Shear Wave Imaging Using Phase Modulation Component of Harmonic Distortion in Continuous Shear Wave Excitation

Abstract

An elasticity imaging method using continuous shear wave excitation (CSWE) is expected to be a safe and quantitative technique. A velocity map could be produced by propagating wave number spectrum analysis of a two-dimensional (2D) displacement map of shear wave propagation. However; the problems of accuracy and resolution have limited the reliability of this technique in medical diagnosis. In this paper, we propose a shear wave imaging system for reconstructing the spatial phase modulation component of shear wave propagation in order to obtain high-resolution images of continuous shear wave excitation. Shear wave local velocity, which is derived from the spatial differentation of the phase of complex displacement, is adopted as an imaging parameter. A fine texture-like pattern of the phase modulation component appears in the local velocity map, which gives precise information of small-amplitude phase modulation.

Shear wave mapping of skeletal muscle using shear wave wavefront reconstruction based on ultrasound color flow imaging

“…For example, the temperature rise and displacement in ARFI method were discussed, 19,20) Elastography was evaluated by numerical simulation and experiment. [21][22][23] Multi-parameter imaging was proposed by using multi-frequency shear wave excitation 24) and by considering shear wave nonlinear propagation. 25) We have proposed a novel imaging method for the imaging of a continuous shear wave.…”

Shear Wave Wavefront Mapping Using Ultrasound Color Flow Imaging

“…The actuator head and the ultrasonic probe are arranged on the same line to enable observation of the shear wave's wavefront perpendicular to the wave propagation direction. Figure 3 shows a comparison between the shear wave's wavefront observed using a shear wave imaging system based on small displacement measurement 15 and that observed using the proposed method. The shear wave's wavefront reconstruction method based on small displacement measurement is described in Appendix B.…”

“…Figure 3 shows a comparison between the shear wave’s wavefront observed using a shear wave imaging system based on small displacement measurement 15 and that observed using the proposed method. The shear wave’s wavefront reconstruction method based on small displacement measurement is described in Appendix B.…”

Echo speckle imaging of blood particles with high-frame-rate echocardiography

“…Thus far, many researchers have examined methods utilizing an echo speckle, which contains information on tissue structures for blood flow vector estimation, 23) the quantitative evaluation of liver fibrosis, 22,24) and shear wave velocity measurement for tissue elasticity imaging. [25][26][27] An echo speckle, which arises from blood echoes, translates between successive frames, i.e., the spatial feature of an echo speckle is preserved, when blood particles move in the same direction without changing their relative distance. The velocity vector of a slow blood flow in the left atrium has been calculated using the dynamic texture produced by strong backscattering.…”