Hypoxia is recognized to be an independent predictor of clinical outcome in oncology. PET using [18F]-FMISO has been described to be useful for the non invasive assessment of hypoxia in cancer. The use of this radiotracer for brain tumours is very limited and there is no standard to acquire and quantify [18F]-FMISO uptake. So there is a need for a methodological evaluation of this PET tracer The purpose of this research is to define optimal parameters for acquisition and data exploitation to quantify [18F]-FMISO uptake and so predict clinical outcome in glioblastomas.