Theoretical Modeling for Hepatic Microwave Ablation~!2009-10-21~!2009-12-30~!2010-02-04~!

Abstract

Thermal tissue ablation is an interventional procedure increasingly being used for treatment of diverse medical conditions. Microwave ablation is emerging as an attractive modality for thermal therapy of large soft tissue targets in short periods of time, making it particularly suitable for ablation of hepatic and other tumors. Theoretical models of the ablation process are a powerful tool for predicting the temperature profile in tissue and resultant tissue damage created by ablation devices. These models play an important role in the design and optimization of devices for microwave tissue ablation. Furthermore, they are a useful tool for exploring and planning treatment delivery strategies. This review describes the status of theoretical models developed for microwave tissue ablation. It also reviews current challenges, research trends and progress towards development of accurate models for high temperature microwave tissue ablation.

Real‐Time Internal Steam Pop Detection during Radiofrequency Ablation with a Radiofrequency Ablation Needle Integrated with a Temperature and Pressure Sensor: Preclinical and Clinical Pilot Tests

“…The heat measurements were further utilized to simulate the heat transfer in the model of human hepatic tissue. The heat transfer in the biological medium was calculated based on the following Penne's equation [ 27 , 28 ] where ρ , c , k , T , Q, Q p , and Q m are the mass density, specific heat capacity, thermal conductivity, temperature, generated Joule heat, heat loss due to blood perfusion in the tissue, and generated metabolic heat, respectively. The heat Q p induced by the microvascular blood flow maintains the temperature of the tissue to the body temperature, and it can be further modeled as follows where ω b , c b , and T b are the blood perfusion rate, specific heat capacity of the blood, and temperature of the blood, respectively.…”

How large is the periablational zone after radiofrequency and microwave ablation? Computer-based comparative study of two currently used clinical devices

“…The MWA input power was specified as a coaxial port boundary condition at the top of the antenna and in RFA a constant voltage was set at the electrode boundaries. RFA was modeled with a typical clinical protocol based on 90 V pulses, while MWA was modeled with a constant power protocol of 60, 80 and 100 W values, which are typically used in clinical practice [ 21 , 22 ]. Note that these values are the power at the applicator input and may not coincide with those reported in clinical studies in which the reported power may be the MWA generator output power.…”

Evaluation of the performance of designed coaxial antennas for hyperthermia using simulation and experimental methods

“…Computer simulation is a quick, convenient and inexpensive tool for evaluating, isolating, and optimizing of promising devices for prototyping. [19][20][21][22][23][24] It is also an effective method in understanding the interactions between microwave energy and biological tissues. Finite element method (FEM) and finite-difference time-domain (FDTD) has been adopted in the antennas' geometry specifications and evaluation of heat transfer resulting from interactions of the microwave with biological tissues.…”

“…Theoretically, microwave energy propagation and absorption energy in tissue is governed by Maxwell's equations while Pennes' bio-heat equation governs the temperature profile in tissue during ablation and these have been discussed extensively in the literature. [19][20] To establish the study's validity, an experimental validation method that includes fabrication of the antenna from the selected coaxial cables, ex vivo experimentation and analysis of the obtained data must be compared with the simulation results. Thus, in this study, we employed computer simulation and experimental validation methods to evaluate the efficiency of two antennas fabricated from different semi-rigid coaxial cables meant for microwave ablation therapy.…”