Magnetic Resonance Imaging/Ultrasound Fusion Guided prostate biopsy: preliminary experiences
It’s known that the TRUS has a low sensitivity and specificity in identifying cancerous prostate lesions. In contrast, in many years of testing, multiparametric MRI has proved extremely effective in the diagnostic and treatment of prostate cancer but it is difficult to use as a guide to the biopsy. The stereotactic transperineal prostate biopsy is a new technique that combines MRI images with real time imaging by TRUS to identify and mapping prostate lesions suspicious for malignancy. This method allows to exploit the advantages of each method by increasing the precision of the samples targeted and allowing you to store data and images of the procedure so that it is repeatable and can be used in the follow-up in case of active surveillance. It also allows any executions of focal therapies: HIFU, cryotherapy and brachytherapy. The aim of the study is to detect the cancer detection rate of prostate stereotactic trans perineal biopsy, compare the specificity of MR images with the ultrasound, highlight the differences in histological outcomes in targeted sampling with image fusion with eco guided mapping of patient with biochemical suspicion of neoplasia clinically negative.
Materials and Methods
Between December 2014 and February 2015 we underwent prostatic stereotactic trans perineal biopsy 10 patients with biochemical suspect of prostate cancer (mean age 60.4 years, range 46-74, mean PSA 7.6 range from 4.2 to 11.7 average prostate volume 71 ml range 40-110 ml). All patients had previously undergone TRUS guided biopsy (9 pcs 1 mapping, 1 pc 2 mapping). Before sampling was performed a multiparametric MRI 1.5T with T2-weighted imaging, diffusion and with contrast medium. The images were processed with software Watson to identify suspicious areas for ETP and then subsequently superimposed on the TRUS images captured in real time during the mapping. The drawings were made by trans perineal sampling with needles 18G using a perforated screen for pointing and needle guide. The software in the course of image overlay indicates the hole in which it must be inserted the needle. The procedure was performed in the lithotomy position and spinal anesthesia and required use of the operating room for about 70 minutes per patient. The preparation has provided antibiotics (levofloxacin 1 pill the night before) and evacuative fleet the night before and the same morning. For each patient were performed an average of 24.1 samples (range 24-33).
In all patients MRI revealed suspected areas where to point specimens. 7 biopsies were positive for prostate Ca (70%). In patients with adenocarcinoma, 85% of the cores taken in suspect areas were positive. 3 adenocarcinomas had a Gleason score (GS) 4 + 4, 2 adenocarcinomas GS 4 + 3, 1 adenocarcinoma GS 3 + 4, 1 adenocarcinoma GS 3 + 3. 2 patients (20%) had urinary retention that required placement of a bladder catheter removed after 5 days with resumption of spontaneous voiding. 3 patients (30%) had hematuria resolved spontaneously within 2 days. No cases of UTI or pelvic-perineal hematoma. All patients reported hemospermia.
In our experience, this technique showed to be better in detection of prostate cancer (70% positive) than mapping performed with use of ultrasound alone (in a series of 1275 patients since 2008 we had 34, 5% of detection rate for cancer in 440 cases). Furthermore this series of Patients consist in a second look for cancer in a previous negative mapping.
We need to define the inclusion criteria to select patients for the method. Multiparametric MRI showed a sensitivity and a specificity better than transrectal ultrasounds for the detection of prostate cancer. Should it be performed in all patients with negative DRE and rising PSA? Stereotactic trans perineal biopsy has to be reserved exclusively for the re-mapping? Which patients will benefit from early diagnosis in terms of survival and quality of life?
The method has proven effective in the diagnosis of prostatic adenocarcinoma in patients with suspected RM. At the moment the need for specific equipment and hospitalization of the patient to perform the mapping in anesthesia with the related costs, impose a limited use of the technique. This platform can also be used in the emerging field of focal prostate therapy, is to guide treatment and for the follow-up of treated lesions, or to conduct active surveillance.
At the time the limit of the technique is the inability to detect lesions <3 mm and the execution of MRI in patients with prosthetic not compatible with MRI or pacemakers and cardiac defibrillators.
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