Purpose: Multiparametric magnetic resonance imaging (mpMRI) fails to identify some men with significant prostate cancer. Prostate-specific membrane antigen positron emission tomography/computerized tomography (PSMA PET/CT) is recommended for staging of prostate cancer, but its additional benefit above mpMRI alone in local evaluation for prostate cancer is unclear. The study aim was to evaluate the ability of mpMRI and PSMA PET/CT individually and in combination, to predict tumor location and Gleason score ≥3+4 on robot-assisted laparoscopic radical prostatectomy (RALP) histology.
Materials and methods: We retrospectively reviewed 1,123 men with a preoperative mpMRI and 68Ga-PSMA PET/CT prior to a RALP. Tumor locations were collected from both imaging modalities and compared to totally embedded prostate histology. Lowest apparent diffusion coefficient value on mpMRI and the highest maximum standardized uptake value (SUVmax) on 68Ga-PSMA PET/CT were collected on the index lesions to perform analysis on detection rates.
Results: Median prostate specific antigen was 6. Median Gleason score on biopsy and RALP histology was 4+3. The index lesion and multifocal tumor detection were similar between mpMRI and 68Ga-PSMA PET/CT (p=0.10; p=0.11). When combining mpMRI and 68Ga-PSMA PET/CT, index Gleason score ≥3+4 cancer at RALP was identified in 92%. Only 10% of patients with Gleason score ≤3+4 on biopsy with an SUVmax <5 were upgraded to ≥4+3 on RALP histology, compared to 90% if the SUVmax was >11.
Conclusions: The addition of a diagnostic 68Ga-PSMA PET/CT to mpMRI can improve the detection of significant prostate cancer and improve the ability to identify men suitable for active surveillance.
Keywords: multiparametric magnetic resonance imaging; neoplasm staging; pathology, clinical; prostatectomy; prostatic neoplasms.