Multiparametic Metabolic and Hypoxic PET/MRI for Disease Assessment in High Grade Glioma

Inclusion Criteria: 1. Histologically confirmed newly diagnosed grade III or grade IV glioma treated with standard of care external beam radiation therapy (RT). For diffuse midline glioma involving the pons (diffuse intrinsic pontine glioma), histological confirmation is not required. Surgical resection of the glioma prior to RT and/or concurrent temozolomide (TMZ) with RT are allowed but not required. 2. 10 years of age or older at the time of enrollment 3. Able to undergo PET/MRI without anesthesia or sedation. Minimal sedation with an anxiolytic such as alprazolam used routinely for SOC MRI is allowed. 4. Females with childbearing potential must have a negative urine β-hCG test on the day of procedure or a serum beta-hCG test within 48 hours prior to the administration of FET or FMISO. 5. ECOG performance score of 2 or better in adults. For patients less than 16 years of age, Modified Lansky score ≥ 60. 6. Life expectancy greater than 12 weeks. Exclusion Criteria: 1. Recurrent glioma 2. Use of bevacizumab or an investigational therapeutic drug for any indication within 3 months prior to the imaging study. 3. Pregnancy or breast feeding 4. Inability to complete PET/MRI scans. 5. Significant renal dysfunction (estimated GFR \< 30 mL/min) 6. Any condition which may interfere with ability to participate in or complete all study-related activities as assessed by the study team 7. Time interval greater than 12 weeks between the completion of RT and performance of FET and FMISO PET/MRI studies.