J Nucl Med. 2021 Aug 12:jnumed.121.262471. doi: 10.2967/jnumed.121.262471. Online ahead of print.
ABSTRACT
We investigated whether the time between synthesis and injection and the resulting decrease in specific activity affects the normal organ and tumor uptake of the PSMA ligand, 18F-rhPSMA-7.3, in patients with prostate cancer. Methods: The biodistribution of 18F-rhPSMA-7.3 on PET/CT scans performed with a high specific activity (median = 178.9MBq/µg, n = 42) and a low specific activity (median = 19.3MBq/µg, n = 42) were compared. Results: Tracer uptake by the parotid gland, submandibular gland and spleen was moderately, but significantly lower in the “low specific activity” group than in the “high specific activity” group (median SUVmean 16.7 vs. 19.2; 18.1 vs. 22.3, and 7.8 vs. 9.6, respectively). No other statistically significant differences were found for normal organs or tumor lesions. Conclusion: A 10-fold decrease in specific activity has only minor effects on the biodistribution of 18F-rhPSMA-7.3. These findings suggest that 18F-labeled PSMA ligands can be centrally produced and shipped to PET clinics in a similar way to 18F-fluorodeoxyglucose.
PMID:34385338 | DOI:10.2967/jnumed.121.262471
