A real time displacement estimation algorithm for ultrasound elastography

• We develop a real time algorithm for tissue motion estimation for ultrasound elastography.
• Synthetic experiment proves our algorithm more robust when applied strain enlarges or Poisson's ratio increases.
• Both signal to noise ratio and contrast to noise ratio are much higher than those obtained using the previously published method at high strain level or tissue incompressibility case.
• Elasticity phantom and clinical data demonstrate excellent abnormity detectability of our algorithm.
• However, 3D displacement field and strain tensor estimation is needed when soft tissue is modeled as anisotropic and viscoelastic.

Motion tracking algorithms to derive the local displacement distribution inside soft tissue from ultrasonic radio frequency (RF) signals are critical for ultrasound-based techniques, especially for ultrasound elastography. Normally, there is a trade-off between precision and computational cost. In this study, we present a framework combined with block matching algorithm (BMA) and phase shift method with prior estimation (PSPE). BMA is first applied to the RF signals, the axial and lateral displacements obtained are then used as a prior estimates of the PS method to calculate a more precision axial displacements. The performance of the algorithm is evaluated with synthetic ultrasound RF data, and it is found that both SNRe and CNRe of our method are significantly higher than those of phase-shift as a prior estimation (PSPE) method. Elasticity phantom and clinical data are also used to verify the usefulness of our algorithm, respectively. The results show that our method is robust to image the complex tissue motions.

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