Targeted PET/TRUS software fusion‑guided biopsy in men with persistently elevated PSA and negative mpMRI after previous negative biopsy: A feasibility study and preliminary results

INTRODUCTION & OBJECTIVES: Multiparametric Magnetic Resonance Imaging (mpMRI) is increasingly performed in men with one or more previous negative biopsy to diagnose Prostate Cancer (PCa) and a Prostate Imaging Reporting and Data System (PI-RADS) score was established for clinical use. Unfortunately the rate of false negative mpMRI remains not negligible, as some potentially important cancers are MRI-invisible. One of the most promising tools for the investigation of PCa is represented by molecular imaging with Positron Emission Tomography (PET). We investigated the technical feasibility and the clinical impact of PET/TRUS software fusion‑guided biopsy in men with persistently elevated PSA and negative mpMRI after previous negative biopsy. MATERIAL & METHODS: From May 2015 to September 2015, patients with persistently elevated PSA, atypical small acinar proliferation (ASAP), high grade prostate intraepithelial neoplasia (HG-PIN) and/or positive digital rectal examination (DRE) after at least one negative biopsy, who underwent a diagnostic prostate 3T mpMRI revealing PI-RADS < 3, were considered for the current prospective nested PET/TRUS fusion biopsy study. All patients underwent 11C-choline PET with dedicated acquisition and image reconstruction of the pelvis by using a 256x256 matrix (Discovery GE 690 PET/CT, GE Healthcare, Wisconsin, USA) For the definition of prostatic tumour localization, we considered as positive any focal uptake of 11C-choline superior to the background activity. For PET/TRUS fusion-guided prostate biopsy, the Bio-Jet™ fusion system and software (D&K Technologies, Barum, Germany) were used. The outcomes of interest were the feasibility and the detection of prostate cancer. RESULTS: Over 92 consecutive patients, who were candidate for mpMRI/TRUS software fusion‑guided biopsy, 6 patients (mean age 66,4 years ± 9.4; tPSA 9.98 ng/ml ± 2.31; negative DRE) showed a PI-RADS < 3. Those patients, who maintained a biochemical suspected for PCa consented to undergo 11C-choline PET. Prior to biopsy, the 11C-choline PET was uploaded as DICOM file in the Bio-Jet™ fusion system and software (Figure 1). The PET showed a median of 1.5 (range 1-3) lesions per patient; overall 10 lesions were found. The median lesion size was 12 mm (range 5-19). The anatomical distribution of the lesion was: 3 in the peripheral zone and 7 in the transitional/central zone. A median of 3 cores (range 2-4; overall 31) was taken per single lesion. Over 31 cores, 10 (32.2%), from 5 lesions, were positive. PCa was detected in 3 patients (50%). In one patient the PCa was located in the peripheral zone, while in others in the central-transitional zone. All those three patients presented a Gleason score > 6 (1 pt. GS 4+3 and 2 pts. GS 4+5). One patient showed a granulomatous prostatitis and two a benign prostatic hyperplasia. No significant complications were recorded. CONCLUSIONS: The 11C-choline PET/TRUS software target fusion biopsy resulted technically feasible, simple and effective in detecting high risk PCa. The use of metabolic PET information for a fusion target biopsy in the setting of patients with persistently high risk of bearing PCa and negative mpMRI after previous negative biopsies might represent a further tool in the hand of urologists. Before its implementation in daily practice further studies remain mandatory.