2304 STEREOTACTIC PROSTATE BIOPSY WITH PRE-INTERVENTIONAL MRI AND LIVE US FUSION

Abstract

INTRODUCTION AND OBJECTIVES: The key challenge for focal therapy of prostate cancer is to identify index lesions. In this context, we describe our initial experience with a new stereotactic prostate biopsy system, which integrates pre-interventional MRI data with periinterventional ultrasound for perineal prostate biopsies. METHODS: 33 patients were stereotactically biopsied (mean age of 64yrs., mean PSA level of 8.2ng/ml and mean prostate vol. of 40ml). 21 of these 33 patients had already had a negative transrectal US-guided biopsy. All men underwent multimodal 3 Tesla MRI without endorectal coil including diffusion weighted imaging and dynamic contrast enhanced sequences as well as MR-spectroscopy. Suspicious lesions were marked by radiologists with over 10 years experience in reading prostate MRI before the obtained data were transferred to the stereotactic biopsy system. Using a custom-made biplane TRUS probe mounted on a stepper device, 3D ultrasound data were generated to set the anatomic landmarks. Then MRI and TRUS imaging data were fused manually. As a result, the suspicious MRI lesions were superimposed onto the TRUS data. Next, 3D biopsy planning was performed including systematic biopsies from the peripheral and transitional zones of the prostate. Perineal biopsies were taken under live US imaging, and the location of each biopsy was documented in 3D. RESULTS: 14 out of 33 patients were diagnosed with prostate cancer. These results showed a positive correlation between MRI findings and histopathology in 22 out of 33 patients. In MRI lesions marked as highly suspicious, the detection rate was 100%. Evaluating the biopsies from lesions marked as highly and as questionable suspicious together, prostate cancer was detected in 27.95%. In comparison, only 8% of the additional systematic biopsies were positive. Target registration error of the first 554 biopsy cores was 1.9 mm. For adverse effects, one patient experienced urinary retention. Postinterventional hemorrhage or urinary tract infection did not occur. CONCLUSIONS: Perineal stereotactic prostate biopsies guided by the combination of MRI and ultrasound enable effective examination of suspicious MRI lesions. Additionally, each biopsy core taken may be documented accurately for its location in 3D. Thus, MRI data may be validated and different treatment options stratified in depth. At the same time the morbidity of the procedure was minimal.