Finite element characterization of the effect of flow on acoustic radiation force-induced waves in blood vessels

Ultrasound wave-based elastography has emerged as a promising technique for measuring the mechanical properties of blood vessels in vivo. It is well known that blood flow modulates the velocity of the symmetric natural pulse wave, but little has been reported about how it may affect the velocity of induced waves using acoustic radiation force (ARF). We used a fluid–structure interaction model in FEBio to study the effect of flow in elastic tubes after applying a simulated ARF. We varied the vessel wall Young’s modulus (E = 200, 400, and 600 kPa) and wall thickness (WT = 0.5, 1.0, and 1.5 mm) and applied mean flow rates of ±500, 1000, and 1500 mm/s with either parabolic or plug flow using an inviscid fluid model. Analysis of the phase velocities reveals a flow dependence which diminishes with frequency. Plug flow produced greater changes in dispersion curves than parabolic flow. Thinner tubes are more sensitive to flow than thicker tubes. Increasing E tends to increase sensitivity to flow slightly. These results indicate that flow rate may be an important variable to consider when estimating vascular properties from wave-based acquisitions.