Detection and Local Staging of Prostate Cancer by 68Ga-PSMA-PET/CT, Comparison with mpMRI and Histopathology

Abstract

Introduction: 68Ga-PSMA-PET/CT has proven its value in prostate cancer with high positive predictive value for lymph node metastasis and superior detection of distant metastasis. There is growing evidence that 68Ga-PSMA- PET/CT has high sensitivity for detection of tumor lesions in the prostate as well. Studies thus far have mainly been performed in patients prior to prostatectomy. Aim of this study is to evaluate diagnostic accuracy in a mixed population of men with increased risk of prostate cancer and evaluate diagnostic possibilities with respect to extra-capsular extension and seminal vesicle invasion. Methods: The population consisted of a retrospectively included sequential cohort of 69 patients with 68Ga-PSMA-PET/CT and mpMRI available. 68Ga-PSMA-PET/CT was re-evaluated by two readers blinded for mpMRI and clinical information. Likelihood of tumour presence, extra-prostatic extension and seminal vesicle invasion was scored on 5-point Likert scale and localized schematically. Results were compared with mpMRI. Available pathological outcome served as gold standard. SUVmax of index lesions was measured and correlated to index tumor Gleason grade. Results: Clinically significant prostate cancer (Gleason ≥ 3 + 4) was detected in 57 (83%) of 69 patients. Diagnostic accuracy was 89% for PET reader 1, 93% for PET reader 2 and 86% for mpMRI. Lesion concordance of 68Ga-PSMA-PET/CT and mpMRI was 97%. SUVmax of the index lesion correlated to Gleason grade. Sensitivity for extracapsular extension in the prostatectomy group was 62% for PET reader 1, 33% for PET reader 2 and 50% for mpMRI. Specificity was 62% for PET reader 1, 100% for PET reader 2 and 69% for mpMRI. Conclusion: Ga68-PSMA-PET shows high accuracy in the detection of tumor lesions in the prostate. Results on evaluating extra-capsular extension and seminal vesicle invasion are comparable to mpMRI. This study adds to the increasing evidence that 68Ga-PSMA-PET/CT is imperative in detection of prostate cancer prior to biopsy.