MRI-Guided In-Bore Biopsy: Differences Between Prostate Cancer Detection and Localization in Primary and Secondary Biopsy Settings

OBJECTIVE: The objective of our study was to evaluate transrectal MRI-guided in-bore biopsy in patients who either were biopsy-naive (primary biopsy) or had undergone at least one previous negative transrectal ultrasound-guided biopsy (secondary biopsy) with regard to cancer detection rate, tumor localization, and lesion size. MATERIALS AND METHODS: In total, 1602 biopsy cores from 297 consecutive patients (mean ± SD, 66.1 ± 7.8 years; median prostate-specific antigen value, 8.2 ng/mL) in primary (n = 160) and secondary (n = 137) prostate biopsy settings were evaluated in this retrospective study. All patients previously underwent prostate MRI (T2-weighted imaging, DWI, dynamic contrast-enhanced imaging) at 3 T. All described lesions were biopsied with MRI-guided in-bore biopsy and were examined histologically. RESULTS: In 148 patients, overall 511 cores were positive for prostate cancer. Clinically significant prostate cancer (any Gleason pattern ≥ 4) was found in 82.4% of patients. The prostate cancer detection rate for patients who underwent primary biopsies was 55.6% and was 43.1% for patients who underwent secondary biopsies. In patients with primary versus secondary biopsies, prostate cancer was located peripherally in 62.9% versus 49.5% (p = 0.04), in the transition zone in 27.4% versus 27.5% (p = 1.0), and in the anterior stroma in 10.3% versus 22.9% (p < 0.01), respectively. The prostate cancer detection rates for patients with smaller prostate volumes (< 30 vs 30-50 vs > 50 mL; p < 0.01) or for patients with larger lesions (> 0.5 vs 0.25-0.5 vs < 0.25 cm(3); p < 0.01) were significantly higher. CONCLUSION: MRI-guided in-bore biopsy led to high detection rates in primary and secondary prostate biopsies. Prostate cancer detection rates were significantly higher for patients with larger lesions and smaller prostate glands. In patients who underwent secondary biopsies, prostate cancer was located in the anterior stroma at a significantly more frequent rate.