Matthijs J. SCHELTEMA, Arnoud W POSTEMA, Daniel M. de BRUİN, Mara BUİJS, Marc R ENGELBRECHT, M Pilar LAGUNA, Hessel WİJKSTRA, Theo M. de REİJKE, Jean J.M.C.H. de la ROSETTE

Irreversible electroporation for the treatment of localized prostate cancer: a summary of imaging findings and treatment feedback

PURPOSE Imaging plays a crucial role in ablative therapies for prostate cancer (PCa). Irreversible electroporation (IRE) is a new treatment modality used for focal treatment of PCa. We aimed to demonstrate what imaging modalities can be used by descriptively reporting contrast-enhanced ultrasonography (CEUS), multiparametric magnetic resonance imaging (mpMRI), and grey-scale transrectal ultrasound (TRUS) results. Furthermore, we aimed to correlate quantitatively the ablation zone seen on mpMRI and CEUS with treatment planning to provide therapy feedback. METHODS Imaging data was obtained from two prospective multicenter trials on IRE for localized low- to intermediate-risk PCa. The ablation zone volume (AZV) seen on mpMRI and CEUS was 3D reconstructed to correlate with the planned AZV. RESULTS Descriptive examples are provided using mpMRI, TRUS, and CEUS for treatment planning and follow-up after IRE. The mean AZV on T2-weighted imaging 4 weeks following IRE was 12.9 cm3 (standard deviation [SD]=7.0), 5.3 times larger than the planned AZV. Linear regression showed a positive correlation (r=0.76, P = 0.002). For CEUS the mean AZV was 20.7 cm3 (SD=8.7), 8.5 times larger than the planned AZV with a strong positive correlation (r=0.93, P = 0.001). Prostate volume is reduced over time (mean= -27.5%, SD=11.9%) due to ablation zone fibrosis and deformation, illustrated by 3D reconstruction. CONCLUSION The role of imaging in conjunction with IRE is of crucial importance to guide clinicians throughout the treatment protocol. CEUS and mpMRI may provide essential treatment feedback by visualizing the ablation zone dimensions and volume.

Tam Metin

___

1. Valerio M, Ahmed HU, Emberton M, et al. The role of focal therapy in the management of localised prostate cancer: a systematic review. Eur Urol 2013; 66:732–751.

2. Davalos RV, Mir LM, Rubinsky B. Tissue ablation with irreversible electroporation. Ann Biomed Eng 2005; 33:223–231.

3. Lee EW, Wong D, Prikhodko SV, et al. Electron microscopic demonstration and evaluation of irreversible electroporation-induced nanopores on hepatocyte membranes. J Vasc Interv Radiol 2012; 23:107–113.

4. Neal RE, Millar JL, Kavnoudias H, et al. In vivo characterization and numerical simulation of prostate properties for non-thermal irreversible electroporation ablation. Prostate 2014; 74:458–468.

5. van den Bos W, de Bruin DM, Jurhill RR, et al. The correlation between the electrode configuration and histopathology of irreversible electroporation ablations in prostate cancer patients. World J Urol 2016; 34:657–664.

6. Ting F, Tran M, Böhm M, et al. Focal irreversible electroporation for prostate cancer: functional outcomes and short-term oncological control. Prostate Cancer Prostatic Dis 2016; 19:46–52.

7. Murray KS, Ehdaie B, Musser J, et al. Pilot study to assess safety and clinical outcomes of irreversible electroporation for partial gland ablation in men with prostate cancer. J Urol 2016; 196:883–890.

8. Valerio M, Stricker PD, Ahmed HU, et al. Initial assessment of safety and clinical feasibility of irreversible electroporation in the focal treatment of prostate cancer. Prostate Cancer Prostatic Dis 2014; 17:343–347.

9. van den Bos W, de Bruin DM, van Randen A, et al. MRI and contrast-enhanced ultrasound imaging for evaluation of focal irreversible electroporation treatment: results from a phase I-II study in patients undergoing IRE followed by radical prostatectomy. Eur Radiol 2015; 26:2252–2260.

10. Muller BG, van den Bos W, Brausi M, et al. Follow-up modalities in focal therapy for prostate cancer: results from a Delphi consensus project. World J Urol 2015; 33:1503–1509.

11. Scheltema MJ, Tay KJ, Postema AW, et al. Utilization of multiparametric prostate magnetic resonance imaging in clinical practice and focal therapy: report from a Delphi consensus project. World J Urol 2017; 35:695–701.

12. Valerio M, Shah TT, Shah P, et al. Magnetic resonance imaging-transrectal ultrasound fusion focal cryotherapy of the prostate: a prospective development study. Urol Oncol Semin Orig Investig 2017; 35:150.e1–150.e7.

13. van den Bos W, de Bruin DM, Muller BG, et al. The safety and efficacy of irreversible electroporation for the ablation of prostate cancer: a multicentre prospective human in vivo pilot study protocol. BMJ Open 2014; 4:e006382.

14. Scheltema MJ, van den Bos W, de Bruin DM, et al. Focal vs extended ablation in localized prostate cancer with irreversible electroporation; a multi-center randomized controlled trial. BMC Cancer 2016; 16:299.

15. Barentsz JO, Weinreb JC, Verma S, et al. Synopsis of the PI-RADS v2 guidelines for multiparametric prostate magnetic resonance imaging and recommendations for use. Eur Urol 2016; 69:41–49.

16. Kuenen MPJ, Saidov TA, Wijkstra H, Mischi M. Contrast-ultrasound dispersion imaging for prostate cancer localization by improved spatiotemporal similarity analysis. Ultrasound Med Biol 2013; 39:1631–1641.

17. Dickinson L, Ahmed HU, Allen C, et al. Magnetic resonance imaging for the detection, localisation, and characterisation of prostate cancer: Recommendations from a European consensus meeting. Eur Urol 2011; 59:477–494.

18. van den Bos W, Jurhill RR, de Bruin DM, et al. Histopathological outcomes after irreversible electroporation for prostate cancer: results of an ablate and resect study. J Urol 2016; 196:552–559.

19. Van Den Bos W, Muller BG, Ahmed H, et al. Focal therapy in prostate cancer: International multidisciplinary consensus on trial design. Eur Urol 2014; 65:1078–1083.

20. Tran M, Thompson J, Böhm M, et al. Combination of multiparametric MRI and transperineal template-guided mapping biopsy of the prostate to identify candidates for hemi-ablative focal therapy. BJU Int 2016; 117:48–54.

21. Rubinsky L, Guenther E, Mikus P, Stehling M, Rubinsky B. Electrolytic effects during tissue ablation by electroporation. Technol Cancer Res Treat 2016; 15: NP95–103.