MRI in Assessing Hypoxia in Patients With Localized Prostate Cancer Undergoing Stereotactic Body Radiation Therapy

OBJECTIVES: * To characterize the status of global hypoxia within the prostate before stereotactic body radiotherapy (SBRT) as assessed by blood-oxygen-level-dependent and tissue-oxygen-level-dependent MRI. * To characterize tumor vasculature and metabolism within the prostate before SBRT as assessed by dynamic contrast-enhanced MRI and magnetic resonance spectroscopic imaging, respectively. * Correlate prostate and normal tissue hypoxia before SBRT with clinical outcomes (toxicity and biochemical \[PSA\] control) after SBRT. OUTLINE: Within 1-3 weeks before beginning stereotactic body radiotherapy, patients undergo T2-weighted anatomic MRI, magnetic resonance spectroscopic imaging, blood-oxygen-level-dependent and tissue-oxygen-level-dependent MRI, and dynamic contrast-enhanced MRI.