F-DOPA (6[18F]-dihydroxyphenylanine) is a false neurotansmitter analog of L-DOPA. Its decarboxylated product, 6-[18F]-Dopamine accumulates in nerve endings permitting the in vivo visualization and relative quantification of dopamine and its metabolites in nerve endings in adults by PET. Using F-DOPA together with pretracer administration of carbidopa and post-tracer administration of an infusion of LNAA (large neutral amino acids) a new method was previously established that would allow PET study of children by minimizing ionizing radiation exposure, eliminating the requirement of arterial catherization, and allowing for a minimum time in the scanner and sedation of subjects with propofol when necessary. Using this method to study Tourette's Syndrome, two regions, the left caudate (25%) and right midbrain (53%), were found to have an abnormally high F-DOPA accumulation that was associated with tic severity. In a study of ADHD, accumulation of F-DOPA in the right midbrain was 48% higher than normal and correlated with symptom severity. No other dopamine-rich regions significantly differed between groups. These findings provide evidence of dopaminergic dysfunction at the level of the dopaminergic nuclei in ADHD children, and in the basal ganglia in Tourette's Syndrome. The regional cerebral glucose metabolic rates of clozapine-treated and fluphenazine-treated women with schizophrenia and normal controls were obtained by positron emission tomography using [18-F]-2-fluoro-2-deoxy-D-glucose (FDG) as the tracer. In women, as in previously studied men, both clozapine- and fluphenazine-treatment were associated with lower metabolism in the superior prefrontal cortex and higher metabolism in the medial temporal lobe. The greatest differences between the sexes were in the cingulate and striatum. In women, cingulate metabolic rates were reduced by 9.1% and 11.4% on clozapine and fluphenazine, respectively, whereas men have a statistically non-significant reduction of 0.1% with clozapine and a 3.2% increase with fluphenazine. In men, fluphenazine was associated with a much greater elevation in basal ganglia metabolic rates than was clozapine, 23.5 % compared to 3.75%, whereas in women, basal ganglia metabolic rates are nearly equally increased by fluphenazine (21.6%) and clozapine (15.1%).
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