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J Vasc Interv Radiol. 2009 Jan;20(1):118-24. doi: 10.1016/j.jvir.2008.09.021. Epub 2008 Nov 18.

Radiofrequency ablation: simultaneous application of multiple electrodes via switching creates larger, more confluent ablations than sequential application in a large animal model.

Author information

1
Department of Radiology, University of Wisconsin, Clinical Sciences Center, Madison, WI 53792, USA. clbrace@wisc.edu

Abstract

PURPOSE:

To compare radiofrequency (RF) ablations created by using a sequential technique to those created simultaneously by using a switching algorithm in ex vivo and in vivo liver models.

MATERIALS AND METHODS:

RF ablation was performed by using either sequential or switched application of three cooled electrodes in a 2-cm triangular array in ex vivo bovine liver (28 total ablations) and in vivo swine liver (12 total ablations) models. For sequential ablations, electrodes were powered for 12 minutes each with a 5-minute rest interval between activations to simulate electrode repositioning. Switched ablations were created by using a multiple-electrode switching system for 12 minutes. Temperatures were measured during ex vivo experiments at four points in the ablation zone. Ablation zones were measured for minimum and maximum diameter, cross-sectional area, and isoperimetric ratio. Mann-Whitney and Wilcoxon matched pairs tests were used to identify differences between groups.

RESULTS:

The switched application created larger and more circular zones of ablation than did the sequential application, with mean (+/-standard deviation) ex vivo cross-sectional areas of 25.4 cm(2) +/- 5 .3 and 18.8 cm(2) +/- 6.6 (P = .001), respectively, and mean in vivo areas of 17.1 cm(2) +/- 5.1 and 13.2 cm(2) +/- 4.2 (P < .05). Higher temperatures and more rapid heating occurred with the switched application; switched treatments were 74% faster than sequential treatments (12 vs 46 minutes). In the sequential group, subsequent ablations grew progressively larger due to local ischemia.

CONCLUSIONS:

Switched application of three electrodes creates larger, more confluent ablations in less time than sequential application. Thermal synergy and ablation-induced ischemia both substantially influence multiple-electrode ablations.

PMID:
19019701
PMCID:
PMC2667960
DOI:
10.1016/j.jvir.2008.09.021
[Indexed for MEDLINE]
Free PMC Article

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