Automated synthesis of n.c.a. [18F]FDOPA via nucleophilic aromatic substitution with [18F]fluoride.

An improved, automated synthesis of [(18)F]FDOPA including four synthetic steps (fluorination, reductive iodination, alkylation and hydrolysis) is reported with each step optimized individually. In a home-made automatic synthesizer, 9064+/-3076 MBq of [(18)F]FDOPA were produced within 120 min from EOB (n=5). Radiochemical purity and enantiomeric excess were both >or= 95%. Specific activity was ca. 50 GBq/micromol at EOS. This automatically operable synthesis is well suited for the multi-patient-dose routine production of n.c.a. [(18)F]FDOPA.

Preparation of the hypoxia imaging PET tracer [18F]FAZA: reaction parameters and automation.

18F-labeling of the nitroimidazole nucleoside analogue 1-(5-fluoro-5-deoxy-alpha-D-arabinofuranosyl)-2-nitroimidazole (FAZA) was developed to use this tracer in PET for detection of hypoxia. Parameters for labeling and hydrolysis were optimized with regard to amount of precursor, temperature and time. Labeling yields reached a maximum of 62+/-4% at 100 degrees C within 5 min using 5 mg of precursor. Hydrolysis was best performed with 1 mL of 0.1 N NaOH at 20 degrees C for 2 min. Transfer of these conditions to an automated synthesizer resulted in an overall radiochemical yield of 20.7+/-3.5%. Absolute yields at EOS were 9.8+/-2.3 GBq of [18F]FAZA ready for injection (n=21; 50 min after EOB; irradiation parameters: 35 microA, 60 min). Thus, a convenient approach suitable for large-scale production of [18F]FAZA was developed by an automated process.