• Participants who have the appearance of high-grade glioma (HGG, WHO Grade 3 and 4, including GBM) on MR imaging are allowed to consent and will undergo the procedure if the frozen is consistent with HGG

∙ OR

• Participants with a history of histologically-confirmed diagnosis of high- grade glioma that are undergoing resection of a recurrent/progressive tumor that is likely recurrent/progressive high- grade glioma as identified on preoperative MR imaging

• Age ≥ 18 years old

• Volumetric MRI within 1 month prior to surgery

• Karnofsky performance status of 60 or higher

• The participant (or legally acceptable representative if applicable) provides written informed consent for the trial.

• Participants must be considered appropriate neurosurgical candidates with the following screening/baseline laboratory values within 1 month prior to surgery:

‣ Absolute neutrophil count ≥ 1500/µL

⁃ Platelets ≥ 100 000/µL

⁃ International normalized ratio (INR) OR prothrombin time (PT) Activated partial thromboplastin time (aPTT) ≤1.5 × Upper limit of normal (ULN) unless participant is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants

⁃ Urine or Serum Pregnancy Test = Negative (Not applicable to participants with bilateral oophorectomy and/or hysterectomy or to those participants who are postmenopausal).