Two-dimensional shear elasticity imaging using external mechanical vibration

Compared to ultrasound radiation force, mechanical vibration is capable of delivering larger motion into deep tissues. However, the propagation direction of the shear waves generated by such method can be complicated and unpredictable, which make it difficult to measure shear wave speed (c_s). In this study, we propose using multiple vibration sources to produce a multi-directional shear wave field, and calculating a two-dimensional (2D) c_s map based on cross-correlation after applying directional filtering to the field. The proposed method is tested using homogeneous and inclusion phantoms as well as in vivo liver in a healthy subject. Results show that the method has good penetration, boundary delineation, and consistent elasticity measurement.