By: Dan Sperling, MD

The use of multiparametric MRI (mpMRI) in prostate interventions is transforming prostate interventions.[i] Imaging advances now enable precise identification of suspicious areas in the prostate gland (detection), and facilitate accurate targeting for purposes of biopsy (diagnosis) and focal thermal ablation (treatment).

MRI-guided targeted prostate biopsies are proving to have several advantages over transrectal ultrasound (TRUS) guided biopsies. The average number of needles is greatly reduced with MRI-guided biopsies, thus minimizing the risks of infection, blood in urine (hematuria), blood in semen (hemospermia), urinary and erectile difficulties, and post-biopsy hospitalization.

Initially, real time MRI-guided biopsies were inefficient due to the need for multiple imaging slices in order to validate placement of the biopsy needle guide. This difficulty was addressed by both the use of small radiofrequency coils, and the development of active tracking markers in an MR-compatible robotic manipulator that could be remotely controlled.[ii] More recently, clinical studies are being done on the feasibility of automatic needle-guide tracking by using a real-time phase-only cross correlation (POCC) algorithm-based sequence for transrectal 3-T in-bore MRI-guided prostate biopsies, which allows automatic calculation of the position and orientation of an imaging slice with respect to the placement of the needle guide marker, similar to an ultrasound probe. In December 2014, an international team of researchers published their results on using POCC tracking with 11 men suspected of having prostate cancer due to elevated PSA but whose previous TRUS biopsies were negative.[iii] 3T mpMRI identified 25 suspicious regions among the 11 men, and a total of 38 needle samples were taken under real-time MRI guidance. In all cases, POCC use was feasible for tracking, with a median guidance time per target of 1.5 minutes; nineteen of the 38 cores samples were positive for prostate cancer.

An interesting study on the patient experience of real-time MRI-guided biopsies vs. TRUS biopsies was conducted by a German group out of the Center of Radiology, Charité – Universitätsmedizin Berlin.[iv] Their purpose was to record side effects, complications, and patient acceptance of MRI-guided biopsy. They enrolled 54 men, all of whom had at least one previous negative TRUS biopsy. Based on suspicious areas found during MRI, a median of four needles per patient (range of 1-9 needles) were taken under real-time MRI guidance. All patients then underwent TRUS biopsy with a median of 10 needles (range of 6-14 samples). A week after the MRI-guided biopsies, patients were interviewed by phone regarding their experience of pain during the biopsy, and side effects (blood in urine or semen, rectal bleeding, fever and chills) of each biopsy procedure, and which of the two they preferred.

Not surprisingly, 65% of the men preferred the MRI-guided biopsy, and 82% said they would undergo the same procedure again. Pain and bleeding duration were significantly less for MRI vs. TRUS-guided biopsies. Hematuria was less common MRI-GB was preferred by 65% (35/54), and 82% (44/54) would undergo MRI-GB again. Pain intensity (P = 0.005) and bleeding duration (P = 0.004) were significantly lower for MRI-GB compared with TRUS-GB. Hematuria was less common with MRI-guided sampling, and there was a high correlation between bleeding intensity and duration with TRUS procedures. The researchers concluded that “MRI-GB of the prostate seems to have fewer side effects and less pain intensity than TRUS-GB and was preferred by the majority of patients.”

Given the continuing evolution of precision and efficiency of real time 3T mpMRI-guided prostate biopsies, and an observable increase in patient interest in this procedure over TRUS-guided biopsies[v] it is anticipated that availability of this technology will continue to expand.

[i] Ghai S, Trachtenberg J. In-bore MRI interventions: current status and future applications. Curr Opin Urol. 2015 May;25(3):205-11. doi: 10.1097/MOU.0000000000000160.

[ii] de Oliveira, A., Rauschenberg, J., Beyersdorff, D., Semmler, W., and Bock, M.Automatic passive tracking of an endorectal prostate biopsy device using phase-only cross-correlation. Magn Reson Med. 2008; 59: 1043–1050

[iii] Zamecnik P, Schouten MG, Krafft AJ et al. Automated real-time needle-guide tracking for fast 3-T MR-guided transrectal prostate biopsy: a feasibility study. Radiology. 2014 Dec;273(3):879-86. doi: 10.1148/radiol.14132067. Epub 2014 Jul 25.

[iv] Egbers N, Schwenke C, Maxeiner A et al. MRI-guided core needle biopsy of the prostate: acceptance and side effects. Diagn Interv Radiol. 2015 Apr 7. doi: 10.5152/dir.2014.14372. [Epub ahead of print] Full article available at http://www.dirjournal.org/eng/makale/1210/62/Full-Text

[v] See patient discussion board “Focal Laser Ablation Patients” at www.inspire.com. Registration required to access discussion boards.