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Title: Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model

Abstract

Purpose: To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue. Materials and Methods: MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation. Results: The mean short-axis diameters of the coagulation zones were 1.34 {+-} 0.14, 1.45 {+-} 0.13, and 1.74 {+-} 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 {+-} 0.09 and 1.26 {+-} 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 {+-} 0.65, 2.85 {+-} 0.72, and 4.45 {+-} 0.47 cm{sup 3} for MW ablation at outputs of 25W, 35W, and 45W and 1.18 {+-} 0.30 and 2.29 {+-} 0.55 cm{sup 3} got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature wasmore » achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations. Conclusion: MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.« less

Authors:
 [1];  [2];  [1];  [2]; ;  [1];  [3]; ;  [1]
  1. RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute Aachen (Germany)
  2. RWTH Aachen University, Department of Pathology Aachen University Hospital (Germany)
  3. Nara Medical University, Department of Radiology (Japan)
Publication Date:
OSTI Identifier:
22066592
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cardiovascular and Interventional Radiology; Journal Volume: 35; Journal Issue: 4; Other Information: Copyright (c) 2012 Springer Science+Business Media, LLC and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ABLATION; CATTLE; MAMMARY GLANDS; MHZ RANGE 100-1000; MICROWAVE RADIATION; NECROSIS; RADIOLOGY

Citation Formats

Tanaka, Toshihiro, E-mail: toshihir@bf6.so-net.ne.jp, Westphal, Saskia, E-mail: swestphal@ukaachen.de, Isfort, Peter, E-mail: isfort@hia.rwth-aachen.de, Braunschweig, Till, E-mail: tbraunschweig@ukaachen.de, Penzkofer, Tobias, E-mail: penzkofer@hia.rwth-aachen.de, Bruners, Philipp, E-mail: bruners@rad.rwth-aachen.de, Kichikawa, Kimihiko, E-mail: kkichika@naramed-u.ac.jp, Schmitz-Rode, Thomas, E-mail: smiro@hia.rwth-aachen.de, and Mahnken, Andreas H., E-mail: mahnken@rad.rwth-aachen.de. Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model. United States: N. p., 2012. Web. doi:10.1007/S00270-011-0253-4.
Tanaka, Toshihiro, E-mail: toshihir@bf6.so-net.ne.jp, Westphal, Saskia, E-mail: swestphal@ukaachen.de, Isfort, Peter, E-mail: isfort@hia.rwth-aachen.de, Braunschweig, Till, E-mail: tbraunschweig@ukaachen.de, Penzkofer, Tobias, E-mail: penzkofer@hia.rwth-aachen.de, Bruners, Philipp, E-mail: bruners@rad.rwth-aachen.de, Kichikawa, Kimihiko, E-mail: kkichika@naramed-u.ac.jp, Schmitz-Rode, Thomas, E-mail: smiro@hia.rwth-aachen.de, & Mahnken, Andreas H., E-mail: mahnken@rad.rwth-aachen.de. Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model. United States. doi:10.1007/S00270-011-0253-4.
Tanaka, Toshihiro, E-mail: toshihir@bf6.so-net.ne.jp, Westphal, Saskia, E-mail: swestphal@ukaachen.de, Isfort, Peter, E-mail: isfort@hia.rwth-aachen.de, Braunschweig, Till, E-mail: tbraunschweig@ukaachen.de, Penzkofer, Tobias, E-mail: penzkofer@hia.rwth-aachen.de, Bruners, Philipp, E-mail: bruners@rad.rwth-aachen.de, Kichikawa, Kimihiko, E-mail: kkichika@naramed-u.ac.jp, Schmitz-Rode, Thomas, E-mail: smiro@hia.rwth-aachen.de, and Mahnken, Andreas H., E-mail: mahnken@rad.rwth-aachen.de. 2012. "Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model". United States. doi:10.1007/S00270-011-0253-4.
@article{osti_22066592,
title = {Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model},
author = {Tanaka, Toshihiro, E-mail: toshihir@bf6.so-net.ne.jp and Westphal, Saskia, E-mail: swestphal@ukaachen.de and Isfort, Peter, E-mail: isfort@hia.rwth-aachen.de and Braunschweig, Till, E-mail: tbraunschweig@ukaachen.de and Penzkofer, Tobias, E-mail: penzkofer@hia.rwth-aachen.de and Bruners, Philipp, E-mail: bruners@rad.rwth-aachen.de and Kichikawa, Kimihiko, E-mail: kkichika@naramed-u.ac.jp and Schmitz-Rode, Thomas, E-mail: smiro@hia.rwth-aachen.de and Mahnken, Andreas H., E-mail: mahnken@rad.rwth-aachen.de},
abstractNote = {Purpose: To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue. Materials and Methods: MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation. Results: The mean short-axis diameters of the coagulation zones were 1.34 {+-} 0.14, 1.45 {+-} 0.13, and 1.74 {+-} 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 {+-} 0.09 and 1.26 {+-} 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 {+-} 0.65, 2.85 {+-} 0.72, and 4.45 {+-} 0.47 cm{sup 3} for MW ablation at outputs of 25W, 35W, and 45W and 1.18 {+-} 0.30 and 2.29 {+-} 0.55 cm{sup 3} got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations. Conclusion: MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.},
doi = {10.1007/S00270-011-0253-4},
journal = {Cardiovascular and Interventional Radiology},
number = 4,
volume = 35,
place = {United States},
year = 2012,
month = 8
}
  • This study was designed to compare feasibility, safety, and effectiveness of microwave (MW) ablation versus radiofrequency (RF) ablation of lung tissue in a rabbit model. Twenty New Zealand White rabbits were submitted to MW (n = 10, group A) or RF ablation (n = 10, group B). The procedures were performed with a prototype MW ablation device with a 1.6-cm radiating section antenna (Valleylab MW Ablation System) and with a 2-cm exposed-tip RF electrode (Cool-tip RF Ablation System). At immediate computed tomography increase in density, maximum diameters (D1-D3) of ablation zones were measured and ablation volume was calculated. Histopathologic assessmentmore » was performed 3 and 7 days after the procedure. Technical success was achieved in nine of 10 rabbits in each group. One death occurred in group B. Complications included pneumothorax (group A, n = 4; group B, n = 4), abscess (group A, n = 1; group B, n = 1), and thoracic wall burn (group A, n = 4). No significant differences were demonstrated in attenuation increase (P = 0.73), dimensions (P = 0.28, 0.86, 0.06, respectively, comparing D1-D3) and volume (P = 0.17). At histopathology, ablation zones were similar, with septal necrosis, edema, hemorrhage, and peripheral lymphocytic infiltrate. Complete thrombosis of more than 90% of vessels up to 2 mm in diameter was depicted at the periphery of the ablation zone in group A specimens. In group B specimens, complete thrombosis was depicted in 20% of vessels. Feasibility and safety of MW and RF ablation are similar in a lung rabbit model. MW ablation produces a greater damage to peripheral small vessels inducing thrombosis.« less
  • The purpose of this study was to evaluate the effectiveness of a newly developed perfused monopolar radiofrequency (RF) probe with an umbrella-shaped array. A perfused umbrella-shaped monopolar RF probe based on a LeVeen electrode (Boston Scientific Corp., Natick, MA, USA) with a 3-cm array diameter was developed. Five different configurations of this electrode were tested: (a) perfusion channel/endhole, (b) perfusion channel/endhole + sideholes, (c) 1 cm insulation removed at the tip, (d) 1 cm insulation removed at the tip + perfusion channel/endhole, and (e) 1 cm insulation removed at the tip + perfusion channel/endhole + sideholes. An unmodified LeVeen electrodemore » served as a reference standard. RF ablations were performed in freshly excised bovine liver using a commercial monopolar RF system with a 200-W generator (RF 3000; Boston Scientific Corp.). Each electrode was tested 10 times applying the vendor's recommended ablation protocol combined with the preinjection of 2 ml 0.9% saline. Volumes and shapes of the lesions were compared. Lesions generated with the original LeVeen electrode showed a mean volume of 12.74 {+-} 0.52 cm{sup 3}. Removing parts of the insulation led to larger coagulation volumes (22.65 {+-} 2.12 cm{sup 3}). Depending on the configuration, saline preinjection resulted in a further increase in coagulation volume (25.22 {+-} 3.37 to 31.28 {+-} 2.32 cm{sup 3}). Besides lesion volume, the shape of the ablation zone was influenced by the configuration of the electrode used. We conclude that saline preinjection in combination with increasing the active tip length of the umbrella-shaped LeVeen RF probe allows the reliable ablation of larger volumes in comparison to the originally configured electrode.« less
  • The purpose of this study was to assess the efficacy of a new perfused-cooled electrode that uses a single pump for creating a large ablation zone in explanted bovine liver. This was done by comparing with the radiofrequency (RF) ablation zones that were created with a monopolar cooled electrode to the RF ablation zones that were created by the new perfused-cooled electrode. We developed a new perfused-cooled electrode that uses a single pump by modifying a 17-gauge cooled electrode (Radionics) with a 2.5-cm outer metallic sheath (15-gauge) in order to allow use of the internal cooling water (5.85 % hypertonicmore » saline) for the infused saline. Thirty ablation zones were created in explanted bovine livers (12-min ablation cycle; pulsed technique; 2000 mA, maximum) with three different regimens: group A, RF ablation with the 17-gauge cooled electrode; group B, RF ablation with the 15-gauge cooled electrode; group C, RF ablation with the perfused-cooled electrode. T2-weighted magnetic resonance (MR) imaging was obtained immediately after RF ablation for calculating volumes of the ablation zone. Following MR imaging, the ablation zones were excised and measured for transverse diameters and vertical diameters. The transverse diameter, vertical diameter, and the calculated volumes of the ablation zones on MR imaging were compared among the groups. Ablation zones created with the perfused-cooled electrode (group C) were significantly larger than those created with the 17-gauge cooled electrode (group A) and the 15-gauge cooled electrode (group B) according to the transverse diameter and vertical diameter on the gross specimens (p < 0.05): 3.6 {+-} 0.38 cm and 4.4 {+-} 0.20 cm in group A, 3.7 {+-} 0.08 cm and 4.6 {+-} 0.16 cm in group B, and 5.4 {+-} 0.65 cm and 6.0 {+-} 0.56 cm in group C, respectively. On the MR imaging, the calculated volumes of the ablation zones in group C were significantly larger than those in groups A and B (p < 0.05): 23.1 {+-} 8.7 cm{sup 3} in group A, 28.9 {+-} 5.7 cm{sup 3} in group B, and 80.0 {+-} 34 cm{sup 3} in group C, respectively. A new perfused-cooled electrode using a single pump could efficiently increase the size of the ablation zone in liver compared with a monopolar cooled electrode, and this was due to its simultaneous use of internal cooling and saline infusion.« less
  • Purpose. To develop a flow model for bovine livers for extensive bench testing of technical improvements or procedure-related developments of radiofrequency ablation excluding animal experiments. Methods. The perfusion of bovine livers directly from the slaughterhouse was simulated in a liver perfusion tank developed for the experimental work. The liver perfusion medium used was a Tyrode solution prepared in accordance with physiologic criteria (as for liver transplants) which was oxygenated by an oxygenator and heated to 36.5 deg. C. Portal vein circulation was regulated via a flow- and pressure-controlled pump and arterial circulation using a dialysis machine. Flow rate and pressuremore » were adjusted as for the physiology of a human liver converted to bovine liver conditions. The fluid discharged from the liver was returned into the perfusion system through the vena cava. Extendable precision swivel arms with the radiofrequency probe attached were mounted on the liver perfusion tank. RFA was conducted with the RF3000 generator and a 2 cm LeVeen needle (Boston Scientific, Ratingen, Germany) in a three-dimensional grid for precise localization of the generated thermolesions. Results. Four bovine livers weighing 8.4 {+-} 0.4 kg each were prepared, connected to the perfusion system, and consecutively perfused for the experiments. Mean arterial flow was 569 {+-} 43 ml/min, arterial pressure 120 mmHg, portovenous flow 1440 {+-} 305 ml/min, and portal pressure 10 mmHg. Macroscopic evaluation after the experiments revealed no thrombi within the hepatic vessels. A total of 136 RF thermolesions were generated with an average number of 34 per liver. Mean RF duration was 2:59 {+-} 2:01 min:sec with an average baseline impedance of 28.2 {+-} 3.4 ohms. The mean diameter of the thermolesions along the puncture channel was 22.98 {+-} 4.34 mm and perpendicular to the channel was 23.27 {+-} 4.82 mm. Conclusion. Extracorporeal perfusion of bovine livers with consecutive standardized RF ablation was feasible. The bovine liver flow model seems to allow extensive, standardized evaluation of technical or procedure-related developments of RF systems.« less
  • This study was designed to determine the magnitude and spatial distribution of temperature elevations when using 480 kHz RF and 2.45 GHz microwave energy in ex vivo liver models. A total of 60 heating cycles (20 s at 90 W) were performed in normal, RF-ablated, and microwave-ablated liver tissues (n = 10 RF and n = 10 microwave in each tissue type). Heating cycles were performed using a 480-kHz generator and 3-cm cooled-tip electrode (RF) or a 2.45-GHz generator and 14-gauge monopole (microwave) and were designed to isolate direct heating from each energy type. Tissue temperatures were measured by usingmore » fiberoptic thermosensors 5, 10, and 15 mm radially from the ablation applicator at the depth of maximal heating. Power delivered, sensor location, heating rates, and maximal temperatures were compared using mixed effects regression models. No significant differences were noted in mean power delivered or thermosensor locations between RF and microwave heating groups (P > 0.05). Microwaves produced significantly more rapid heating than RF at 5, 10, and 15 mm in normal tissue (3.0 vs. 0.73, 0.85 vs. 0.21, and 0.17 vs. 0.09 Degree-Sign C/s; P < 0.05); and at 5 and 10 mm in ablated tissues (2.3 {+-} 1.4 vs. 0.7 {+-} 0.3, 0.5 {+-} 0.3 vs. 0.2 {+-} 0 Degree-Sign C/s, P < 0.05). The radial depth of heating was {approx}5 mm greater for microwaves than RF. Direct heating obtained with 2.45-GHz microwave energy using a single needle-like applicator is faster and covers a larger volume of tissue than 480-kHz RF energy.« less