Clinical trial Radiotracer for tumor progression/activity- FET-PET MRI 18F-Fluciclovine PET-MRI in High-grade Glioma funded 70K ClinicalTrials.gov Identifier: NCT05553041 Researcher-Dr. Nabavizadeh and Dr. Kline The purpose of this study is to see if 18F-fluciclovine (Axumin®) PET imaging is useful and safe in the management of children with High-Grade Gliomas. Investigators seek to determine if this imaging will help doctors tell the difference between tumor growth (progression) and other tumor changes that can occur after treatment.