Hewlett-packard Company

Sydney M Karp

Raymond A Beaudin

Jerome F Witt

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.

Method and apparatus for a detection strength spatial filter in an

An asymmetric finite impulse response digital filter, typically used in an ultrasound imaging system, includes forward and reverse sections. In the forward section, a group of input data samples is multiplied by a set of filter coefficients in a forward order to provide first intermediate results. The first intermediate results are summed to provide a first output sample. In the reverse section, the group of input data samples is multiplied by the set of coefficients in a reverse order as compared with the forward section to provide second intermediate results. The second intermediate results are summed to provide a second output sample. The process is repeated to provide multiple first and second output samples. A signal estimation unit estimates a characteristic of the input data samples, such as the frequency of a Doppler ultrasound signal, based on the first and second output samples. The filter provides twice as many output samples as prior art filters for a given set of input data samples. The filter is preferably used as a clutter filter to remove low frequency clutter from a Doppler ultrasound signal.

Ultrasound imaging system using finite impulse response digital clutter

An adaptive flash rejection filter for a color flow imaging apparatus uses a flash strength identifier to make an initial determination of flash content. The identifier assigns a flash strength to each signal portion of a scan line according to a velocity component and a magnitude component of that signal portion. The number of flash strengths in a line which fall into a designated flash range are accumulated to arrive at an approximate measure of flash content. A filter arrangement uses the accumulated flash content to determine a proper flash rejection level for a line. An entire line of flash strengths and velocity measurements are stored in a line memory, which serves to delay those signals while the proper flash rejection level is being determined. The filter arrangement then receives the flash strengths and the velocity components, and inhibits an output of a velocity component if its corresponding flash strength exceeds the assigned flash rejection level. This serves to reject velocity components containing flash and prevent their processing by the color flow display circuitry.

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Reading, MA, United States of America

Sydney M Karp