Fluoroethyltyrosine for the Evaluation of Intracranial Neoplasm

This study is testing a special type of PET scan (a brain imaging technique) using a tracer called FET (fluoroethyltyrosine) to better evaluate brain tumors. The goal is to see if this scan can more accurately detect whether a brain tumor is growing back after treatment, or help doctors plan surgery or radiation more precisely. **You may be eligible if...** - You are older than 3 years old - You have a brain tumor and are either: being evaluated for possible recurrence after treatment (surgery/radiation), OR being assessed before planned surgery or biopsy - You have a suspected high- or low-grade brain tumor, or brain metastases **You may NOT be eligible if...** - You are unable to undergo PET or MRI/CT scans (e.g., certain metal implants) - You are unlikely to comply with study procedures Talk to your doctor to see if this trial is right for you.