The Open Biomedical Engineering Journal




ISSN: 1874-1207 ― Volume 13, 2019

Contribution of Direct Heating, Thermal Conduction and Perfusion During Radiofrequency and Microwave Ablation



Wolfgang Schramm1, 2, Deshan Yang3, Bradford J Wood4, Frank Rattay2, Dieter Haemmerich*, 1, 5
1 Div. of Pediatric Cardiology, Medical University of South Carolina, Charleston, SC, USA
2 Div. Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
3 Dept. of Electrical and Computer Engineering, University of Wisconsin, WI, USA
4 Dept. Diagnostic Radiology, National Cancer Institute, NIH, Bethesda, MD, USA
5 Dept. of Bioengineering, Clemson University, Clemson, SC, USA

Abstract

Both radiofrequency (RF) and microwave (MW) ablation devices are clinically used for tumor ablation. Several studies report less dependence on vascular mediated cooling of MW compared to RF ablation. We created computer models of a cooled RF needle electrode, and a dipole MW antenna to determine differences in tissue heat transfer.

We created Finite Element computer models of a RF electrode (Cooled needle, 17 gauge), and a MW antenna (Dipole, 13 gauge). We simulated RF ablation for 12 min with power controlled to keep maximum tissue temperature at 100 ºC, and MW ablation for 6 min with 75 W of power applied. For both models we considered change in electric and thermal tissue properties as well as perfusion depending on tissue temperature. We determined tissue temperature profile at the end of the ablation procedure and calculated effect of perfusion on both RF and MW ablation.

Maximum tissue temperature was 100 ºC for RF ablation, and 177 ºC for MW ablation. Lesion shape was ellipsoid for RF, and tear-drop shaped for MW ablation. MW ablation is less affected by tissue perfusion mainly due to the shorter ablation time and higher tissue temperature, but not due to MW providing deeper heating than RF. Both MW and RF applicators only produce significant direct heating within mm of the applicator, with most of the ablation zone created by thermal conduction.

Both RF and MW applicators only directly heat tissue in close proximity of the applicators. MW ablation allows for higher tissue temperatures than RF since MW propagation is not limited by tissue desiccation and charring. Higher temperatures coupled with lower treatment times result in reduced effects of perfusion on MW ablation.



Article Information


Identifiers and Pagination:

Year: 2007
Volume: 1
First Page: 47
Last Page: 52
Publisher Id: TOBEJ-1-47
DOI: 10.2174/1874120700701010047

Article History:

Received Date: 18/7/2007
Revision Received Date: 03/9/2007
Acceptance Date: 03/9/2007
Electronic publication date: 19/9/2007
Collection year: 2007

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2007 Bentham Science Publishers Ltd.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/) which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.


* Address correspondence to this author at the Division of Pediatric Cardiology, Medical Univ. South Carolina, USA; E-mail: haemmer@musc.edu


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