Method and apparatus for adaptive wall filtering in spectral doppler ultrasound imaging

A method and an apparatus for adaptive wall (high-pass) filtering to remove low-frequency clutter in spectral Doppler I/Q data prior to FFT processing. The I/Q data is passed through a low-pass filter (26) which rejects the flow frequency components above the clutter frequency range. The total power of the low-pass filter output is then computed (28). A system noise model (30)is used to predict (32) the mean system noise power in the low-pass filter output. The predicted mean noise power provides a noise threshold to gage how much clutter power is present in the current FFT packet. If no significant clutter is present, then wall filter selection logic (36) will automatically select the lowest wall filter cutoff frequency stored in a filter coefficient LUT. If significant clutter power is present in the FFT packet, then the mean and variance of the clutter frequency over the FFT packet are estimated (34) and then input into the filter selection logic (36), which selects the most suitable filter cutoff for the current clutter signal.