A New Velocity Estimator for Color Flow Mapping

Recently, real-time blood flow imaging became possible thanks to the development of a velocity estimator based on the phase-shift measurement of the successive echoes obtained from moving blood [ I]. However, this method suffers from the well known limitations of pulse-Doppler instruments. These drawbacks are mainly the conflict between velocity precision and axial resolution requirements, and the velocity limitation due to the aliasing phenomenon. In this paper, a new principle for velocity estimation, based on time domain correlation [21, is shown to overcome these problems. A simplified version of the technique using only I bit signals has been derived. This processing scheme has been optimized through extensive computer simulations. Experiments carried out on recorded in-vivo data, have confirmed the feasibility of measuring velocity profiles accurately, without the high velocity limitation (aliasing). Moreover, the possibility of obtain instantaneous and accurate velocity profiles by processing a limited number of echo response (about IO A-lines) should provide new potential modalities for clinical application of ultrasound.