Color flow processor having adaptive wall filter

Claim 1

A processor for color flow imaging of the velocity of scatterers flowing past slowly moving tissue, comprising: means for supplying basebanded signals derived from ultrasound reflected by the scatterers and by the tissue; a wall estimator for processing said basebanded signals to output a wall frequency signal representing an estimated mean Doppler frequency produced by the slowly moving tissue and a wall velocity signal representing an estimated velocity of the slowly moving tissue; mixing means for mixing said basebanded signal using said wall frequency signal so that the wall component is at DC and then outputting the mixed basebanded signals; and a flow estimator for processing said mixed basebanded signals and said wall velocity signal in an adaptive mode to output a flow velocity signal representing an estimated flow velocity of the scatterers which compensates for movement of the slowly moving tissue, wherein said wall estimator comprises: means for correlating basebanded signals to output signals representing first, second and third autocorrelation parameters; a processor for outputting signals representing wall velocity and a magnitude of a fourth autocorrelation parameter in response to receipt of said signals representing said first and second autocorrelation parameters from said correlating means; a first filter for receiving said signal representing wall velocity; means for outputting a signal representing wall frequency in response to receipt of the filtered wall velocity signal from said first filter; a variance divider for outputting a signal representing the wall variance in response to receipt of said signal representing said third autocorrelation parameter from said correlating means and said signal representing said magnitude of said fourth autocorrelation parameter from said processor; means for outputting a signal representing wall power; and threshold logic means for controlling operation of said first filter as a function of said wall variance signal or said wall power signal or a combination thereof.