Tumor hypoxia as evaluated by [18F]-FMISO PET is associated with the expression of hypoxia markers on a molecular level and is related to angiogenesis. [18F]-FMISO uptake is a mark of an aggressive tumor, almost always a glioblastoma. Our results underline that [18F]-FMISO PET could be useful to guide glioma treatment, and in particular radiotherapy, since hypoxia is a well-known factor of resistance.

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor. This aggressiveness is in part attributed to the closely interrelated phenomena tumor hypoxia and angiogenesis, although few in vivo data exist in human brain tumors. This work aimed to study hypoxia and angiogenesis, in vivo and in situ, in patients admitted with GBM using multimodal imaging. Twenty-three GBM patients were assessed byF-fluoromisonidazole (F-FMISO) PET and conventional and perfusion MRI before surgery. The level and location of hypoxia (F-FMISO uptake, evaluated by tumor-to-blood [T/B] ratio), vascularization (cerebral blood volume [CBV]), and vascular permeability (contrast enhancement after gadolinium injection) were analyzed. The spatial relationship between tumor hypoxia and angiogenesis was assessed by an overlap analysis of the volume of F-FMISO uptake and the volumes of the high CBV regions and the contrast-enhancement regions. A significant correlation was found between hypoxia and hypervascularization, especially for their maximum values (volume of maximal tumor hypoxia vs. relative CBV: = 0.61, = 0.002) and their volumes (hypoxia vs. hypervascularization: = 0.91, < 0.001). A large proportion of the high CBVs collocated with hypoxia (81.3%) and with contrast enhancement (46.5%). These results support the hypothesis of a tight association between hypoxia and angiogenesis. Our results suggest that there is insufficient tumor oxygenation in human GBM, despite increased tumor vascularization.