68Ga-PSMA PET/CT Combined with PET/Ultrasound-Guided Prostate Biopsy Can Diagnose Clinically Significant Prostate Cancer in Men with Previous Negative Biopsy Results

Abstract

The purpose of this study was to investigate the feasibility and diagnostic efficacy of ⁶⁸Ga-prostate-specific membrane antigen (PSMA) PET/CT combined with PET/ultrasound-guided biopsy in the diagnosis of prostate cancer (PCa). Methods: In total, 31 patients with a previously negative prostate biopsy but persistent elevated serum prostate-specific antigen (PSA) were imaged with a ⁶⁸Ga-PSMA PET/CT ligand before undergoing repeat prostate biopsy. On the basis of the proposed Prostate Cancer Molecular Imaging Standardized Evaluation criteria, ⁶⁸Ga-PSMA PET/CT results were interpreted as negative (molecular-imaging-for-PSMA expression score [miPSMA-ES] of 0-1) or positive (miPSMA-ES of 2-3). All patients underwent standard template systematic biopsy with up to 4 additional PET/ultrasound-guided biopsy cores. The sensitivity, specificity, positive and negative predictive values, and accuracy of ⁶⁸Ga-PSMA PET/CT were determined. In addition, the correlation between the miPSMA-ES and the detection rate of PCa was also analyzed. Univariate logistic regression models were established using ⁶⁸Ga-PSMA PET/CT semiquantitative analysis parameters to predict the outcome of repeat prostate biopsy. Results: The median age of patients was 65 y (range, 53-81 y), and the median PSA level was 18.0 ng/mL (range, 5.48-49.77 ng/mL). PCa was detected in 15 of 31 patients (48.4%), and 12 of 31 patients (38.7%) had clinically significant PCa (csPCa). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ⁶⁸Ga-PSMA PET/CT in the diagnosis of csPCa were 100.0%, 68.4%, 66.7%, 100.0%, and 80.6%, respectively. The detection rate of PCa increased with the increase in miPSMA-ES. The detection rates of csPCa in the miPSMA-ES 0-1, 2, and 3 groups were 0%, 54.5%, and 85.7%, respectively. Semiquantitative analysis of ⁶⁸Ga-PSMA PET/CT images showed that predictive models based on the SUV_max of prostate lesion, tumor-to-normal-prostate background SUV_max, and tumor-to-normal-liver background SUV_max could effectively predict csPCa; area under the curves were 0.930, 0.877, and 0.956, respectively. Conclusion: This study preliminarily confirmed that ⁶⁸Ga-PSMA PET/CT imaging, combined with PET/ultrasound-guided prostate biopsy, can effectively detect csPCa. Prebiopsy ⁶⁸Ga-PSMA PET/CT had predictive value for csPCa in the studied patient population.

Keywords: PET/CT; PSMA; biopsy; prostate cancer.

FIGURE 1.

Prostate biopsy algorithm for study subjects. DRE = digital rectal examination.

FIGURE 2.

Receiver-operating-characteristic curve analysis of ⁶⁸Ga-PSMA PET/CT semiquantitative analysis index for prediction of csPCa. SUV_T/BGp = tumor–to–normal-prostate background SUV_max.