Inclusion Criteria:  Pathologically diagnosed high-grade glioma (World Health Organization [WHO] grade 3-4). Patients with a radiographically diagnosed high-grade glioma may enroll prior to pathologic confirmation, but would be removed from study if pathology did not confirm the diagnosis of high-grade glioma. Primary tumor located within the supratentorial brain. Recommended to receive definitive radiation therapy. Able to receive MRI scans. Both males and females, and members of all races and ethnic groups are eligible for this trial.  Exclusion Criteria:  Patients with pacemakers, non-titanium aneurysm clips, neurostimulators, cochlear implants, non-titanium metal in ocular structures, or other incompatible implants which makes MRI safety an issue are excluded. Patients that have any significant medical illnesses that in the investigator's opinion cannot be adequately tolerate MRI scan are excluded. Pathology demonstrated low-grade glioma or other benign or non-invasive brain tumor.