Models for the dynamical interaction of bubbles and blood vessels.

Abstract

An understanding of ultrasound contrast agent (UCA) microbubble dynamics in blood vessels is important for ultrasound imaging and therapy. Recent photographs of UCAs excited by high‐intensity ultrasound pulses in ex vivo vessels reveal unexpected phenomena. Strong bubble pulsations near the vessel wall induce contraction of the vessel that remains after bubble motion has subsided. Also, the bubble often translates toward the center of the vessel while forming a jet in the direction of translation. Three models describing the dynamics of a bubble in channels formed by elastic walls have been developed in an attempt to understand these phenomena. Two of the models describe a bubble between parallel elastic layers immersed in a viscous fluid. One incorporates bubble translation and aspherical bubble shape, which accounts for the onset of jetting, but is limited to incompressible fluids and layers with small shear moduli. The other accounts for fluid compressibility and arbitrary layer viscoelasticity, but is limited to stationary spherical bubbles. The third model is for a spherical bubble at an arbitrary but fixed location in a cylindrical viscoelastic tube. Comparisons between observed behavior and theoretical predictions will be presented and the relative merits of each model discussed. [Work supported by NIH DK070618.]