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Previous positron emission tomography (PET) studies with levodopa analogs have revealed a modestly increased capacity for dopamine synthesis in the striatum of patients with schizophrenia compared with healthy age-matched control subjects. We hypothesized that not just the synthesis but also the turnover of radiolabeled dopamine is elevated in patients. To(More)
Molecular and functional imaging techniques reveal evidence for lateralization of human cerebral function. Based on animal data, we hypothesized that asymmetry in dopamine neurotransmission declines during normal aging. In order to test this hypothesis, we measured dopamine D2/3 receptor availability with [18F]desmethoxyfallypride-PET (DMFP) in putamen and(More)
Dopamine neurotransmission influences those cognitive processes, which are generally regarded as prefrontal cortical functions. In previous positron-emission-tomography (PET) studies, net blood-brain clearance of [18F]-fluoro-l-DOPA (FDOPA) correlated with impaired cognitive performance in patients with Parkinson's disease or schizophrenia. We hypothesized(More)
Dopamine transmission remains central to our understanding of neurocircuitry models of schizophrenia, and to the mechanism of action of typical antipsychotic medications, which preferentially block D (2)-receptors in striatum. In cerebral cortex, D (2)- and D (1)- mediated transmission modulates information processing, and tunes the activity of the(More)
The high-affinity radioligand [(18)F]fallypride (FP) is frequently used for quantification of striatal/extrastriatal D(2/3) receptors and the receptor occupancies of antipsychotics (APs). Its 110 minutes half-life allows long scan durations. However, the optimum scan duration is a matter of debate. This investigation focuses on scan-duration-related effects(More)
Molecular imaging methods such as positron emission tomography (PET) are increasingly involved in the development of new drugs. Using radioactive tracers as imaging probes, PET allows the determination of the pharmacokinetic and pharmacodynamic properties of a drug candidate, via recording target engagement, the pattern of distribution, and metabolism.(More)
OBJECTIVE Aripiprazole at clinically effective doses occupies some 90% of striatal dopamine 2 and 3 (D(2)/D(3)) receptors. In order to further characterize its extrastriatal and time-dependent binding characteristics, the authors conducted positron emission tomography (PET) studies with the D(2)/D(3) antagonist [(18)F]fallypride at varying time points after(More)
UNLABELLED Substituted benzamides such as (11)C-raclopride or (123)I-iodobenzamide are selective radiotracers for PET and SPECT imaging of D(2)-like dopamine (DA) receptors. (18)F-Desmethoxyfallypride ((18)F-DMFP) is a benzamide tracer with the advantage of an (18)F label. We optimized the synthesis and evaluated (18)F-DMFP in PET studies on healthy human(More)
UNLABELLED (11)C-Raclopride has been widely used for PET studies of dopamine D(2/3) receptors in human brain. The long half-life of (18)F may impart advantages to the novel moderate-affinity benzamide (18)F-desmethoxyfallypride and its high-affinity congener (18)F-fallypride for competition studies and for detection of extrastriatal binding. However, the in(More)
The 'atypicality' of the antipsychotic drug, amisulpride, has been attributed to preferential extrastriatal binding. Previous investigations of striatal D2 receptor occupancy by amisulpride revealed conflicting results. The aim of this PET study was to measure the striatal occupancy by amisulpride and to correlate it with the corresponding drug plasma(More)