A quantitative comparison of theory and experiments on high intensity focused ultrasound (HIFU) induced heating in a vascularized tissue phantom

Abstract

High intensity focused ultrasound (HIFU) can be used to help control bleeding, both from individual blood vessels as well as from gross damage within the capillary bed. The dominant mechanism is rapid localized heating, and vascularity limits ones ability to elevate the temperature of blood vessels owing to convective heat transport. To better understand HIFU-induced heating in tissues with vascular structure, we employ a numerical scheme that couples models for ultrasound propagation, acoustic streaming, ultrasound heating, and blood cooling in Newtonian viscous media. We coordinate the theoretical effort with a series of in vitro experiments employing nonuniform flow-through tissue phantoms and designed to provide a ground truth verification of the model predictions. Calculated and measured results are compared over a range of parameter values (insonation pressure, insonation time, and flow rate). We demonstrate excellent agreement between predictions and measurements, and the simulations are extended to a study of the efficacy of HIFU in producing temperature elevations in large and small blood vessels. [Work supported by DARPA and the U.S. Army.]