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

Abstract

Fluorine-18 labeled fluorodopamine (FDA) was synthesized by the direct fluorination with [ 18F]F 2 [produced by the nuclear reaction 18O(p,n) 18F] of dopamine in anhydrous hydrogen fluoride containing boron trifluoride at −65 °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]F 2, was 10 ± 2% at the end of the 120-min synthesis from E0B1. 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 μg/kg/min) is considerably lower than therapeutic doses (2–10 μg/kg/min) of dopamine.