In this NIH-funded study, the radiotracer 11C-alpha-methyl-tryptophan (AMT) is used in positron emission tomography (PET) to image brain tumors. As an amino acid-derived tracer, AMT is taken up through the large amino acid transporter (LAT1) and metabolized by the enzyme indoleamine 2,3-dioxygenase (IDO). As AMT and its metabolites are not incorporated into proteins, tumor cells accumulate the radiotracer. Data from the PET scan in conjunction with blood levels of AMT and the metabolites allow for the differential diagnoses between primary gliomas vs. metastatic brain tumors, as well as recurrent gliomas from radiation necrosis with a far greater accuracy then the standard imaging modalities used clinically today. AMT-PET also has high prognostic value in predicting patient survival after tumor recurrence. This project is in collaboration with Csaba Juhász, MD, PhD, in the Depts. of Pediatrics and Neurology at the WSU School of Medicine.