[ 18 F]FDOPA and [ 18 F]CFT are both sensitive PET markers to detect presynaptic dopaminergic hypofunction in early Parkinson's disease

The aim of this study was to compare two PET ligands, 6‐[ 18 F]fluoro‐ L ‐dopa ([ 18 F]FDOPA) and 18 F‐labeled CFT, 2β‐carbomethoxy‐3β‐(4‐[ 18 F]‐fluorophenyl)tropane ([ 18 F]CFT), in detecting presynaptic dopaminergic hypofunction in early Parkinson's disease (PD). These ligands reflect different aspects of presynaptic dopaminergic function, since [ 18 F]FDOPA mainly reflects 6‐[ 18 F]fluorodopamine (fluorodopamine) synthesis and storage whereas [ 18 F]CFT uptake is related to dopamine transporter function. Eight de novo patients with PD who had never been on antiparkinsonian medication were investigated with [ 18 F]FDOPA and [ 18 F]CFT PET. Five healthy volunteers were studied as controls. In PD patients, both [ 18 F]FDOPA and [ 18 F]CFT uptakes were significantly reduced both in the contralateral and ipsilateral anterior and posterior putamen. The reduction was greatest in the contralateral posterior putamen (to 28% of control mean for [ 18 F]FDOPA, P < 0.0001 and to 16% for [ 18 F]CFT, P < 0.0001). Individually, all patients' [ 18 F]FDOPA and [ 18 F]CFT uptake values in the contralateral anterior and posterior putamen were below 3 SD of the control mean. In the caudate nucleus, the mean uptake of both tracers was significantly reduced both ipsilaterally and contralaterally, but less severely than in the putamen (to 69% of the control mean for [ 18 F]FDOPA, P = 0.003 and to 60% for [ 18 F]CFT, P = 0.001 contralaterally). Our results show that both [ 18 F]FDOPA as well as [ 18 F]CFT sensitively detect presynaptic dopaminergic hypofunction in early PD. They demonstrate a considerable reduction of tracer uptake that is greatest in the posterior putamen, followed by the anterior putamen and the caudate nucleus. Synapse 40:193–200, 2001. © 2001 Wiley‐Liss, Inc.