Method and apparatus for a detection strength spatial filter in an

Abstract

An ultrasound imaging system where a location in the image has associated with it an amplitude and a velocity derived from a doppler shift assigns a detection strength to each location. Detection strength is a mapping from each possible combination of the amplitude and velocity into a scalar value that represents the likelihood that the velocity is not an artifact of the noise in the environment. The detection strength values are spatially filtered and then used to determine whether to accept or reject the measured velocity. A more optimistic filtering strategy for the measured velocity is now possible, and cooperates with a filtered detection strength to trim away suspicious regions in the image. The filtered detection strength signal can be used to compensate for unwanted side effects of other filtering done during the processing of the measured parameters. When the number of input bits exceeds the address space of a ROM filtering digital representations of measured parameters, the input values can be bifurcated into MSB's and LSB's, with the MSB's applied to the ROM as the address. The LSB's are sent to a MUX. The output value produced by each input combination can include two fields, one of which is the filtered or transformed value of the applied MSB's, and the other of which is a selector field. The selector field is pre-encoded to direct the MUX to select the LSB's that ought to be associated with the filtered or transformed value produced by the ROM in the other field. These recovered LSB's are then conjoined or otherwise used with that filtered or transformed value. The corduroy artifact of parallel flow operation can be removed by incorporating into the lateral detection strength filter a weighting scheme wherein the sum of the weights for the odd numbered radials in the filter's aperture equals the sum of the weights for the even numbered radials in the filter's aperture.