title: Thermal Energy during Irreversible Electroporation and the Influence of Different Ablation Parameters.
abstract: OBJECTIVE
  Irreversible electroporation (IRE) uses high-voltage electric fields to achieve cell death. Although the mechanism of IRE is mainly designated as nonthermal, development of secondary Joule heating is inevitable. The study purpose was to gain understanding of temperature development and distribution during IRE.
  
  
  METHODS
  IRE was performed in a transparent polyacrylamide gel resembling soft tissue. Mechanical effects, changes in temperature gradient, and absolute temperature changes were measured with three different optical techniques (high-speed, color Schlieren, and infrared imaging) to investigate the effect on temperature of variations in voltage, pulse length, active tip length (ATL), interelectrode distance, electrode configuration (parallel, convergent, and divergent), and sequential pulsing (pulse delivery interrupted by breaks). The total delivered energy was calculated.
  
  
  RESULTS
  A temperature gradient, starting at the tips of both electrodes and expanding toward each other, developed immediately with pulse delivery. Temperatures increased with increasing voltage (by 2.5°C-40.4°C), pulse length (by 5.3°C-9.8°C), ATL (by 5.9°C-17.6°C), and interelectrode distance (by 7.6°C-21.5°C), in accordance with higher energy delivery. Nonparallel electrode placement resulted in heterogeneous temperature distribution with the peak temperature focused in the area with the shortest interelectrode distance. Sequential pulse delivery significantly reduced the temperature increase compared with continuous pulsing (4.3°C vs 11.7°C).
  
  
  CONCLUSIONS
  Voltage, pulse length, interelectrode distance, ATL, and electrode configuration each have a strong effect on temperature development and distribution during IRE. Sequential pulsing reduces the extent and volume of thermal distribution and may prove beneficial with respect to procedural safety.
authors.affiliation: Department of Urology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Electronic address: w.vandenbos@amc.uva.nl.
authors.forename: Willemien
authors.initials: W
authors.lastname: van den Bos
authors.affiliation: Departments of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Hester J
authors.initials: HJ
authors.lastname: Scheffer
authors.affiliation: Department of Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jantien A
authors.initials: JA
authors.lastname: Vogel
authors.affiliation: Department of Urology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Peter G K
authors.initials: PG
authors.lastname: Wagstaff
authors.affiliation: Department of Urology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: de Bruin
authors.affiliation: Departments of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Marcus C
authors.initials: MC
authors.lastname: de Jong
authors.affiliation: Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Martin J C
authors.initials: MJ
authors.lastname: van Gemert
authors.affiliation: Department of Urology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jean J M C H
authors.initials: JJ
authors.lastname: de la Rosette
authors.affiliation: Departments of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Martijn R
authors.initials: MR
authors.lastname: Meijerink
authors.affiliation: Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: John H
authors.initials: JH
authors.lastname: Klaessens
authors.affiliation: Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Rudolf M
authors.initials: RM
authors.lastname: Verdaasdonk
mesh_terms: D055011:Ablation Techniques; D000180:Acrylic Resins / Q000737:chemistry*; D004553:Electric Conductivity; D018274:Electroporation; D004735:Energy Transfer; D005740:Gases; D006358:Hot Temperature; D008953:Models, Anatomic; D013817:Thermography; D013997:Time Factors; D014741:Video Recording
chemical_list: D000180:Acrylic Resins; D005740:Gases; C016680:polyacrylamide gels