Study of Gamma-Knife Radiosurgery Using Magnetic Resonance Imaging (MRI) Spectroscopy for Recurrent Glioma

Inclusion Criteria: 1. Histologically confirmed glioblastoma, gliosarcoma, anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic oligoastrocytoma, malignant glioma not otherwise specified, low-grade astrocytoma, low-grade oligodendroglioma, low-grade oligoastrocytoma, or low-grade glioma not otherwise specified. 2. Prior first-line treatment with surgery or biopsy followed by fractionated radiotherapy with concurrent temozolomide-containing chemotherapy is required for malignant (grade III or IV) glioma patients. Additional prior chemotherapy is allowed, without limitation on number of recurrences. In patients with low-grade tumors, neither prior radiotherapy nor prior chemotherapy is required. 3. An interval of \> 2 months since completion of fractionated radiotherapy. 4. Age \> 18 years 5. Life expectancy of at least 8 weeks. 6. Karnofsky Performance Status score (KPS) of ≥ 60 7. Documented recurrent disease: Recurrent disease is defined either as histological confirmation of tumor, as an increase in tumor size of at least 25% based upon serial MR images, or as development of a new site of disease. * Tumor size will be calculated using the sum of the largest cross-sectional perpendicular diameters of contrast-enhancing tumor for high-grade tumors, the sum of the largest cross-sectional perpendicular diameters of FLAIR abnormality for low-grade tumors, or as worsened spectroscopic characteristics for any tumor type (development of ≥ 2 new voxels with CNI ≥ 3, or ≥ 25% increase in the sum of the CNI ratios within a group of previously abnormal voxels \[where abnormal is defined as CNI ≥ 3\]). * Disease must be evaluable, but does not need to be measurable. * The target site for GKS does not need to be located in a previously-irradiated area. 8. Eligibility for gamma-knife radiosurgery: The decision to treat with gamma-knife radiosurgery will be made by a consensus of the radiation oncology, neurosurgery and neuro-oncology co-chairs or their alternates at the weekly Brain Tumor or Gamma-Knife Tumor Conferences. The MRS defined target volume must be ≤ 15 cc. and not involving eloquent brain (speech/language cortex, motor/sensory cortex, basal ganglia, brainstem, or corpus callosum 2) on an MRI done within 14 days of the planned GKS procedure. 9. BUN \< 25 and Cr \< 1.7 10. Negative pregnancy test at the time of GKS in any patient who could be pregnant. 11. Willingness to forego additional therapy until evidence of disease progression. 12. Signed and witnessed informed consent and signed authorization for the release of their protected health information. Exclusion Criteria: 1. MRS defined tumor volume greater than 15 cc. 2. MRS defined tumor volume involving eloquent brain (speech/language cortex, motor/sensory cortex, basal ganglia, brainstem, or corpus callosum). 3. Concurrent treatment with chemotherapy. 4. Active infectious process requiring IV antibiotics. 5. History of any other cancer (except non-melanoma skin cancer or carcinoma in-situ of the cervix), unless in complete remission and off of all therapy for that disease for a minimum of three years. 6. Other major medical illness judged by the investigator to preclude prolonged follow-up. 7. Any condition that compromises compliance with the objectives and procedures of this protocol, as judged by the principal investigator.