• Ability to understand and the willingness to sign (or their legally acceptable representative (LAR) must sign) a written informed consent document

• Adults ≥ 18 years old

• Suspicion for or histologically or cytologically confirmed and previously treated HGG or brain metastases from a primary extracranial malignancy

• Lesion size ≥ 1 cm (for the lesion to be biopsied)

• ECOG performance status ≤ 2 (Karnofsky ≥ 60%)

• Planned to undergo biopsy/resection of brain lesion