Evaluation of MR imaging-targeted biopsies of the prostate in biopsy-naïve patients. A single centre study

Abstract

Purpose: To evaluate the differences in prostate cancer detection rate and biopsy effectiveness between magnetic resonance imaging (MRI) target biopsy (TB) and transperineal standard biopsy (SB) in biopsy-naïve patients.

Material and methods: Between October 2014 and April 2016, 60 men with a mean age of 64.1±6.7 (SD) years (range: 53-82 years) were prospectively enrolled. All patients underwent a prostate MRI study, evaluated by two radiologists, before undergoing the biopsy. A transperineal 12-core SB was carried out before TB, without the information from the MRI. The detection rate for all tumors and for clinically significant tumors (CS) was recorded. Sampling variables such as the proportion of cores positive for CS cancer (PCP-CS) and the maximum cancer core length (MCCL) were also calculated. The ability of MRI to predict the presence of a CS tumor at biopsy was studied using a sector analysis. Patients with negative biopsies were followed during a minimum of 12 months.

Results: The detection rate for SB and TB was 53.3% (32/60) and 46.7% (28/60) respectively for all tumors (P=0.289) and 45% (27/60) in both techniques for CS tumors. TB obtained a larger PCP-CS (P<0.001) and MCCL (P=0.018). The sensitivity, specificity, positive predictive value, negative predictive value and cancer prevalence was 83.3%, 92.9%, 83.3%, 92.9% and 30% for peripheral zone sectors and 43.8%, 97.1%, 70.0%, 91.8% and 13,3% for transitional zone sectors. The proportion of patients that showed an increase of PSA faster than 0.75ng/mL/year after a negative biopsy was 26.1%.

Conclusion: Detection rate of prostate cancer did not show significant differences between a TB and a SB technique in biopsy-naïve patients. However, targeted prostate biopsies demonstrated a better sampling effectiveness thus reducing the cores needed to diagnose clinically significant tumors.

Keywords: Cancer detection; Magnetic resonance imaging (MRI); Prostate biopsy; Prostate cancer; Targeted biopsy.