A Minimally Invasive Antenna for Microwave Ablation Therapies: Design, Performances, and Experimental Assessment

A new coaxial antenna for microwave ablation therapies is proposed. The antenna design includes a miniaturized choke and an arrowhead cap to facilitate antenna insertion into the tis sues. Antenna matching and the shape and dimension of the area of ablated tissue (thermal lesion) obtained in ex vivo conditions are evaluated both numerically and experimentally, finding an optimal agreement between numerical and experimental data. Results show that the antenna is well matched, and that it is able to produce a thermal lesion with an average length of 6.5 cm and an average diameter of 4.5 cm in ex vivo bovine liver when irradiates 60 W for 10 min. Finally, the dependence of antenna performances on possible changes in the antenna's structure is investigated, finding an optimal stability with respect to manufacturing tolerances and highlighting the fundamental role played by the antenna's choke.

[1]  James C. Lin,et al.  Antennas for Medical Therapy and Diagnostics , 2008 .

[2]  John G. Webster,et al.  An Optimal Sliding Choke Antenna for Hepatic Microwave Ablation , 2009, IEEE Transactions on Biomedical Engineering.

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

[4]  J. R. Carl,et al.  Microwave catheter design , 1998, IEEE Transactions on Biomedical Engineering.

[5]  P R Stauffer,et al.  Phantom and animal tissues for modelling the electrical properties of human liver , 2003, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[6]  Paolo Bernardi,et al.  Specific absorption rate and temperature elevation in a subject exposed in the far-field of radio-frequency sources operating in the 10-900-MHz range , 2003, IEEE Transactions on Biomedical Engineering.

[7]  Paolo Bernardi,et al.  A 915-MHz antenna for microwave thermal ablation treatment: physical design, computer modeling and experimental measurement , 2001, IEEE Transactions on Biomedical Engineering.

[8]  S. Pisa,et al.  Distribution of SAR and temperature elevation induced in a phantom by a microwave cardiac ablation catheter , 2004, IEEE Transactions on Microwave Theory and Techniques.

[9]  John G. Webster,et al.  Expanding the Bioheat Equation to Include Tissue Internal Water Evaporation During Heating , 2007, IEEE Transactions on Biomedical Engineering.

[10]  James C. Lin,et al.  Comparison of power deposition patterns produced by microwave and radio frequency cardiac ablation catheters , 1994 .

[11]  Deshan Yang,et al.  A review of coaxial-based interstitial antennas for hepatic microwave ablation. , 2006, Critical reviews in biomedical engineering.

[12]  John G. Webster,et al.  A floating sleeve antenna yields localized hepatic microwave ablation , 2006, IEEE Transactions on Biomedical Engineering.

[13]  S. Gedney.  An anisotropic perfectly matched layer-absorbing medium for the truncation of FDTD lattices , 1996 .

[14]  J.G. Webster,et al.  Design optimization of coaxial antennas for hepatic microwave ablation using genetic algorithms , 2008, 2008 IEEE Antennas and Propagation Society International Symposium.

[15]  H. H. Pennes.  Analysis of tissue and arterial blood temperatures in the resting human forearm. 1948. , 1948, Journal of applied physiology.

[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]  G. Gazelle,et al.  Thermal ablation therapy for focal malignancy: a unified approach to underlying principles, techniques, and diagnostic imaging guidance. , 2000, AJR. American journal of roentgenology.

[18]  M. Lazebnik,et al.  Ultrawideband temperature-dependent dielectric properties of animal liver tissue in the microwave frequency range , 2006, Physics in medicine and biology.

[19]  Christopher L. Brace,et al.  Temperature-dependent dielectric properties of liver tissue measured during thermal ablation: Toward an improved numerical model , 2008, 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[20]  C. Gabriel.  Compilation of the Dielectric Properties of Body Tissues at RF and Microwave Frequencies. , 1996 .

[22]  K. Yee.  Numerical solution of initial boundary value problems involving maxwell's equations in isotropic media , 1966 .

[23]  Guido Biffi Gentili,et al.  A coaxial antenna with miniaturized choke for minimally invasive interstitial heating , 2003, IEEE Transactions on Biomedical Engineering.

[24]  Michael C. Kolios,et al.  A theoretical comparison of energy sources--microwave, ultrasound and laser--for interstitial thermal therapy. , 1998, Physics in medicine and biology.

[25]  D. W. van der Weide,et al.  Microwave ablation with a triaxial antenna: results in ex vivo bovine liver , 2005, IEEE Transactions on Microwave Theory and Techniques.

[26]  Y. Chen,et al.  AutoMesh: an automatically adjustable, nonuniform, orthogonal FDTD mesh generator , 1999 .

[27]  P. Stauffer,et al.  Evaluation of microwave and radio frequency catheter ablation in a myocardium-equivalent phantom model , 1992, IEEE Transactions on Biomedical Engineering.

[28]  C. Diederich,et al.  Control of interstitial thermal coagulation: comparative evaluation of microwave and ultrasound applicators. , 2001, Medical physics.