K S Morrison | PubMed Health

PubMed1992

Plasma L-[18F]6-fluorodopa input function: a simplified method.

This article describes a simplified method for the determination of the L-[18F]6-fluorodopa (FDOPA) fraction time course that takes advantage of the strong correlation between the radioactivity ratio (metabolites/FDOPA) and time. Serial arterial blood samples are collected for assay of plasma total radioactivities following an intravenous injection of FDOPA into carbidopapretreated subjects. In addition, a single plasma sample, collected late in the study and analyzed for FDOPA fraction, is sufficient to determine accurately the time course of the FDOPA concentration in plasma. The validated straight-line method greatly simplifies blood analysis for routine positron emission tomography FDOPA studies.

Dihydroxyphenylalanine↗

PubMed1991

The reproducibility of striatal uptake data obtained with positron emission tomography and fluorine-18-L-6-fluorodopa tracer in non-human primates.

Cynomolgus and rhesus monkeys have been studied via PET with [18F]-L-6 fluorodopa tracer. Striatal fluorodopa uptake rate constants have been derived by graphical analysis of transaxial slice images centered on the striata. The differences between pairs of values of the rate constant, obtained from two scans on the same monkey separated by two weeks or more, exhibited a relative standard deviation of 34.4%. If the two scans were conducted one immediately after the other, with the position of the monkey undisturbed, the standard deviation was reduced to 14.0%. The utility of this technique was demonstrated by comparing the effects on the scans of halothane and pentobarbital anesthesia and by the administration of NSD 1015, a peripheral and central inhibitor of L-aromatic amino-acid decarboxylase, between back-to-back scans. With NSD 1015, the fluorodopa uptake constant was reduced by an average of 76.0%.

Animals↗