The Performance of an Adaptive Rf-Domain Clutter Removal Filter
Ultrasound systems are widely used to visualize in real-time internal structures and blood flow velocity distributions. The latter are estimated from the received ultrasound radio frequency (RF) signals backscattered from moving red blood cells, using a mean frequency estimator. Since RF-signals contain not only scattering, but also reflections, reverberations and noise it is necessary to suppress the power of the reflections and/or reverberations (clutter removal) to estimate the temporal mean frequency of the signal component induced by scattering. Normally this is done with a static high-pass filter acting in the temporal direction with a fixed cut-off frequency. However, by using such a filter the time dependent aspect of the reflections is ignored. A more selective way is to use a band stop filter which adapts its rejection range to the mean frequency of the clutter. A great advantage of this adaptive filter (ADP-f) method is that the rejection range can be kept small.
KeywordsFiltration Expense Autocorrelation Settling Acoustics
Unable to display preview. Download preview PDF.
- Brands, P.J., Hoeks, A.P.G., Hofstra, L., and Reneman, R.S., 1995, A non-invasive method to estimate wall shear rate using ultrasound. Ultrasound Med. Biol. 21:171–185.Google Scholar
- De Jong, P.G.M., Arts, T., Hoeks, A.P.G., and Reneman, R.S., 1990, Determination of tissue motion velocity by correlation interpolation of pulsed ultrasonic echo signals. Ultrasonic Imaging. 12:84–98.Google Scholar
- Hoeks, A.P.G., Arts, G.J., Brands, P.J., and Reneman, R.S., 1993, Comparison of the performance of the RF cross-correlation and Doppler autocorrelation technique to estimate the mean velocity of simulated ultrasound signals. Ultrasound in Med. & Biol. 19:727–740.Google Scholar
- Hoeks, A.P.G., Van de Vorst, J.J.W., Dabekaussen, A., Brands, P.J., and Reneman R.S., 1991, An efficient algorithm to remove low frequency Doppler signals in digital Doppler systems. Ultrasonic Imaging. 13:135–144.Google Scholar
- Jensen, J.A., 1993, Stationary echo canceling in velocity estimation by time-domain cross-correlation. IEEE Trans, on Med. Imaging. 12:471–477.Google Scholar