High intensity focused ultrasound (HIFU) ablation of porous liver: Numerical analysis of heat transfer and hemodynamics

Abstract

In the present study, the influence of the liver vascular bed on heat transfer in a tumor located close to the hepatic artery and exposed to high intensity focused ultrasound (HIFU), is studied numerically. For this purpose, an acoustics-thermal-fluid coupling model based on the porous media theory under the local thermal non-equilibrium assumption is used to calculate the temperature field in the tumor, porous liver, and the hepatic artery. Different generations of the liver vasculature including arterial branches, terminal arterial branches, terminal veins and venous branches are examined at different porosities (the volume fraction of the vasculature). It is found that the liver vasculature and the porosity have a considerable cooling effect on HIFU ablation efficacy and treatment planning. Also, it is shown that the terminal arterial branches have the most cooling effect because of their high blood velocity and heat transfer surface area. It is demonstrated that this effect is significant so that some cancerous cells remain viable near the tumor surface and therefore, some approaches should be adopted to ablate the tumor completely. Finally, the results show the importance of using local thermal non-equilibrium assumption to study the heat transfer in different generations of the liver vasculature.