Finite-Element Modeling of Tissue Responses to Focused Ultrasound With Different Intensities

Focused ultrasound (FUS) has been studied for different medical applications according to tissue responses to FUS with different intensities. At present, studies on responses to low-intensity focused ultrasound (LIFU) are mainly focused on mechanical responses and that to high-intensity focused ultrasound (HIFU) are focused on thermal responses. However, studies have shown that electrical responses can be produced by LIFU. In addition, modeling the complex energy conversion process of FUS from low to high intensity is challenging due to the computational complexity caused by multiphysics coupling and finite-element calculation. Based on the physical mechanism of each response to FUS with different intensities, a complete finite-element simulation platform is established to allow researchers to simulate not only the mechanical responses to LIFU and thermal responses to HIFU but also the electrical responses to LIFU. A multiphysics coupling method, which combines pressure acoustics field, solid mechanics field, electric currents field, and bioheat transfer field together, is used to enhance the matching among different physical fields and further reduce time consuming and improve simulation accuracy. The influences of ultrasound parameters and tissue properties on responses to FUS are discussed. Furthermore, experiments are implemented to validate this simulation platform. The simulation results are in good agreement with the theoretical derivation and experimental results as well as results reported previously, verifying the rationality of the simulation platform. This complete simulation platform is powerful for utilizing FUS with different intensities and can be further used for ultrasound elastography, acoustoelectric imaging, HIFU, and other related techniques.