Optimization of the radiosynthesis of [68Ga]Ga-PSMA-11 using a Trasis MiniAiO synthesizer: do we need to heat and purify?

Introdution: [ 68 Ga]Ga-prostate specific membrane antigen (PSMA)-11 showed a clear gain in sensitivity for lesion detection in the biological recurrence of prostate cancer as compared to the standard [ 18 F]fluorocholine radiopharmaceutical. To meet the strong demand for [ 68 Ga]Ga-PSMA-11, we aimed to optimize an automated radiolabeling process by evaluating the influence of different key parameters on radiochemical purity and radiochemical yield. Methods: The radiosynthesis of [ 68 Ga]Ga PSMA-11 was performed using a Trasis MiniAio synthesizer and a 68 Ge/ 68 Ga GalliaPharm generator supplied by Eckert & Ziegler, Berlin, Germany. Optimized labeling parameters were evaluated by variation of sodium acetate concentrations and temperature of radiolabeling as well as the purification process. Results: For each condition tested, radiochemical purity was higher than 99% in the final vial without batch failure, indicating a robust and fast radiosynthesis process. Radiosynthesis without the solid phase extraction purification process at room temperature in less than 5 min resulted in a radiolabeling efficiency of over 99% and remained stable at least 4 h without manual processing to limit operator radiation exposure. Conclusion: The procedure was completely automated and provided a high radiochemical yield. It can be performed several times a day, facilitating the clinical demand of this radiopharmaceutical.