Real-time acoustic radiation force impulse imaging

Acoustic Radiation Force Impulse (ARFI) imaging uses short duration acoustic pulses to generate and subsequently determine localized displacements in tissue. Time delay estimators, such as normalized cross correlation and phase shift estimation, form the computational basis for ARFI imaging. This paper considers these algorithms and the effects of noise, interpolation, and quadrature demodulation on the accuracy of the time delay estimates. These results are used to implement a real-time ARFI imaging system and in an ex vivo liver ablation study.