Twelve-month prostate volume reduction after MRI-guided transurethral ultrasound ablation of the prostate
To quantitatively assess 12-month prostate volume (PV) reduction based on T2-weighted MRI and immediate post-treatment contrast-enhanced MRI non-perfused volume (NPV), and to compare measurements with predictions of acute and delayed ablation volumes based on MR-thermometry (MR-t), in a central radiology review of the Phase I clinical trial of MRI-guided transurethral ultrasound ablation (TULSA) in patients with localized prostate cancer.
Materials and methods
Treatment day MRI and 12-month follow-up MRI and biopsy were available for central radiology review in 29 of 30 patients from the published institutional review board-approved, prospective, multi-centre, single-arm Phase I clinical trial of TULSA. Viable PV at 12 months was measured as the remaining PV on T2-weighted MRI, less 12-month NPV, scaled by the fraction of fibrosis in 12-month biopsy cores. Reduction of viable PV was compared to predictions based on the fraction of the prostate covered by the MR-t derived acute thermal ablation volume (ATAV, 55°C isotherm), delayed thermal ablation volume (DTAV, 240 cumulative equivalent minutes at 43°C thermal dose isocontour) and treatment-day NPV. We also report linear and volumetric comparisons between metrics.
After TULSA, the median 12-month reduction in viable PV was 88%. DTAV predicted a reduction of 90%. Treatment day NPV predicted only 53% volume reduction, and underestimated ATAV and DTAV by 36% and 51%.
Quantitative volumetry of the TULSA phase I MR and biopsy data identifies DTAV (240 CEM43 thermal dose boundary) as a useful predictor of viable prostate tissue reduction at 12 months. Immediate post-treatment NPV underestimates tissue ablation.
• MRI-guided transurethral ultrasound ablation (TULSA) achieved an 88% reduction of viable prostate tissue volume at 12 months, in excellent agreement with expectation from thermal dose calculations.
• Non-perfused volume on immediate post-treatment contrast-enhanced MRI represents only 64% of the acute thermal ablation volume (ATAV), and reports only 60% (53% instead of 88% achieved) of the reduction in viable prostate tissue volume at 12 months.
• MR-thermometry-based predictions of 12-month prostate volume reduction based on 240 cumulative equivalent minute thermal dose volume are in excellent agreement with reduction in viable prostate tissue volume measured on pre- and 12-month post-treatment T2w-MRI.
KeywordsHigh-intensity focused ultrasound ablation Prostate cancer Interventional magnetic resonance imaging Thermometry Biopsy, needle
Acute thermal ablation volume
Dice similarity coefficient
Delayed thermal ablation volume
Magnetic resonance imaging
Transurethral ultrasound ablation
This study has received funding by Profound Medical Inc.
Compliance with ethical standards
The scientific guarantor of this publication is Heinz-Peter Schlemmer.
Conflict of interest
David Bonekamp is speaker for Profound Medical Inc.
Mathieu Burtnyk is director of clinical affairs of Profound Medical Inc. with a salary and stock options.
Robert Staruch is senior clinical scientist at Profound Medical Inc., with a salary and stock options.
Jason M. Hafron declares: Amgen-paid speaker, Armune Biosciences Inc, advisory board/paid speaker, Dendreon-Advisory Board, paid speaker, Myriad, and paid speaker, United Physicians- Board of directors
Heinz-Peter Schlemmer declares: Consulting fee or honorarium: Siemens, Curagita, Profound, Bayer. Travel support: Siemens, Curagita, Profound, Bayer. Board Member: Curagita. Consultancy: Curagita, Bayer. Grants/Grants pending: BMBF, Deutsche Krebshilfe, Dietmar-Hopp-Stiftung, Roland-Ernst-Stiftung. Payment for lectures: Siemens, Curagita, Profound, Bayer.
Boris Hadaschik declares: Personal fees: Janssen, BMS, Astrellas, Bayer. Grants: Janssen, Astrellas, BMS, German Cancer Aid, German Research Foundation.Grant: Profound Medical.
Gencay Hatiboglu declares: Consultancy for BMS.
Timur Kuru has nothing to declare.
James Relle has nothing to declare.
Maya Mueller-Wolf has nothing to declare.
Matthias Röthke declares consulting fee and payment for lectures: Siemens Healthineers, Curagita AG.
Sascha Pahernik reports personal fees from Bayer, personal fees from Astellas, personal fees from Janssen, outside the submitted work.
Valentin Popeneciu has nothing to declare.
Joseph Chin declares: Investigator and consultant for Profound Medical Inc., US HIFU, Endocare; Paid Advisory Board/Consultancy for Abbvie, Johnson & Johnson/Janssen, Amgen, Tersera, Novartis, Astellas, Bayer, Sanofi-Aventis.
Michele Billia has nothing to declare.
Kiran Nandalur has nothing to declare.
Markus Hohenfellner has nothing to declare.
Statistics and biometry
No complex statistical methods were necessary for this paper.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional Review Board approval was obtained.
Study subjects or cohorts overlap
Some study subjects or cohorts have been previously reported in Chin JL, Billia M, Relle J, et al. Magnetic resonance imaging-guided transurethral ultrasound ablation of prostate tissue in patients with localized prostate cancer: a prospective Phase 1 clinical trial. Eur Urol. 2016;70(3):447–455.
• multicentre study
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