Comparison of early and standard ¹⁸F-PSMA-11 PET/CT imaging in treatment-naïve patients with prostate cancer

To evaluate the diagnostic performance of dual-time-point ¹⁸F-PSMA-11 PET/CT imaging at 30 and 60 min post-injection (p.i.) in treatment-naïve patients with prostate cancer (PCa).

Twenty treatment-naïve patients with histology-proven PCa who underwent ¹⁸F-PSMA-11 PET/CT scans at both 30 and 60-min p.i. were retrospectively analyzed. Lesion detection, semi-quantitative analysis of lesion and background, and unspecific bone uptake (UBU) between two time points were evaluated and compared. Besides, interrater reliability was also evaluated.

Lesion detection was consistent at both 30 and 60-min p.i. imaging of 20 patients (mean age 72 ± 9), identifying 27 primary prostate lesions, 84 lymph node metastases, bone metastases in 8 patients, and other metastases in 2 patients. Primary prostate lesions showed no significant difference in SUVmax and target-to-blood pool (T/B) ratios between the two imaging times, while these parameters significantly increased over time in bone metastases. Lymph node metastases showed no significant difference in SUVmax but higher T/B ratios at 60 min compared to 30 min. A higher frequency of UBU was observed at 60 min (37.3%) compared to 30 min (32.3%), with significantly higher SUVmax and T/B ratios at 60 min. 85.6% UBU was categorized as PSMA-RADS 2 at 60 min, and the others were PSMA-RADS 3 or 4. The most frequent localization was vertebrae, followed by ribs. Interrater reliability was almost perfect for lesion detection at both time points.

Early 30-min ¹⁸F-PSMA-11 PET/CT imaging provided comparable PCa lesion detection and semi-quantitative analysis with reduced UBU to the standard 60-min imaging.