Inclusion Criteria:

- Contrast-enhancing mass on diagnostic brain CT or MRI strongly suggesting a diagnosis
of WHO grade III or IV glioma

- Karnofsky Performance status (KPS) ≥ 70

- Age ≥18 years

- Subject is able to understand and consent to study

- Glomerular filtration rate (GFR) ≥ 45 ml/minute

Exclusion Criteria:

- Indication for urgent craniotomy to relieve mass effect

- Only stereotactic biopsy indicated because tumour is located in eloquent brain.

- The enhancement on the T1 MRI sequence involves or abuts the basal ganglia

- Previous intracranial malignancy or any invasive malignancy unless free of disease >
5 years

- Prior cranial irradiation

- Contra-indications to systemic radiation exposure: pregnancy or breast feeding

- Subject exceeds the weight limit of the PET scanner bed (204.5 kg)

- Subjects taking medication such as Levodopa for the treatment of Parkinson's Disease

- Allergies or other contraindication to CT contrast or MRI contrast