Abstract
Prostate specific membrane antigen (PSMA) is highly overexpressed in prostate cancer. Many PSMA analogue radiotracers for PET/CT imaging of prostate cancer staging have been developed such as 68Ga-PSMA-11. This radiotracer has achieved good results in multiple clinical trials, but because of superior imaging characteristics of 18F-fluoride, 18F-PSMA-11 was developed. The aim of this study was to evaluate the safety of administration and the radiation dosimetry of 18F-PSMA-11. METHODS: Six patients (age 62-68y, mean 66 ± 2y) with suspected prostate cancer recurrence after previous treatment were administered 2 MBq/kg bodyweight 18F-PSMA-11 followed by PET/CTlow-dose imaging at 0, 20, 50, 90 and 300 min post injection (p.i.). To evaluate the safety of administration, vital parameters were monitored. To assess toxicity, full blood count and biochemical parameters were determined. According to the latest ICRP recommendations, radiation dosimetry analysis was performed using IDAC-Dose 2.1. For blood activity measurement, small samples of venous blood were collected at various timepoints p.i. The unbound 18F-fluoride fraction was determined in plasma 20, 50 and 90 min after administration to evaluate the defluorination rate of 18F-PSMA-11. RESULTS: After injection, 18F-PSMA-11 was rapidly cleared from the blood. 29.0 ± 5.9% of the activity was excreted in urine at 5h p.i. The free 18F fraction in plasma increased from 9.7 ± 1.0% 20 min p.i. to 22.2 ± 1.5% 90 min p.i. The highest tracer uptake was observed in kidneys, bladder, spleen and liver. No study drug related adverse events were observed. The calculated mean effective dose was 12.8 ± 0.6 µSv/MBq. CONCLUSION: 18F-PSMA-11 can be safely administered and results in a mean effective dose of 12.8 ± 0.6 µSv/MBq. Therefore, the total radiation dose is lower compared to other PSMA PET agents and in the same range of 18F-DCFPyL.
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.