Simulation of an acoustically excited bubble near a simulated ‘‘cell.’’

A variety of independent studies have reported increased bioeffects such as hemolysis and hemorrhage induced by high-intensity ultrasound when ultrasound contrast agents are present. Therefore, to better understand the role of cavitation, one-, two-, and three-dimensional models have been developed to investigate the interactions between ultrasonically excited bubbles and model ‘‘cells.’’ First, a simple one-dimensional model based on the Rayleigh–Plesset equation was used to estimate upper bounds for strain, strain rate, and areal expansion of a simulated red blood cell. Then, two- and three-dimensional boundary element models were developed (with DynaFlow Inc.) to obtain simulations of asymmetric bubble dynamics in the presence of rigid and deformable spheres. A spherical ‘‘cell’’ near an ultrasonically excited bubble was modeled using Tait’s equation of state for water, surrounded by a ‘‘membrane’’ with surface tension that increased linearly with areal expansion. The effect of a nearby ‘‘cell’’ on bubble response, the resulting pressure field around the ‘‘cell,’’ and ‘‘cell’’ membrane tensions were investigated. Preliminary results were compared with critical values for hemolysis reported in the literature. [Work supported by NIH.]