@article {Langbeinjnumed.121.262471, author = {Thomas Langbein and Alexander Wurzer and Andrei Gafita and Andrew Robertson and Hui Wang and Ayca Arcay and Michael Herz and Hans-Juergen Wester and Wolfgang Andreas Weber and Matthias Eiber}, title = {The Influence of Specific Activity on the Biodistribution of 18F-rhPSMA-7.3: A Retrospective Analysis of Clinical Positron Emission Tomography Data}, elocation-id = {jnumed.121.262471}, year = {2021}, doi = {10.2967/jnumed.121.262471}, publisher = {Society of Nuclear Medicine}, 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/{\textmu}g, n = 42) and a low specific activity (median = 19.3MBq/{\textmu}g, n = 42) were compared. Results: Tracer uptake by the parotid gland, submandibular gland and spleen was moderately, but significantly lower in the {\textquotedblleft}low specific activity{\textquotedblright} group than in the {\textquotedblleft}high specific activity{\textquotedblright} 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.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/early/2021/08/12/jnumed.121.262471}, eprint = {https://jnm.snmjournals.org/content/early/2021/08/12/jnumed.121.262471.full.pdf}, journal = {Journal of Nuclear Medicine} }