Time-delay estimation is a widely used signal processing task in many areas of ultrasound medical imaging and the performance of many applications is highly dependent on the accuracy and efficiency of the time-delay estimates. Time-delay estimation determines the displacement between two ultrasound echo signals. In this thesis, we propose a new time-delay estimation algorithm, which generates a zero-crossing curve to compute the time-delay estimate between two ultrasound echo signals. A comparative study, using statistical analysis and quantitative measurement of image quality in simulated and experimental ultrasound elastography, was done to compare the performance of the proposed algorithm with other established algorithms, such as normalized cross-correlation (NCC) and sum squared differences (SSD). The results of comparison of various algorithms using signal-to-noise and contrast-to-noise ratios indicated that the new algorithm only marginally improved the quality of the images in ultrasound elastography. In addition, a novel strain map normalization method was implemented to enhance target visualization in ultrasound elastography by compensating for strain decay with depth.
A new algorithm for time-delay estimation in ultrasonic echo signals and a comparative study of its performance evaluation in ultrasound elastography imaging
