Comparison of four microwave ablation devices: an experimental study in ex vivo bovine liver.

PURPOSE To compare volume, sphericity, and short-axis diameter of the coagulation zone of four commercially available microwave ablation systems with three technical concepts in an ex vivo setting and to formulate mathematical models to predict these quantities. MATERIALS AND METHODS Two high-power systems (systems A and B), a system that enables simultaneous use of three antennas (system C), and a non-perfusion-cooled system that automatically adapts power and frequency (system D) were tested in ex vivo bovine livers (108 ablations). Coagulation volume, sphericity, and mean short-axis diameter were assessed, and mathematical functions were fitted for each system and assessed with the coefficient of determination (R(2)). Analysis of variance and Tukey post hoc tests were used for interdevice comparison after 5 and 10 minutes and after maximum recommended ablation time. RESULTS Volume and short-axis diameter were determined by using a mathematical model for every system, with coefficients of determination of 0.75-0.98 and 0.70-0.97, respectively. Correlation for determination of sphericity was lower (R(2) = 0.01-0.68). Mean results with ablation performed according to manufacturer recommendations were as follows: Volume, sphericity, and short-axis diameter were 57.5 cm(3), 0.75, and 43.4 mm, respectively, for system A; 72.3 cm(3), 0.68, and 45.5 mm, respectively, for system B; 17.1 cm(3), 0.58, and 26.8 mm, respectively, for system C (one antenna); 76.5 cm(3), 0.89, and 50.6 mm, respectively, for system C (three antennas); and 56.0 cm(3), 0.64, and 40.9 mm, respectively, for system D. Systems A (mean volume, 52.4 cm(3) ± 4.5 [standard deviation]) and B (39.4 cm(3) ± 1.7) reach large ablation zones with 5-minute ablation. CONCLUSION The largest ablation zone is obtained with systems B and C (three antennas) under maximum recommended ablation duration and with system A under short ablation time. The most spherical zone is obtained with system C (three antennas).

[1]  Hui-Xiong Xu,et al.  Liver cancer: increased microwave delivery to ablation zone with cooled-shaft antenna--experimental and clinical studies. , 2007, Radiology.

[2]  Christopher L Brace,et al.  High-powered microwave ablation with a small-gauge, gas-cooled antenna: initial ex vivo and in vivo results. , 2012, Journal of vascular and interventional radiology : JVIR.

[3]  Christopher L Brace,et al.  Radiofrequency and microwave ablation of the liver, lung, kidney, and bone: what are the differences? , 2009, Current problems in diagnostic radiology.

[4]  Ping Liang,et al.  Comparison of ablation zone between 915- and 2,450-MHz cooled-shaft microwave antenna: results in in vivo porcine livers. , 2009, AJR. American journal of roentgenology.

[5]  Christopher L Brace,et al.  Microwave tumor ablation: mechanism of action, clinical results, and devices. , 2010, Journal of vascular and interventional radiology : JVIR.

[6]  James Sayre,et al.  Influence of large peritumoral vessels on outcome of radiofrequency ablation of liver tumors. , 2003, Journal of vascular and interventional radiology : JVIR.

[7]  D E Dupuy,et al.  Image-guided radiofrequency tumor ablation: challenges and opportunities--part I. , 2001, Journal of vascular and interventional radiology : JVIR.

[8]  P. Ghaneh,et al.  Microwave ablation of ex vivo human liver and colorectal liver metastases with a novel 14.5 GHz generator , 2012, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[9]  L Solbiati,et al.  Large-volume tissue ablation with radio frequency by using a clustered, internally cooled electrode technique: laboratory and clinical experience in liver metastases. , 1998, Radiology.

[10]  F. Lee,et al.  Radiofrequency versus microwave ablation in a hepatic porcine model. , 2005, Radiology.

[11]  C. Brace,et al.  Microwaves create larger ablations than radiofrequency when controlled for power in ex vivo tissue. , 2010, Medical physics.

[12]  A. Stewart,et al.  The National Cancer Data Base report on treatment patterns for hepatocellular carcinomas , 2000, Cancer.

[13]  Lei Feng,et al.  Internally cooled antenna for microwave ablation: results in ex vivo and in vivo porcine livers. , 2008, European journal of radiology.

[14]  Christopher L Brace,et al.  Microwave ablation versus radiofrequency ablation in the kidney: high-power triaxial antennas create larger ablation zones than similarly sized internally cooled electrodes. , 2009, Journal of vascular and interventional radiology : JVIR.

[15]  S Nahum Goldberg,et al.  Microwave ablation: results with a 2.45-GHz applicator in ex vivo bovine and in vivo porcine liver. , 2006, Radiology.

[16]  William W Mayo-Smith,et al.  Microwave ablation: principles and applications. , 2005, Radiographics : a review publication of the Radiological Society of North America, Inc.

[17]  Carlo Bartolozzi,et al.  Early-stage hepatocellular carcinoma in patients with cirrhosis: long-term results of percutaneous image-guided radiofrequency ablation. , 2005, Radiology.

[18]  E F Halpern,et al.  Percutaneous radio-frequency ablation of hepatic metastases from colorectal cancer: long-term results in 117 patients. , 2001, Radiology.

[19]  Christopher L Brace,et al.  High-powered gas-cooled microwave ablation: shaft cooling creates an effective stick function without altering the ablation zone. , 2012, AJR. American journal of roentgenology.

[20]  Philippe L Pereira,et al.  Radiofrequency ablation: in vivo comparison of four commercially available devices in pig livers. , 2004, Radiology.

[21]  P. Liang,et al.  Comparison of temperature curve and ablation zone between 915- and 2450-MHz cooled-shaft microwave antenna: results in ex vivo porcine livers. , 2012, European journal of radiology.

[22]  Fangyi Liu,et al.  A comparison of microwave ablation and bipolar radiofrequency ablation both with an internally cooled probe: results in ex vivo and in vivo porcine livers. , 2011, European journal of radiology.

[23]  Christopher L Brace,et al.  Pulmonary thermal ablation: comparison of radiofrequency and microwave devices by using gross pathologic and CT findings in a swine model. , 2009, Radiology.

[24]  T. Tang,et al.  Comparison of microwave ablation and multipolar radiofrequency ablation, both using a pair of internally cooled interstitial applicators: Results in ex vivo porcine livers , 2011, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[25]  P. Liang,et al.  Prognostic factors for survival in patients with hepatocellular carcinoma after percutaneous microwave ablation. , 2005, Radiology.

[26]  Christopher L Brace,et al.  Microwave ablation with multiple simultaneously powered small-gauge triaxial antennas: results from an in vivo swine liver model. , 2007, Radiology.

[27]  W. Fan,et al.  Comparison of microwave ablation and multipolar radiofrequency ablation in vivo using two internally cooled probes. , 2012, AJR. American journal of roentgenology.

[28]  P. Liang,et al.  Comparison of percutaneous 915 MHz microwave ablation and 2450 MHz microwave ablation in large hepatocellular carcinoma , 2010, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[29]  D. W. van der Weide,et al.  Multiple-Antenna Microwave Ablation: Spatially Distributing Power Improves Thermal Profiles and Reduces Invasiveness. , 2009, Journal of interventional oncology.

[30]  David M. Mahvi,et al.  Hepatic Microwave Ablation With Multiple Antennae Results in Synergistically Larger Zones of Coagulation Necrosis , 2003, Annals of Surgical Oncology.

[31]  Christopher L Brace,et al.  Tissue contraction caused by radiofrequency and microwave ablation: a laboratory study in liver and lung. , 2010, Journal of vascular and interventional radiology : JVIR.

[32]  G. Gravante,et al.  Microwave ablation of the liver: a description of lesion evolution over time and an investigation of the heat sink effect , 2011, Pathology.