Flow and heat transfer through a porous tumor during high-intensity focused ultrasound

Abstract

High-intensity focused ultrasound (HIFU) represents a non-invasive approach for localized treatment, wherein focused ultrasound waves are applied to specific tissues. However, accurately targeting the HIFU ablation area is still a challenge. The difference in the physical properties of the tumor being treated, compared to normal tissue, particularly, porosity, is an essential aspect that may influence the effectiveness of treatment. This study investigated the impact of tumor porosity, acoustic operating frequency, and the tumor acoustic absorption coefficient on fluid flow and temperature distribution in both the porous tumor and surrounding tissue during HIFU exposure using numerical models. Furthermore, the study examined the differences in porosity between normal and tumor tissues and the resulting phenomena. To determine the acoustic pressure, flow velocity, and temperature distributions in the porous tumor during HIFU treatment, researchers have employed numerical modeling to calculate acoustic wave propagation, fluid flow, and heat transfer processes. This study indicates that the maximal temperature increase might not always necessarily occur at the acoustic pressure focus, particularly, if the tumor does have a higher porosity than the neighboring normal tissue. This was because the flowing fluid of the tumor and adjacent tissues had a substantial impact on the strong convection in the focus area. These findings highlight the significance of this study in terms of precisely localizing the HIFU ablation target region and ensuring minimal thermal injury to the surrounding healthy tissue.