Characterization of suspicious prostate lesions at multiparametric MRI with dynamic ⁶⁸ Ga-Gozetotide PET/CT

Prostate cancer (PCa) will affect approximately 12% of US men in their lifetime and remains the 2nd most common cause of cancer-specific death. However, there is a broad spectrum of severity of PCa; some require aggressive treatment and others can "watch-and-wait". Distinction of clinically significant prostate cancer (csPCa) from indolent PCA with current imaging methods remains challenging.

This study aims to evaluate dynamic prostate specific membrane antigen (PSMA) positron emission tomography (PET/CT) in the characterization of suspicious prostate lesions identified on multiparametric MRI (mpMRI).

Prospective study of biopsy-naïve patients with at least one Prostate Imaging and Reporting Data System (PI-RADS) score 5 or one PI-RADS score 4 plus a prostate specific antigen (PSA) ≥ 10 ng/mL. Dynamic PET/CT was performed for 30 min after administration of ⁶⁸Ga Gozetide. Time activity curves (TAC; kBq/cc) of suspicious prostate lesions were generated. TAC logarithmic slope was calculated for each GG at 5-, 10-, 15-, and 30 min. Apparent diffusion coefficient (ADC) at mpMRI for each lesion was tabulated.

19 PI-RADS v2.1 ≥ 4 and 6 secondary PI-RADS v2.1 ≥ 3 lesions in 19 patients were analyzed: 4 (16.0%) grade group (GG) 0 (benign), 3 (12.0%) GG 1, 6 (24.0%) GG 2, 6 (24.0%) GG 3, and 6 (24.0%) GG ≥ 4. Significant differences in slope values were observed between clinically insignificant disease (GG 0/1) and GG 2 or higher as early as 5 min post-injection (p < 0.05). At 30 min, GG 1 had the lowest mean slope (- 0.18 ± 0.57) and GG ≥ 4 exhibited the highest mean slope (2.35 ± 2.03). Slope value/ADC ratio further improved discrimination between different GGs.

Dynamic ⁶⁸ Ga Gozetotide time activity curves could distinguish GG0/1 from GG3 and GG4/5 PCa. The addition of mpMRI characteristics could further distinguish GG2 from GG4/5. GG2 could not be distinguished from GG3, probably due to small sample size.

Dynamic ⁶⁸ Ga Gozetotide PET/CT imaging may offer enhanced discrimination of MRI-visible prostate cancer lesions and assist in management decisions. Study registered with the FDA (IND 144,177) and clinicaltrials.gov (NCT04179968).