Comparison of Renal Ablation with Monopolar Radiofrequency and Hypertonic-Saline-Augmented Bipolar Radiofrequency: In Vitro and In Vivo Experimental Studies
Jeong Min Lee1,
Joon Koo Han1,
Seung Hong Choi1,
Se Hyung Kim1,
Jae Young Lee1,
Kyung Sook Shin2,
Chang Jin Han1 and
Byung Ihn Choi1
1 Department of Radiology and the Institute of Radiation Medicine, Seoul
National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul
110-744, South Korea.
2 Department of Radiology, Chungnam National University College of Medicine, 6
Munhwa-dong, Daejeon 301-747, Korea.
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Fig. 1A. —Instruments used for hypertonic-saline (HS)-augmented bipolar
radiofrequency ablation. Illustration shows perfused-cooled electrode that
allows simultaneous internal cooling and saline infusion. RF =
radiofrequency.
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Fig. 1B. —Instruments used for hypertonic-saline (HS)-augmented bipolar
radiofrequency ablation. Photograph shows HS-augmented bipolar radiofrequency
ablation in canine kidney. Two perfused cooled electrodes (arrows)
were inserted into kidney. A thermocouple (arrowhead) was placed
between the two electrodes to monitor the local tissue temperature during the
procedure.
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Fig. 2A. —Graphic depiction of tissue impedance (bottom wave),
radiofrequency current (middle wave), and power changes (top
wave) during radiofrequency ablation during in vivo experiments.
Monopolar radiofrequency ablation of canine kidney in vivo is shown.
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Fig. 2B. —Graphic depiction of tissue impedance (bottom wave),
radiofrequency current (middle wave), and power changes (top
wave) during radiofrequency ablation during in vivo experiments.
Hypertonic-saline-augmented bipolar radiofrequency ablation of canine kidney
in vivo is shown.
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Fig. 4A. —Photographs used to compare radiofrequency-induced coagulation that
was created ex vivo in bovine kidney by monopolar and bipolar modes. Note that
short- and long-axis diameters of coagulation necrosis were larger in bipolar
mode. B, Photographs show specimen from group A (monopolar mode)
(A) and from group B (hypertonic-saline-augmented bipolar mode)
(B).
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Fig. 4B. —Photographs used to compare radiofrequency-induced coagulation that
was created ex vivo in bovine kidney by monopolar and bipolar modes. Note that
short- and long-axis diameters of coagulation necrosis were larger in bipolar
mode. Photographs show specimen from group A (monopolar mode) (A) and
from group B (hypertonic-saline-augmented bipolar mode) (B).
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Fig. 5A. —Images of kidneys treated with hypertonic-saline (HS)-augmented
bipolar (A–D) and (E and F) monopolar
radiofrequency for 10 min in dog model. Nonenhanced areas were determined in
each slice and summed to determine volume. Contrast-enhanced CT scan obtained
3 days after HS-augmented bipolar radiofrequency ablation reveals
radiofrequency-induced nonenhancing region (arrows) in kidney.
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Fig. 5B. —Images of kidneys treated with hypertonic-saline (HS)-augmented
bipolar (A–D) and (E and F) monopolar
radiofrequency for 10 min in dog model. Nonenhanced areas were determined in
each slice and summed to determine volume. Photograph of gross renal section
of kidney seen in A shows white central region surrounded by
hemorrhagic rim (arrows).
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Fig. 5C. —Images of kidneys treated with hypertonic-saline (HS)-augmented
bipolar (A–D) and (E and F) monopolar
radiofrequency for 10 min in dog model. Nonenhanced areas were determined in
each slice and summed to determine volume. Photograph of gross renal section
in kidney seen in A stained with 2% 2,3,5,-triphenyltetrazolium
chloride reveals well-defined white ablation zone (arrows).
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Fig. 5D. —Images of kidneys treated with hypertonic-saline (HS)-augmented
bipolar (A–D) and (E and F) monopolar
radiofrequency for 10 min in dog model. Nonenhanced areas were determined in
each slice and summed to determine volume. Photomicrograph of radiofrequency
ablation zone in kidney seen in A obtained 3 days after procedure shows
confined area of coagulation necrosis (N) surrounded by peripheral zones of
hemorrhage (H), and normal renal parenchyma (R). Note typical coagulation
necrosis with preserved architecture of kidney having ghostlike tubular
profiles with very faintly staining nuclei. (H and E, x40)
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Fig. 5E. —Images of kidneys treated with hypertonic-saline (HS)-augmented
bipolar (A–D) and (E and F) monopolar
radiofrequency for 10 min in dog model. Nonenhanced areas were determined in
each slice and summed to determine volume. Contrast-enhanced CT scan obtained
3 days after monopolar radiofrequency ablation reveals focal nonenhanced
region (arrows) in kidney. Note dimension of nonenhanced area is
smaller than that shown in A.
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Fig. 5F. —Images of kidneys treated with hypertonic-saline (HS)-augmented
bipolar (A–D) and (E and F) monopolar
radiofrequency for 10 min in dog model. Nonenhanced areas were determined in
each slice and summed to determine volume. Photograph of gross renal section
of kidney seen in E stained with 2% 2,3,5,-triphenyltetrazolium
chloride shows well-defined white ablation zone (arrows). Note
dark-brown charring along site of electrode insertion.
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Copyright © 2005 by the American Roentgen Ray Society.
= monopolar radiofrequency ablation, 
= bipolar radiofrequency ablation. Error bars represent 95% confidence
interval for mean temperature.