Blood Velocities Estimation using Ultrasound

This thesis consists of two parts. In the rst part, the iterative data-adaptive BIAA spectral estimation technique was extended to estimate lateral blood velocities using ultrasound scanners. The BIAA method makes no assumption on samples depth or sampling pattern, and therefore allows for transmission in duplex mode imaging. The technique was examined on a realistic Field II simulation data set, and showed fewer spectral artifacts in comparison with other techniques. In the second part of the thesis, another common problem in blood velocity estimation has been investigated, namely strong backscattered signals from stationary echoes. Two methods have been tested to examine the possibility of overcoming this problem. However, neither of these methods resulted in a better estimation of the blood velocities, most likely as the clutter characteristics in color ow images vary too rapidly to allow for this form of models. This might be a result of the non-stationary tissue motions which could be caused by a variety of factors, such as cardiac activities, respiration, transducer/patient movement, or a combination of them