Radiolabeling and PET/CT Imaging Protocols

Radiolabeling and administration of ⁶⁸Ga-PSMA-11 and 18F-PSMA-1007 were performed according to previously reported radiosynthesis and administration procedures [16 (link),17 (link)]. Immediately after injection of the tracer, 20 mg of furosemide was administered intravenously. Patients were asked to empty the bladder prior to the scan. PET/CT scans were acquired 60 min after tracer injection using an iodine-containing contrast agent (Ultravist 300, Bayer Pharma AG, Berlin, Germany; or Imeron 300, Bracco, Konstanz; Germany 2.5 mL/s) during the portal venous phase. For reconstruction, the TrueX algorithm (3 iterations, 21 subsets; Biograph 64, Siemens Healthineers, Erlangen, Germany) or the VUE Point FX algorithm (2 iterations, 36 subsets; Discovery 690) was used with an axial 168 x 168 matrix. Phantom studies based on the National Electrical Manufacturers Association NU2-2001 standard were conducted to allow valid pooling of results between different scanners. Mean injected activity was 213.1 ± 49.7 MBq in pre- and 212.6 ± 45.1 MBq in post-therapeutic PET.