The Influence of Specific Activity on the Biodistribution of 18F-rhPSMA-7.3: A Retrospective Analysis of Clinical PET Data

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Langbein T., Wurzer A., Gafita A., Robertson A., Wang H., Arçay A., ...More

Journal of Nuclear Medicine, vol.63, no.5, pp.742-745, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 63 Issue: 5
  • Publication Date: 2022
  • Doi Number: 10.2967/jnumed.121.262471
  • Journal Name: Journal of Nuclear Medicine
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, EMBASE, MEDLINE, Veterinary Science Database
  • Page Numbers: pp.742-745
  • Keywords: 18F, Biodistribution, molar activity, PET/CT, PSMA
  • Akdeniz University Affiliated: No


© 2022 by the Society of Nuclear Medicine and Molecular Imaging.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 obtained with a high specific activity (median, 178.9MBq/μg; n=42) and a low specific activity (median, 19.3MBq/ μg; n=42) was 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 onlyminor 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-FDG.