Dual-time-point dynamic ⁶⁸Ga-PSMA-11 PET/CT for parametric imaging generation in prostate cancer

To investigate the optimal dual-time-point (DTP) approaches using dynamic ⁶⁸Ga-PSMA-11 PET/CT imaging to generate parametric images for prostate cancer patients.

Fifteen patients with prostate cancer were intravenously administered ⁶⁸Ga-PSMA-11 of 181.9 ± 47.2 MBq, followed by an immediate 60 min dynamic PET/CT scan. List-mode data were reconstructed into 25 timeframes (6 × 10 s, 8 × 30 s, and 11 × 300 s) and corrected for motion and partial volume effect. DTP parametric images were generated using different interval time points of 5 min and 10 min, with a minimum of 30 min time interval. Net influx rates (K_i) were calculated through the fitting of a single irreversible two-tissue compartmental model. Intraclass correlation coefficient (ICC) values between DTP protocols and 60 min K_i were obtained. Lesion-to-background ratios (LBRs) of K_i and standardized uptake value (SUV) images in each DTP protocol were determined.

The DTP protocol of 5-10 min with a 40-45 min interval showed the highest ICC of 0.988 compared with the 60 min K_i, whereas the ICC values for the intervals of 0-5 min with 55-60 min and 0-10 min with 50-60 min were 0.941. The LBRs of the 60 min K_i, 5-10 min with 40-45 min K_i, 0-5 min with 55-60 min K_i, 0-10 min with 50-60 min K_i, SUV_mean, and SUV_max images were 29.53 ± 27.33, 13.05 ± 15.28, 45.15 ± 53.11, 45.52 ± 70.31, 19.77 ± 23.43, and 25.06 ± 30.07, respectively.

The 0-5 min with 55-60 min DTP parametric imaging exhibits a comparable K_i to 60 min parametric imaging and remarkable image quality and contrast than SUV imaging, enhancing prostate cancer diagnosis while maintaining time efficiency.