MP13-15 68GA-PSMA-11 PET/MPMRI FOR DETECTION OF PRIMARY PROSTATE CANCER IN PREVIOUSLY NEGATIVE-BIOPSIED MEN

Abstract

INTRODUCTION AND OBJECTIVE: Multiparametric MRI (mpMRI) represents the current gold standard for detection of primary prostate cancer (PCa) after negative biopsy. PSMA PET imaging has been introduced in the diagnostic work-up of PCa with high specificity, currently mainly utilized in biochemical recurrence. Therefore, the aim of this investigation was to determine the efficacy of combined 68Ga-PSMA-11 PET/mpMRI imaging to detect PCa in patients with previously negative prostate biopsy. METHODS: 57 patients (pts.) who underwent at least one prior negative prostate biopsy were included in this analysis. All pts. underwent 68Ga-PSMA-11 PET/mpMRI imaging of the prostate. Lesions on mpMRI were evaluated according to the PI-RADS classification system and lesions on 68Ga-PSMA-11 PET were rated according to a 5-point scale on a sextant basis (1: PCa highly unlikely; 2: PCa unlikely; 3: presence of PCa is equivocal; 4: PCa likely; 5: PCa highly likely). All pts. received a systematic random biopsy as well as a targeted transrectal biopsy of lesions suspicious on imaging. Results of imaging and histological analysis of prostate biopsies were compared per patient and per prostate sextant. RESULTS: On histological analysis 35/57 (61.4%) of pts. and 75/342 (21.9%) of sextants showed PCa lesions. In patients with biopsy confirmed PCa 21/35 (60.0%) showed a PI-RADS 4 or 5 lesion on mpMRI and 28/35 (80.0%) presented with a PET rating of 4 or 5. 20/75 (26.7%) of sextants with histological confirmed PCa showed a PI-RADS 4 or 5 lesion on mpMRI and 26/75 (34.7%) of sextants presented with a PET rating of 4 or 5. Combined 68Ga-PSMA-11 PET/mpMRI missed only one patient with a Gleason-Score (GS) 7a tumor (rating of 1 or 2 in both, PET and mpMRI). Limitations represent the retrospective analysis as well as possible false negative biopsy results even in a fusion biopsy setting. CONCLUSIONS: In this initial analysis, 68Ga-PSMA-11 PET/mpMRI proved to be a valuable imaging tool to guide prostate biopsies for detection of PCa in patients after prior negative biopsy. Hereby, 68Ga-PSMA-11 PET and mpMRI show complementary findings thus increasing detection of PCa lesions. Source of Funding: none