Background
Positron emission tomography (PET)/computed tomography (CT) with 68Ga-labeled prostate-specific membrane antigen ligand (68Ga-PSMA) may represent the most promising alternative to multiparametric magnetic resonance imaging (mpMRI) for prostate cancer (PCa) diagnosis.
Objective
To test the diagnostic performance of 68Ga-PSMA PET/CT in this clinical context.
Design, setting, and participants
From January 2017 to December 2018 we prospectively enrolled 97 patients with persistently elevated prostate-specific antigen and/or Prostate Health Index score, negative digital rectal examination, and previous negative biopsy. We also included patients with either negative mpMRI or contraindications to or positive mpMRI but previous negative biopsy.
Intervention
Patients underwent 68Ga-PSMA PET/CT with additional pelvic reconstruction.
Outcome measurements and statistical analysis
The primary endpoint of the study was the diagnostic performance of 68Ga-PSMA PET/CT in detecting malignant lesions and clinically significant PCa (Gleason score [GS] ≥7).
Results and limitations
68Ga-PSMA PET/transrectal ultrasound fusion biopsy was performed in 64 of 97 patients (66%) for 114 regions of interest (ROIs). Forty patients (41%) had already undergone mpMRI with either a negative result for PCa (n = 15; 22 ROIs) or a positive mpMRI result but a previous negative biopsy. According to pathology, 23 patients (36%) had evidence of PCa: eight (16 ROIs) with GS 6, 13 (21 ROIs) with GS 7 (3 + 4 or 4 + 3), one (2 ROIs) with GS 8, and one (2 ROIs) with GS 10. Clinically significant PCa was identified in four patients with previous negative mpMRI (25%). PET/CT demonstrated PCa in seven patients (14 ROIs) with previous positive mpMRI and negative biopsy. The median maximum standardized uptake value (SUVmax) and median SUV ratio were significantly higher for PCa lesions than for benign lesions (p < 0.001). Optimal cutoff points obtained for SUVmax (>5.4) and SUV ratio (>2.2) could identify clinically significant PCa with accuracy of 81% and 90%, respectively.
Conclusions
In our cohort of patients with high suspicion of cancer,68Ga-PSMA PET/CT was capable of detecting malignancy and accurately identifying clinically relevant PCa.
