Time delay estimation of discrete samples in ultrasound echo signals

The performances of various signal-processing applications in ultrasound medical imaging, including elastography, blood flow imaging, tissue velocity imaging, and acoustic radiation force impulse imaging, depend on their time-delay estimators. In this paper, we introduced a new class of time-delay estimator based on the tracking of individual samples using a continuous representation of the echo signal. Simulation results show that the sample tracking algorithms significantly outperformed the conventional window-based algorithms in terms of bias and jitter when individual estimates from the samples are averaged over the same window length. Simulations further showed similar performance to that of recently introduced spline-based continuous time-delay estimators only if all the samples in the window had identical delays. When the samples inside a window experienced different delays, sample tracking algorithms considerably outperformed the continuous delay estimators. In addition, the sample tracking algorithms showed to have much higher resolution and sensitivity when compared to all the other window-based techniques, including the continuous delay estimators.