Using prostate-specific membrane antigen positron-emission tomography to guide prostate biopsies and stage men at high-risk of prostate cancer.

OBJECTIVE: To assess whether a diagnostic pathway in which prostate-specific membrane antigen (PSMA) positron-emission tomography (PET)/computed tomography (CT) is used as a single imaging modality is feasible to guide targeted biopsy and to detect clinically significant prostate cancer (csPCa) in biopsy-naïve men at high-risk of disease. PATIENTS AND METHODS: A total of 60 men with a prostate-specific antigen (PSA) level of 20-50 ng/mL underwent 18 F-PSMA(DCFPyL)-PET/CT prior to prostate biopsies in this prospective, non-randomised cohort study. Magnetic resonance imaging (MRI) was not performed. Using a 12-segment mapping model of the prostate, PSMA-guided targeted biopsy was performed along with systematic biopsies. The detection rate of PCa and csPCa was assessed for combined systematic and targeted biopsy, and for targeted biopsy only. csPCa was defined as a prostate biopsy with an International Society of Uropathology (ISUP) Grade Group ≥2. RESULTS: Lesions suspicious for PCa in the prostate gland were observed on all PSMA-PET/CTs. A total of 27/60 men (45%) already had metastatic disease on staging 18 F-PSMA(DCFPyL)-PET/CT. Combined PSMA-guided targeted and systematic biopsies detected PCa in 56/60 (93.3%) patients, with 52 of them (92.9%) having csPCa. PSMA-guided targeted biopsy, if performed as a single biopsy modality, identified PCa in 52/60 men (86.7%) and in 27/27 men (100%) men with metastases. CONCLUSIONS: Using the PSMA-driven single imaging modality pathway in biopsy-naïve men at high-risk of PCa, a substantial number of diagnostic MRI scans could be avoided while at the same time obtaining adequate targeting, staging, and detection of csPCa.

18F-FDG PET-CT Findings Before and After Laparoscopic Cryoablation of Small Renal Mass: An Initial Report.

The aim of this study was to describe the characteristics of positron emission tomography (PET) molecular imaging combined with low-dose computed tomography (CT) in small renal mass (SRM) treated with cryoablation (CA). Currently, treatment success is defined by the absence of contrast enhancement at CT. However, the use of contrast is relatively contraindicated in patients with renal function impairment, mandating alternative follow-up strategies. Several reasons were identified as criteria for performing PET-CT before and/or after SRM-CA in 9 patients, and the results were retrospectively studied. The histology revealed renal cell carcinoma in 7 patients and oncocytoma in 2 patients. In 6 patients, a PET-CT was performed before and after CA. In one patient, the PET-CT was performed only before CA and in 2 patients only after CA. Before CA, clearly there was metabolic uptake of fluorine-18 fluorodeoxyglucose (18F-FDG) in the SRM in all patients. Following CA, the absence of 18F-FDG uptakes in the SRM could clearly be noticed. However, the tracer cannot always be distinguished from focal recurrence or reactive inflammatory tissue. In one patient, asymptomatic metastatic bone lesions were noticed when performing PET-CT at follow-up. This pilot study with 18F-FDG PET-CT for the follow-up of SRM cryosurgery showed that 18F-FDG PET-CT imaging could be used to characterize cryoablative tissue injury at different times after CA.