Differentiation of moving scatterers with different velocities using trapezoid filter and pulse echo ultrasound

A trapezoid filter is introduced to map Doppler signals to spectral lines that associate to different velocities of scatterers. The filter completely rejects frequencies outside of a trapezoid area in the two-dimensional Fourier domain of Doppler RF signals. A three-dimensional Doppler image (or a movie of a two-dimensional image) with dimensions of location, Doppler spectrum, and time, can be obtained by listing the spectral lines along the beam axis. Gated integration of the Doppler image produces a coded map showing moving scatterers with different velocities. Experiments were performed using a peripheral vascular Doppler flow phantom. The method successfully differentiated the scatterers with different velocities at 29.8 cm/s and 14.6 cm/s. This new approach has potential for characterizing moving scatterers having different velocities within a sample volume.