Bipolar Radiofrequency Ablation Using Wet-Cooled Electrodes: An In Vitro Experimental Study in Bovine Liver
Jeong Min Lee1,
Joon Koo Han,
Se Hyung Kim,
Seung Hong Choi,
Su Kyung An,
Chang Jin Han and
Byun Ihn Choi
1 All authors: Department of Radiology and Institute of Radiation Medicine,
Seoul National University College of Medicine and Clinical Research Institute,
Seoul National University, 28 Yeongon dong, Jongno-gu, Seoul 110-744, South
Korea.
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Fig. 1. —Photograph showing wet-cooled electrode containing two
coaxial lumina that enable circulation of cooling water through electrode and
separate lumen for saline interstitial infusion. Hole for saline infusion was
positioned in proximal portion of sheath (arrow).
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Fig. 2A. —General setting in simultaneous monopolar and bipolar
radiofrequency ablation in in vitro bovine liver model. Illustration of
sequential monopolar mode shows wet-cooled electrode and injector used to
continuously inject hypertonic saline. Thermocouple (T1) is inserted 15 mm
from electrodes (E1 and E2). Sequential monopolar mode applies current to one
of two probes; current flows from probe to dispersive pad.
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Fig. 2B. —General setting in simultaneous monopolar and bipolar
radiofrequency ablation in in vitro bovine liver model. Illustration of
bipolar mode shows two wet-cooled electrodes used as active electrode (E1) and
dispersive electrode (E2), respectively. Current then flows from one electrode
to other. T1 = thermocouple.
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Fig. 3A. —Comparison of radiofrequency-induced coagulation created by
applying radiofrequency in two groups. Photograph shows cut section of
specimen along electrode insertion axis from group A (monopolar mode).
Arrowheads indicate electrode insertion sites. Vertical solid arrow indicates
vertical diameter, and horizontal dotted arrow indicates long-axis
diameter.
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Fig. 3B. —Comparison of radiofrequency-induced coagulation created by
applying radiofrequency in two groups. In photograph of cut section of same
specimen (A) along perpendicular plane to A, arrow indicates
short-axis diameter.
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Fig. 3C. —Comparison of radiofrequency-induced coagulation created by
applying radiofrequency in two groups. Photograph of specimen from group B
(bipolar mode) shows that shortest vertical diameter of coagulation necrosis
at midpoint between two electrodes (arrowheads) is larger in bipolar
mode than in monopolar mode.
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Fig. 3D. —Comparison of radiofrequency-induced coagulation created by
applying radiofrequency in two groups. Photograph shows cut section of same
specimen (C) along plane perpendicular to C.
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Fig. 4. —Photograph of gross specimen from group B (bipolar mode)
shows impedance rise during radiofrequency ablation. Large vessel
(arrow) is included in ablation region.
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Fig. 5. —Graph of mean temperatures midway between two electrodes in
each group. Note that higher temperature is achieved in bipolar mode ( )
than in simultaneous monopolar mode (•).
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Copyright © 2005 by the American Roentgen Ray Society.
