MP77-12 ⁶⁸ GA-PSMA PET/CT VERSUS MPMRI FOR LOCOREGIONAL PROSTATE CANCER STAGING: CORRELATION WITH FINAL HISTOPATHOLOGY

Abstract

INTRODUCTION AND OBJECTIVES: Current standard of care for prostate cancer detection is multiparametric MRI (mpMRI) and biopsy prior to active treatment. In recent years, prostate-specific membrane antigen (PSMA) ligands have been used in positron emission tomography (PET) to target prostate cancer cells for detection, however guidelines on its use are limited by its infancy. PSMA PET is a highly sensitive and specific scan that has been primarily used in detecting prostate cancer recurrence. PSMA PET may be combined with computed tomography (CT) or MRI, although few centres have access to PET/MRI machines. There is a growing role for PSMA PET/CT in primary staging. We aimed to examine how PSMA PET/CT could contribute to current standards of care by comparing mpMRI and PSMA PET/CT to prostatectomy histopathology.METHODS: We conducted a chart review from February 2015 to January 2017 of 50 male patients staged for prostate cancer using PSMA PET/CT and mpMRI who then underwent radical prostatectomy. Pre-operative PSMA PET/CT and mpMRI were paired with their corresponding histological tumor.RESULTS: A total of 50 male patients were included in this study, with a mean age of 64.9 years (AE 5.6), and PSA of 10.6 (AE 8.1). The median time between PSMA PET/CT and surgery was 5 weeks (range 0-21 weeks), and the median time between mpMRI and surgery was 18 weeks (IQR 13-25 weeks). The median time between mpMRI and PSMA PET/CT was 12 weeks (IQR 3-12.25 weeks). A total of 81 lesions were confirmed by histopathology. Fifty index lesions were confirmed by histopathology, all of which were detected by PSMA PET/ CT and 47 by mpMRI (100% vs. 94%). Thirty-one secondary lesions were confirmed by histopathology, 29 of which were detected by PSMA PET/CT and 16 by mpMRI (93.5% vs. 51.6%). PSMA had better sensitivity for index lesion localization than mpMRI (81.1% vs. 64.8%). Specificity was similar for PSMA PET/CT and mpMRI (84.6% vs. 82.7%). Forty-five patients (90%) were found to have multifocal disease on histopathology. PSMA predicted multifocal disease in 43 (86%) of patients (88.9% sensitivity, 40.0% specificity); mpMRI predicted multifocal disease poorly (10% sensitivity, 10% specificity).CONCLUSIONS: PSMA-PET/CT provided superior detection of prostate cancer lesions with better sensitivity than mpMRI. PSMA-PET/ CT can be used to enhance locoregional mpMRI to provide improved detection and characterization of lesions.

Diagnostic performance of 68Ga-PSMA-11 PET/MRI-guided biopsy in patients with suspected prostate cancer: a prospective single-center study

“…Positron emission tomography (PET)/MRI targeting prostate-specific membrane antigen (PSMA) could be an ideal technique to improve the accuracy of imaging-guided biopsies, combining the high sensitivity and specificity of PSMA-PET for PCa with the high anatomical contrast and spatial resolution of MRI [ 13 – 15 ]. Despite promising results in PSMA-PET/computed tomography (CT) for biopsy targeting [ 16 ], with an accuracy of 80.6% for sigPCa [ 17 ], the diagnostic accuracy of PSMA-PET/MRI-guided biopsy has not yet been prospectively assessed.…”