SLC6A3 and Dyskinesia: In both the bilateral putamen and the head of the caudate nucleus, the uptake ratio index (URI) of [11C]2β-carbomethoxy-3β-(4-fluorophenyl) tropane ([11C]CFT), a marker for presynaptic dopamine transporter (DAT), in the bilateral putamen was significantly lower in the drug-naïve patients and patients with dyskinesia than in the normal controls (Table 3).