Histological examination suggested that EDL has higher selection to tumor tissue rather than normal brain tissue. In the histological study in border zone between tumor and normal brain tissues after PDT, EDL was more selectively effectual to the tumor cells than Argon Dye Laser(ADL), although ADL has been investigated for glioma models established by implanting C6 cells, as reported previously in Part I and II. EDL had not adverse effects such as severe cerebral edema and hemorrhage. In coclusion, EDL in PDT was suggested to be more effectual on tumor cells and less invasive on the surrounding normal brain tissues.
