Local Phase Velocity Based Imaging: A New Technique Used for Ultrasound Shear Wave Elastography

Abstract

Ultrasound shear wave elastography is an imaging modality for noninvasive evaluation of tissue mechanical properties. However, many current techniques overestimate a lesion's dimension or shape especially when small inclusions are taken into account. In this study we propose a new method called local phase velocity based imaging (LPVI) as an alternative technique to measure tissue elasticity. Two separate acquisitions with ultrasound push beams focused once on the left side and once on the right side of the inclusion were generated. A local shear wave velocity is then recovered in the frequency domain (for a single frequency or frequency band) for both acquired data sets. Finally, a two-dimensional shear wave velocity map is reconstructed by combining maps from two separate acquisitions. Robust and accurate shear wave velocity maps are reconstructed using the proposed LPVI method in calibrated liver fibrosis tissue mimicking homogeneous phantoms, a calibrated elastography phantom with stepped cylinder inclusions and a homemade gelatin phantom with ex vivo porcine liver inclusion. Results are compared with an existing phase velocity based imaging approach and a group velocity based method considered as the state-ofthe-art. Results from the phantom study showed that increased frequency improved the shape of the reconstructed inclusions and contrast-to-noise ratio between the target and background.

SHEAR-net: An End-to-End Deep Learning Approach for Single Push Ultrasound Shear Wave Elasticity Imaging

“…In this section, we present the results of our proposed SHEAR-net for both the simulation and experimental phantom data and also compare its performance with the most recent state-of-the-art algorithm: local phase velocity imaging (LPVI) [24].…”

“…The second category of methods for shear wave velocity estimation involves the frequency domain. These approaches use phase velocity estimated from the local maximum wave number, and two dimensional Fourier transformation on the time-space signal to estimate the phase velocity [24], [25]. In both categories of approaches, the number of ARF pushes make a difference in the quality of the reconstructed images as described in LPVI and CSUE [22], [24].…”

“…These approaches use phase velocity estimated from the local maximum wave number, and two dimensional Fourier transformation on the time-space signal to estimate the phase velocity [24], [25]. In both categories of approaches, the number of ARF pushes make a difference in the quality of the reconstructed images as described in LPVI and CSUE [22], [24]. Though current state-of-the-art is the LPVI technique, the efficacy of this algorithm largely depends on the window selection like other conventional approaches.…”

Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

“…Local phase velocity imaging (LPVI) [105,106] is another method that can produce a phase velocity map. The LPVI requires applying bandpass filters to obtain the maximal frequency range for the phase velocity.…”

Acoustic Radiation Force: A Review of Four Mechanisms for Biomedical Applications

“…Numerous other elastographic modalities using A-ARF were developed in the next decade. These modalities include but not limited to: SuperSonic Imaging [32], Harmonic Motion Imaging [33], crawling wave estimator [34], Shearwave Dispersion Ultrasound Vibrometry (SDUV) [35], Lamb wave dispersion ultrasound vibrometry (LDUV) [36], attenuation measuring ultrasound shear wave elastography (AMUSE) [37], Acoustic Radiation Force Induced Creep-Recovery [38], Local Phase Velocity Based Imaging [39], Viscoelastic Response (VisR) Imaging [40], Shear Wave Spectroscopy for quantification of tissue viscoelasticity [41], fractional derivative group shear estimation [42], reverberant shear wave fields for estimation of shear wave speed [43], twopoint frequency shift for shear wave attenuation measurement [44], and spatially-modulated ultrasound radiation force (STL-SWE/SMURF) [45]. A detailed description of the clinical applications of selected technologies based on mechanism A-ARF can be found in [24], [12].…”