The effect of aromatic fluorine substitution in l-DOPA on the in vivo behaviour of [18F]2-, [18F]5- and [18F]6-fluoro-l-DOPA in the human brain

Remarkable differences in the human in vivo behaviour of each of the three [18F]-labelled ring fluorinated isomers of l-dihydroxyphenylalanine (l-DOPA) are presented. Unlike [18F]2-fluoro-l-DOPA, which did not appear to cross the blood brain barrier, [18F]5-fluoro-l-DOPA appears to be taken up and cleared from the cerebellum and the striata. In contrast with the 2- and 5-fluoro isomers of l-DOPA, radioactivity derived after injection of [18F]6-fluoro-l-DOPA is specifically retained in the striata. The present study is the first direct comparison of the time course and distribution of radioactivity in the human brain after intravenous injections of [18F]2-, [18F]5- and [18F]6-fluoro-l-DOPA.