Thermal characterization using fourier and non-fourier conduction during radiofrequency ablation of breast tumor

Abstract

Most of the numerical studies on radiofrequency ablation (RFA) utilize the Pennes bioheat equation to predict the temperature distribution and ablation volume post-treatment. The Pennes bioheat equation is based on the classical Fourier’s law of heat conduction which assumes infinite speed of heat propagation. However, in reality the propagation of thermal disturbance occurs usually at a finite speed with a delay ranging from 10 to 20 s in biological tissues. The present study investigates the differences between the Fourier and non-Fourier bioheat transfer models during RFA of breast tumor. A heterogeneous three-dimensional model of breast has been constructed based on the anatomical details available in the literature. The thermo-electric analysis has been performed using a finite element method (FEM)- based software by incorporating the coupled electric field distribution, the bioheat transfer equation, and the Arrhenius rate equation. The effect of temperature-dependent changes in electrical and thermal conductivities has been incorporated along with a non-linear model of blood perfusion. The numerical simulation results revealed that the Fourier model slightly overestimates the size of ablation volume produced during constant-voltage RFA of breast tumor as compared to non-Fourier conduction model. The effects of thermal relaxation time on the temperature distribution, input voltage requirement, and ablation volume have been studied for both the constant-voltage and temperature-controlled RFA. It has been found that the variation between temperature distributions and ablation volume obtained from the two approaches is more pronounced initially, and later decays with increase in treatment time.