Evaluation of 18F-Fluciclovine Positron Emission Tomography - Magnetic Resonance Imaging (PET-MRI) in LGG

Eligibility Criteria

• * LGG including the brainstem and supratentorial only , (WHO grade I-II), confirmed by biopsy unless in Neurofibromatosis type 1 (NF1) participants with classic appearance
• * Participants must have evaluable disease (1x1 cm tumor on MRI; enhancing + non-enhancing tumor)
• * Scheduled to receive systemic therapy
• * Performance Score: Karnofsky ≥ 50 for participants \> 16 years of age and Lansky ≥ 50 for participants ≤ 16 years of age. Participants who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score.
• * Age between ≥ 1 years but ≤21 years at time of study registration
• 1. Inability to tolerate imaging procedures in the opinion of an investigator or treating physician
• 2. Pregnant participants
• 3. Patient who would require sedation or anesthesia for imaging beyond SOC.
• 4. Participants who weigh less than 8 kg.
• 5. Participants who cannot avoid contact with a pregnant woman or infant for at least 12 hours following injection.
• 6. Participants with a history of abnormal kidney function or creatinine \>= CTCAE v5.0 grade 2 at time of study registration.
• 7. Participants with primary tumors of the spinal cord.