Fluorodopa (FDOPA) is a fluorinated analog of levodopa (L-DOPA) used to assess the nigrostriatal dopamine system in vivo with positron emission tomography (PET) in the form of fluorine-18 isotopologue. It is often used for studies requiring repeated imaging, including examinations over the course of a disease and/or the effect of treatment. 18F-labeled FDOPA, which was primarily developed to measure dopamine synthesis in the basal ganglia, has also increasingly been used as a tracer for brain tumor imaging. FDOPA is currently approved for characterization of presynaptic dopaminergic activity in patients with Parkinsonian syndromes in the United States and Western Europe. The increased uptake of MET, FET and FDOPA in gliomas and brain metastases appears to be caused predominantly by increased transport via the amino acid transport system L for large neutral amino acids namely the subtypes LAT1 and LAT2.