This phase II trial is studying how well positron emission tomography (PET) scan using 18F-fluoromisonidazole works when given together with magnetic resonance imaging (MRI) ) in assessing tumor hypoxia in patients with newly diagnosed glioblastoma multiforme (GBM). Diagnostic procedures, such as MRI and PET scan using 18F-fluoromisonidazole (FMISO), may help predict the response of the tumor to the treatment and allow doctors to plan better treatment.