Dopamine transporter positron emission tomography (PET) is now popularly used in clinics to visualize the integrity of presynaptic dopaminergic nerve terminals, and a quantitation of striatal binding in PET images is important for detecting preclinical stage, monitoring disease progression, and evaluating responses to disease modifying treatment in Parkinson’s disease (PD) [1]. This evidence concerns the gene SLC6A3 and Parkinson disease.