Malignant gliomas include hypoxic cells due to both excessive consumption and insufficient supply of oxygen within the tumor. Intratumoral hypoxic conditions are disadvantageous in term of the production of peroxide radicals, which induces DNA damage under irradiation. Cancer stem cells existing within hypoxic tumor tissue have also been considered to represent a likely cause of radioresistance. In glioblastoma, hypoxic conditions play an important role in the development of tumor progression.

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... herefore, we performed PET using 11 C-methionine for detecting extent of tumor, and using 18 F-FRP170 ( 18 F-FRP170 PET) for detecting hypoxic cells in malignant brain tumors. We also examined on 18 F-FRP170 PET with intratumoral oxygen pressure (tpO 2 ) within glioblastoma measured using oxygen microelectrodes during tumor resection. Furthermore, we analyzed hypoxia-related genes, such as HIF-1 and VEGF, in high or low uptake areas of 18 F-FRP170 PET. Mean tpO 2 was significantly lower in the high-uptake area than in the low-uptake area. The specimens obtained from high-uptake areas, showed the increased expression of hypoxia-related genes. These findings suggest that high accumulation on 18 F-FRP170 PET represents viable hypoxic tissues in glioblastoma.