Synthesis of fluorine-18-labelled TSPO ligands for imaging neuroinflammation with Positron Emission Tomography

Fluorine-18 radiochemistry is an essential tool in Positron Emission Tomography, providing the bridge between the cyclotron-produced raw radioisotope and the biomedical image of an in vivo radioactivity distribution. From the fluorine-18 labelled radioligands for the translocator protein 18 kDa that are produced in our laboratory, namely [18F]FEDAA1106, 6-[18F]F-PBR28, [18F]PBR111 and [18F]DPA-714, we address various aspects of fluorine-18 radiochemistry, such as rationales of radiotracer design, radioisotope production and [18F]fluoride activation, and procedures of radiofluorination, purification and formulation. Automation of the radiochemistry process has become indispensable in order to assure a constant radiopharmaceutical quality and reproducible radiochemical yields as well as to meet the required radiation protection aspects.