Purpose
Multiparametric MRI (mpMRI) fails to identify some men with significant prostate cancer. 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 tumour location and Gleason score ≥3+4 on robot assisted laparoscopic radical prostatectomy (RALP) histology.
Materials and Methods
A retrospective review of 1123 men with a pre-operative mpMRI and 68Ga-PSMA PET/CT prior to a RALP. Tumour locations were collected from both imaging modalities and compared to totally embedded prostate histology. Lowest apparent diffusion coefficient (ADC) value on mpMRI and the highest maximum standardised uptake value (SUVmax) on 68Ga-PSMA PET/CT were collected on the index lesions to perform analysis on detection rates.
Results
Median PSA was 6. Median Gleason score on biopsy and RALP histology was 4+3. The index lesion and multifocal tumour 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.