Primary Objective: To determine the feasibility of interim PET-MRI in high-grade glioma patients undergoing chemoradiation by quantifying the proportion of high-grade glioma patients who are alive at 4 months post-radiation treatment and who have completed two PET scans and abbreviated cognitive testing pre-radiation treatment and at 4 months post radiation treatment.~Secondary Objectives~To determine by machine learning if early changes on FDG-PET correlate with cognitive decline after radiation treatment. Cognitive impairment will be defined as a 1 standard deviation decline on any test.~To determine if baseline serum or cerebrospinal fluid markers or the change from baseline to 1-month are associated with patients with cognitive decline at 4-months after radiation treatment (defined as a 1 standard deviation decline on any test) compared to those without decline.
The purpose of this research study is to see if investigators can predict how brain functioning changes after radiation treatment based on PET scans and blood tests. Most participants experience at least mild decreases in their memory or attention after radiation therapy. Investigators hope that PET scans, lumbar puncture, and blood tests might help investigators predict who might have larger changes in their brain function after radiation.