Dose-reduced [18F]PSMA-1007 PET is feasible for functional imaging of the renal cortex

Background In Prostate-specific membrane antigen (PSMA) positron emission tomography with computed tomography (PET-CT), there is significant renal uptake. The standard in renal cortical functional imaging is scintigraphy with technetium-99m labeled dimercaptosuccinic acid (DMSA). Using [Ga-68]Ga-PSMA-11 PET for renal imaging has been suggested, but using [F-18]PSMA-1007 has not been explored. The aims of this study were to establish the optimal time point for renal imaging after [F-18]PSMA-1007 injection, to investigate the reproducibility of split renal uptake measurements, and to determine the margin for reduction in administered activity. Methods Twelve adult male patients with prostate cancer underwent [F-18]PSMA-1007 PET-CT at 8 time points up to 5.5 h post-injection (p.i.). List-mode data were binned to durations of 10 to 120 s per bed position (bp). Left renal percentage of total renal uptake (LRU%) was measured, and the difference between highest and lowest measurement per patient (delta max) was calculated. Images acquired at 1 h, 2 h, and 5.5 h p.i. with durations of 10 to 120 s/bp were rated regarding image quality. Results Imaging at 2 h p.i. with 60 s/bp yielded acceptable quality in all cases. Increasing acquisition time to 15 min for a single bp would allow reducing administered activity to 0.27 MBq/kg, resulting in an effective dose of 0.4 mSv for a 1-year old child weighing 10 kg. The median delta max of LRU% measurements was 2.7% (range 1.8-7.3%). Conclusions Renal [F-18]PSMA-1007 PET-CT is feasible, with imaging 2 h p.i., acceptable split renal uptake variability, and effective dose and acquisition time comparable to those of [Tc-99m]Tc-DMSA scintigraphy.

Automated summary

Renal [F-18]PSMA-1007 PET-CT with imaging at 2 hours post-injection provides acceptable image quality, consistent split renal uptake, and allows for reduction in administered activity. The study demonstrates feasibility of using [F-18]PSMA-1007 PET-CT for renal imaging and suggests potential for dose optimization.