Glioblastoma multiforme (GBM) represent the most common primary brain malignancy and prognosis remains poor. The most common subtype is glioblastoma which has a 5-year survival rate of approximately 5%. Despite advances in MRI techniques, accurately determining total extent of tumor remains a challenge. The result is incomplete treatment resulting in reduced survival or overtreatment resulting in avoidable treatment related morbidity. A more accurate means of assessing tumor extent is needed to guide management to improve patient survival and quality of life.

Inclusion Criteria:

Each participant must meet all of the following inclusion criteria to participate in this study:

• ≥ 18 years of age
• Diagnosis of glioblastoma multiforme
• Post-maximally safe surgical resection
• No prior radiation or systemic treatment for high grade glioma
• Able to tolerate PET/MRI scan with intravenous contrast
• Willing to provide informed consent

Exclusion Criteria:

All participants meeting any of the following exclusion criteria at baseline screening will be excluded from participation in this study:

• MRI contraindication
• Creatinine clearance < 30mL/min
• Inability to lie still for 60 minutes
• Gadolinium allergy
• Positive pregnancy test
• Breastfeeding
• Patient unable to follow the protocol for any reason

The study population will consist of both males and females over 18 years of age post maximally safe resection of glioblastoma multiforme and intent to treat with stereotactic radiation.