Thermal Characteristics of Microwave Ablation in the Vicinity of an Arterial Bifurcation

Abstract

The objective of this research was to reveal the thermal characteristics of microwave ablations in the vicinity of an arterial bifurcation. The temperature distribution after microwave heating of a liver-like material with the close presence of an arterial bifurcation was simulated using the finite element method. Coupled fluid flow and solid heat transfer were taken into consideration, and a three-dimensional analysis was performed. The experimentally determined SAR (specific absorption rate) generated by the absorption of microwaves in liver-like material was used in the analysis instead of utilizing electromagnetic calculations. Several different tests of time-controlled ablations with varying distances between the microwave antenna and the bifurcation were performed, and the detailed temperature distributions near the bifurcation were obtained. The interaction between the recirculation flow in the bifurcation and the heat transfer in the surrounding tissue makes the temperature distribution near the bifurcation complicated. Most importantly, after a period of continuous heating with constant microwave output power, the maximum temperatures caused by the ablation did not always increase with the distance between the antenna and the bifurcation. It can be concluded that inadequate ablations can be the result not only of a close distance between the antenna and the blood vessel, but also of complicated blood flow, in large vessels whose structure causes recirculation flow.