Electrical potentials in bone induced by ultrasound propagation

Abstract

Bone with complex geometry is hard, heterogeneous and anisotropic tissue, which makes ultrasound diagnosis very difficult. Therefore, the simulation of wave propagation is often performed to understand the complicated wave propagation in bone, where we find solid-liquid coexisting conditions. In addition to the diagnosis, one of the recent topics of bone studies are ultrasound fracture healing. The low intensity pulsed ultrasound (LIPUS) is popular as a fracture treatment technique in the field of orthopedic surgery, although how bones detect high frequency ultrasound is still under discussion. In this study, we focus on the weak piezoelectricity of bone as one of the key properties for the LIPUS treatment. According to the piezoelectric finite difference time-domain (PE-FDTD) method, we have investigated ultrasound propagation and generation of electrical potentials in bone. First, we verified the PE-FDTD method by comparing the simulated electric fields with the experimental data obtained by an ultrasound receiver using bone as the piezoelectric element. Next, we have tried to understand the wave propagation and generation in a real bone model (the radius of a 66-year-old woman). The generation of electrical potentials in the cancellous bone was also studied by simulation and experiments. The use of human bone to fabricate a model was permitted by the ethical committee at Doshisha University.