Thus, the non-invasive determination and monitoring of the oxygenation status of tumours is of importance to classify patients' outcome and modify therapeutic strategies in those tumours. Actually the oxygenation status of individual tumours is not assessed routinely. Numerous different approaches have been used to identify hypoxia in tumours. Eppendorf oxygen probe measurements (pO2 histography) may be considered as a 'gold standard' for hypoxia in human malignancies. However, it is an invasive method being confined to superficial, well accessible tumours and requires many measures. PET using [18F]Fluoro-deoxyglucose ([18F]-FDG), allows non-invasive imaging of glucose metabolism and takes a growing place in cancer staging, but [18F]-FDG can't assess correctly the oxygenation status of tumours and is not suitable for brain tumor. PET with appropriate radiotracers enables non-invasive assessment of presence and distribution of hypoxia in tumours. Nitroimidazoles are a class of electron affinic molecules that were shown to accumulate in hypoxic cells in cultures and in vivo. [18F]-FMISO is the most frequently employed tracer; its intracellular retention is dependent on oxygen concentration. Consequently [18F]-FMISO has been used as a non-invasive technique for detection of hypoxia in human. Different authors have demonstrated that it is suitable to localize and quantify hypoxia. Thus, [18F]-FMISO PET has been studied to evaluate prognosis and predict treatment response. However, some investigators report an unclear correlation between Eppendorf measurements and standardized uptake values (SUV). This observation may be explained by the structural complexity of hypoxic tumour tissues. Nevertheless, there is a need of standardized procedures to acquire and quantify [18F]-FMISO uptake. Actually the use of this tracer is very limited in clinic and the academic studies have included small populations of patients and suffer of the heterogeneity of technical procedures.