Improving shear wave speed estimation precision in homogeneous media by tracking shear wave propagation in 3D using a real-time volumetric imaging transducer

A system capable of tracking radiation force induced shear wave propagation in 3D using ultrasound is presented. In contrast to existing systems, which use 1D array transducers, a 2D matrix array is used for tracking shear wave displacements. A HIFU piston is used for radiation force excitation. This system allows shear wave propagation in all directions away from the push to be observed, for the first time. It is shown that for a limit of 64 tracking beams and a given reconstruction kernel size, by placing the tracking beams at the edges of the kernel at multiple directions from the push, time-of-flight (TOF) shear wave speed (SWS) measurement uncertainty can theoretically be reduced by 40% compared to equally spacing the tracking beams within the kernel along a single plane, as is typical when using a 1D array for tracking. This was verified by simulation, and a reduction of 30% was experimentally observed on a homogeneous phantom.