68Ga-PSMA-11 PET/mpMRI for local detection of primary prostate cancer in men with a negative prior biopsy

Introduction and objective Multiparametric MRI (mpMRl) represents the current gold standard for the detection of primary prostate cancer (PC) after a negative biopsy. PSMA PET imaging has been introduced in the diagnostic work-up of PC with high accuracy, but is currently mainly utilised in the setting of biochemical recurrence. This study aimed to determine the efficacy of combined Ga-68-PSMA-11 PET/mpMRI imaging to detect PC in patients with previously negative prostate biopsies. Methods A total of 57 patients who had undergone at least one prior negative prostate biopsy were included in this retrospective analysis. All patients underwent Ga-68-PSMA-11 PET/mpMRI imaging of the prostate. mpMRI was evaluated according to the PIRADS classification system and Ga-68-PSMA-11 PET was rated on a 5-point Likert scale (1: PC highly unlikely; 2: PC unlikely; 3: presence of PC is equivocal; 4: PC likely; 5: PC highly likely). All patients received a systematic random biopsy as well as a targeted transrectal biopsy of lesions suspicious on imaging. Imaging and histological biopsy outcomes were compared on a per-patient basis. Results In the histological analysis, 35/57 (61.4%) patients harboured PC lesions. In patients with biopsy-proven PC, 21/35 (60.0%) had a PI-RADS 4 or 5 lesion on mpMRI and 28/35 (80.0%) had a PET rating of 4 or 5. Combined (68)GaPSMA-11 PET/mpMRT missed only one patient with a Gleason score (GS) 7a tumour (rating of 1 or 2 in both PET and mpMRI). Limitations include the retrospective analysis as well as possible false negative biopsy results even in a fusion biopsy setting. Conclusion In this initial analysis, the combined (68)GaPSMA-11 PET/mpMRI proved to be a valuable imaging tool to guide prostate biopsies for the detection of PC in patients with a negative prior biopsy. In this approach, (68)GaPSMA-11 PET and mpMRI show partially complementary findings that enhance the detection of PC lesions.

Automated summary

Multiparametric MRI (mpMRI) is the gold standard for detecting primary prostate cancer (PC) after a negative biopsy, while PSMA PET imaging is utilized mainly for biochemical recurrence. The study demonstrated that combined Ga-68-PSMA-11 PET/mpMRI imaging is effective in detecting PC in patients with previously negative prostate biopsies. The results showed that the combined imaging technique is valuable in guiding prostate biopsies for the detection of PC lesions.