Thermal analysis of the surrounding anatomy during 3-D MRI-guided transurethral ultrasound prostate therapy

Mathieu Burtnyk, Rajiv Chopra, Michael Bronskill

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Previous numerical simulations have shown that MRI-guided transurethral ultrasound therapy can generate highly accurate volumes of thermal coagulation conforming to 3-D human prostate geometries. The goal of this work is to simulate, quantify and evaluate the thermal impact of these treatments on the rectum, pelvic bone, neurovascular bundles (NVB) and urinary sphincters. This study used twenty 3-D anatomical models of prostate cancer patients and detailed bio-acoustic simulations incorporating an active feedback algorithm which controlled a rotating, planar ultrasound transducer (17-4×3mm elements, 4.7/9.7 MHz, 10Wac/cm2). Heating of the adjacent surrounding anatomy was evaluated using thermal tolerances reported in the literature. Heating of the rectum poses the most important safety concern and is influenced largely by the water temperature flowing through an endorectal cooling device; temperatures of 7-37°C are required to limit potential damage to less than 10mm 3 on the outer 1 mm layer of rectum. Significant heating of the pelvic bone was predicted in 30% of the patient models with an ultrasound frequency of 4.7 MHz; setting the frequency to 9.7 MHz when the bone is less than 10 mm away from the prostate reduced heating in all cases below the threshold for irreversible damage. Heating of the NVB was significant in 75% of the patient models in the absence of treatment planning; this proportion was reduced to 5% by using treatment margins of up to 4 mm. To avoid damaging the urinary sphincters, margins from the transducer of 2-4 mm should be used, depending on the transurethral cooling temperature. Simulations show that MRI-guided transurethral therapy can treat the entire prostate accurately. Strategies have been developed which, along with careful treatment planning, can be used to avoid causing thermal injury to the rectum, pelvic bone, NVB and urinary sphincters.

Original languageEnglish (US)
Title of host publication9th International Symposium on Therapeutic Ultrasound - ISTU 2009
Pages251-255
Number of pages5
DOIs
StatePublished - Mar 30 2010
Event9th International Symposium on Therapeutic Ultrasound, ISTU 2009 - Aix-en-Provence, France
Duration: Sep 24 2009Sep 26 2009

Publication series

NameAIP Conference Proceedings
Volume1215
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other9th International Symposium on Therapeutic Ultrasound, ISTU 2009
CountryFrance
CityAix-en-Provence
Period9/24/099/26/09

Keywords

  • 3-D control
  • MRI-guided
  • Prostate
  • Thermal therapy
  • Thermometry
  • Transurethral
  • Treatment planning

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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  • Cite this

    Burtnyk, M., Chopra, R., & Bronskill, M. (2010). Thermal analysis of the surrounding anatomy during 3-D MRI-guided transurethral ultrasound prostate therapy. In 9th International Symposium on Therapeutic Ultrasound - ISTU 2009 (pp. 251-255). (AIP Conference Proceedings; Vol. 1215). https://doi.org/10.1063/1.3367154