Direct radiofluorination of dopamine: 18F-labeled 6-fluorodopamine for imaging cardiac sympathetic innervation in humans using positron emission tomography.

Fluorine-18 labeled fluorodopamine (FDA) was synthesized by the direct fluorination with [18F]F2 [produced by the nuclear reaction 18O(p,n)18F] of dopamine in anhydrous hydrogen fluoride containing boron trifluoride at -65 degrees C. Reverse-phase high-performance liquid chromatography (HPLC) was used to separate [18F]6-FDA from the reaction mixture containing 18F-labeled 2- and 5-FDA. The radiochemical yield of [18F]6-FDA, with respect to [18F]F2, was 10 +/- 2% at the end of the 120-min synthesis from EOB1. The specific activity of [18F]6-FDA at the end of synthesis, 10 +/- 1.5 Ci/mmol, is sufficiently high that the amount of 6-FDA associated with the infusion of a dose of 5 mCi of [18F]6-FDA over 3 min into a 50-kg human (0.5-0.7 microgram/kg/min) is considerably lower than therapeutic doses (2-10 micrograms/kg/min) of dopamine.