The use of ultrasound in medicine is widespread, ranging from imaging in echocardiography to therapy, e.g., shock-wave lithotripsy for kidney stone treatment and histotripsy for pathogenic tissue ablation. In several of these procedures, pressure waves produce and/or interact with cavitation bubbles, whose dynamics and collapse may lead to tissue injury, unintentional or deliberate. This presentation summarizes our efforts to develop and use numerical modeling and high-fidelity simulations techniques to investigate cavitation dynamics in tissue-like media, with application to contrast-enhanced ultrasound and histotripsy. By considering simple model problems, we can identify mechanisms of ultrasound-induced cavitation in tissue. Numerical modeling of spherical bubble dynamics shows that the viscoelasticity of the medium strongly affects the growth, frequency and energy dissipation of the bubble oscillations, and may lead to previously unknown damage mechanisms. Numerical simulations of shock-bubble interaction demonstrate that the presence of individual cavitation bubbles amplifies the incoming pulse pressure and produce sufficient tension to generate cavitation in histotripsy.
Eric Johnsen has been an Assistant Professor of Mechanical Engineering at the University of Michigan since 2010. He received his BS from UCSB in 2001, and MS and PhD from Caltech in 2002 and 2008, respectively; he then spent two years as a post-doctoral fellow at the Center for Turbulence Research at Stanford. His research interests lie in the broad field of fluid mechanics, including multiphase flows and plasmas, turbulence, compressible flow and scientific computing. His group’s work finds applications in biomedical engineering, energy sciences, and aeronautical, automotive and naval engineering. He is the recipient of the NSF CAREER and ONR Young Investigator awards.
Date(s) - Nov 06, 2015
12:00 pm - 1:00 pm