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Int J Hyperthermia. 2017 Sep;33(6):624-634. doi: 10.1080/02656736.2017.1303751. Epub 2017 Mar 21.

Computational modelling of internally cooled wet (ICW) electrodes for radiofrequency ablation: impact of rehydration, thermal convection and electrical conductivity.

Author information

1
a Biomedical Synergy, Department of Applied Mathematics, Universitat Politècnica de València , Valencia , Spain.
2
b Food Technology Department , Universitat Politècnica de València , Valencia , Spain.
3
c Biomedical Synergy, Department of Electronic Engineering , Universitat Politècnica de València , Valencia , Spain.

Abstract

PURPOSE:

(1) To analyse rehydration, thermal convection and increased electrical conductivity as the three phenomena which distinguish the performance of internally cooled electrodes (IC) and internally cooled wet (ICW) electrodes during radiofrequency ablation (RFA), (2) Implement a RFA computer model with an ICW which includes these phenomena and (3) Assess their relative influence on the thermal and electrical tissue response and on the coagulation zone size.

METHODS:

A 12-min RFA in liver was modelled using an ICW electrode (17 G, 3 cm tip) by an impedance-control pulsing protocol with a constant current of 1.5 A. A model of an IC electrode was used to compare the ICW electrode performance and the computational results with the experimental results.

RESULTS:

Rehydration and increased electrical conductivity were responsible for an increase in coagulation zone size and a delay (or absence) in the occurrence of abrupt increases in electrical impedance (roll-off). While the increased electrical conductivity had a remarkable effect on enlarging the coagulation zone (an increase of 0.74 cm for differences in electrical conductivity of 0.31 S/m), rehydration considerably affected the delay in roll-off, which, in fact, was absent with a sufficiently high rehydration level. In contrast, thermal convection had an insignificant effect for the flow rates considered (0.05 and 1 mL/min).

CONCLUSIONS:

Computer results suggest that rehydration and increased electrical conductivity were mainly responsible for the absence of roll-off and increased size of the coagulation zone, respectively, and in combination allow the thermal and electrical performance of ICW electrodes to be modelled during RFA.

KEYWORDS:

Computer modelling; electrical conductivity; internally cooled electrode; radiofrequency ablation; rehydration

PMID:
28540782
DOI:
10.1080/02656736.2017.1303751
[Indexed for MEDLINE]

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