This pilot clinical trial studies fluordeoxyglucose (fludeoxyglucose) F-18 (FDG) positron emission tomography (PET)/computed tomography (CT) in monitoring very early therapy response in patients with glioblastoma. Diagnostic procedures, such as FDG PET/CT, may help measure a patient's response to earlier treatment. Chemotherapy can induce very rapid changes to the tumor's glucose consumption which can be measured with imaging. FDG PET/CT shortly after the start of therapy may help identify very early therapy response in patients with glioblastoma.

PRIMARY OBJECTIVES:

I. To assess very early response to therapy in glioblastoma patients using 18F-FDG PET/CT.

II. Evaluate very early changes in FDG uptake within 48 hours of start of therapy and correlate them with objective response parameters such as Response Assessment in Neuro-Oncology (RANO) and survival.

OUTLINE:

Patients undergo standard FDG PET/CT scan 6-8 weeks before start of chemotherapy and one additional FDG PET/CT scan within 48 hours of the start of chemotherapy.

Inclusion Criteria:

• Patients with histologically proven high grade glioma
• Intention to start therapy

Exclusion Criteria:

• Severe psychiatric illness
• Inability to give written consent
• Breast feeding / pregnancy