18F-labeling of the nitroimidazole nucleoside analogue 1-(5-fluoro-5-deoxy-α-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 °C within 5 min using 5 mg of precursor. Hydrolysis was best performed with 1 mL of 0.1 N NaOH at 20 °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 μA, 60 min). Thus, a convenient approach suitable for large-scale production of [18F]FAZA was developed by an automated process.

[11C]Choline has been under investigation as a PET ligand for imaging tumor tissue, especially prostate cancer. An improved, automated synthesis of the tracer now was established. [11C] Choline was produced by labeling 2-(dimethylamino)-ethanol (DMAE) with [11C]CH3I in a Tefzel® tube at room temperature without solvent. The product was purified using a cation exchange cartridge. Reaction conditions were optimized with respect to synthesis time and amount of DMAE, resulting in radiochemical yields higher than 80% using 60μl of DMAE in 20min, radiochemical purity was >99% and residual DMAE was below 10ppm. After 11C-production of 1h at 50μA [11C]choline activities of 30.0±5.6 GBq (n=29) were obtained in sterile solution ready for intravenous administration.