Does multiparametric MRI 3D fusion biopsy biopsy improve detection rate ? Preliminary experience

Franco Bertolotto1, Angelo Naselli2, Paolo Puppo2
  • 1 Centro Urologico di Eccellenza (San Remo)
  • 2 Istituto Clinico Humanitas "Mater Domini" (Castellanza)

Objective

Random prostate biopsy is up to date the standard procedure for the diagnosis of prostate cancer. In the last 10 years several schemes with different number of cores has been proposed to optimize the ratio among number of patients diagnosed and number of patients biopsied. There are convincing evidences that 12 – 18 cores obtained from the peripheral zone are the best approach in patients which are submitted to the first biopsy. Nevertheless the diagnostic yield is about 35% and more important guidelines about repeated biopsy yet lack. Multi-parametric 1.5 – 3 tesla MRI has demonstrated a great ability in detection foci of cancer in the prostate specimen. 3D TRUS guided biopsy gives the operator the opportunity to verify the exact angulation and length of the core in the prostate before and after the puncture. Therefore it seems a logic consequence to “fuse” the 2 technologies and perform “real time” MRI – targeted punctures of the prostate [1-4]. We report our preliminary experience with the dedicated Koelis workstation.

Methods and results

Consecutive patients submitted to multiparametric 1.5 tesla MRI (m-MR) with an elevated PSA and a negative digital rectal examination were included in the study. The m-MR was read by a dedicated radiologist and suspected foci were graded according to the ESUR score [4]. The radiological images were fused with the 3D TRUS images obtained during the procedure. Target zones (defined as having a moderate to high risk of cancer) were indexed in the 3D model. 12 random scores from the peripheral zone of prostate (divided in apex, middle and base) were obtained from each patients. Thereafter targeted cores were obtained. Each core was stored separately and appointed of a serial number. At the end the cores were send to the pathologist with the 3D scheme of the prostate and of the cores obtained, each one identified by the respective serial number. The “per patient” detection rate was computed and an analysis “per core” was performed to assess the diagnostic yield of targeted biopsy in respect to random biopsy by means of the chi square analysis. From November 2012 to January 2013 31 patients were submitted to m-MR 3D TRUS elastic fusion prostate biopsies were performed by means of the Koelis workstation. Mean age of patients enrolled was 65 year, range 49 – 77. Mean PSA was 8.5 ng/mL (range 2.9 – 25 ng/mL). Twenty seven patients had at least one suspected zone identified with m-MR. A mean of 5 targeted cores were obtained, range 2 – 5. In all 21 out of 31 (68%) had prostate cancer. The detection rate in the 28 cases with a suspected m-MR was 18/27 (67%). The “per single” core analysis showed that 31 cores out of 116 obtained from target zones had prostate cancer whereas 75 out of 432 (14%) obtained outside targeted zone were positive. The odds ratio was 1.763 (95% CI 1.043 – 2.882, p 0.033)

Discussion

The “per patient” detection rate no advantage has been measured in our series notwithstanding the accuracy of targeted biopsy is far higher than random biopsy according to the available literature [1-4]. The most reliable explanations are the small number of patients examined and the learning curve of the operator. Higher the number of patients enrolled higher the detection rate is expected to increase by means of a sensibly greater accuracy of m-MRI targeted biopsy. In regard to the learning curve, the major problem was to achieve a correct fusion among the m-MRI and 3D TRUS images by a “shaping” procedure which is mostly operator and experience dependent and is fundamental to direct correctly the puncture. Anyway the technology is surely promising and the increasing experience may lead to to assess the real impact of targeted biopsy in the clinical practice

References

1) Sonn GA, Natarajan S, Margolis DJ, Macairan M, Lieu P, Huang J, Dorey FJ, Marks LS. Targeted biopsy in the detection of prostate cancer using an office based magnetic resonance ultrasound fusion device. J Urol. 2013 Jan;189(1):86-92

2) Pinto PA, Chung PH, Rastinehad AR, Baccala AA Jr, Kruecker J, Benjamin CJ, Xu S, Yan P, Kadoury S, Chua C, Locklin JK, Turkbey B, Shih JH, Gates SP, Buckner C, Bratslavsky G, Linehan WM, Glossop ND, Choyke PL, Wood BJ. Magnetic resonance imaging/ultrasound fusion guided prostate biopsy improves cancer detection following transrectal ultrasound biopsy and correlates with multiparametric magnetic resonance imaging. J Urol. 2011 Oct;186(4):1281-5

3) Hadaschik BA, Kuru TH, Tulea C, Rieker P, Popeneciu IV, Simpfendörfer T, Huber J, Zogal P, Teber D, Pahernik S, Roethke M, Zamecnik P, Roth W, Sakas G, Schlemmer HP, Hohenfellner M. A novel stereotactic prostate biopsy system integrating pre-interventional magnetic resonance imaging and live ultrasound fusion. J Urol. 2011 Dec;186(6):2214-20

4) Portalez D, Mozer P, Cornud F, Renard-Penna R, Misrai V, Thoulouzan M, Malavaud B. Validation of the European society of urogenital radiology scoring system for prostate cancer diagnosis on multiparametric magnetic resonance imaging in a cohort of repeat biopsy patients. Eur Urol. 2012 Dec;62(6):986-96

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