Utility of Perfusion MRI to Detect Radiation Necrosis in Patients With Brain Metastases

PRIMARY OBJECTIVE: I. To prospectively determine the sensitivity and specificity of dynamic susceptibility contrast (DSC)-MRI parameters in detecting tumor recurrence versus radiation necrosis for brain metastases treated with stereotactic radiosurgery (SRS). SECONDARY OBJECTIVES: I. To correlate radiographic diagnoses with pathologic diagnoses when surgical resection is clinically indicated. II. To correlate baseline relative cerebral blood volume (rCBV) values and other hemodynamic parameters with tumor primary histology. III. To assess overall survival, local failure, distant brain failure and neurologic death. OUTLINE: Participants undergo a diagnostic MRI with and without contrast and treatment planning DSC perfusion MRI series before receiving SRS at 4-6 weeks after SRS, and then every 3 months unless clinically indicated sooner.