Quasi-omnidirectional shear wave generation using acoustic vortices for elastography

Ultrasound elastography is a reliable tool for medical diagnosis with the aim of finding pathologies that cause tissue stiffness irregularities. Currently, the most used techniques based on acoustic radiation force deform the tissue with a pulse in the direction of beam propagation resulting in linear momentum transfer, producing shear waves in the transverse direction of the beam. In this work we propose using focused acoustic vortices to transfer angular momentum. By twisting the tissue quasi-omnidirectional shear waves can be generated. The goal of this work is to show the first experimental evidence of angular momentum transfer from a vortex to a tissue-mimicking material, and apply this mechanism to improve ultrasound elastography.