Tropane derivative studies ([11C] CFT and [123I] β-CIT) have shown a direct correlation between decreased DAT in the putamen and PD symptoms.13,44 Descriptions of the characteristics of several DAT tracers, including time to reach tracer equilibrium (scan time); tracer maximum accumulation (peak striatal activity); differential contrast imaging in the striatal area and the rest of the brain, especially in the cerebellum (signal to noise ratio); and affinity competition inhibition of serotonin and dopamine transporters (SERT: DAT) are given in Table 1. This evidence concerns the gene SLC6A3 and Parkinson disease.