An adaptive clutter rejection filter in ultrasound color flow imaging systems

In ultrasound color flow imaging systems, the imaging quality is highly influenced by the clutter originating from the vascular wall, stationary and slowly moving tissue. Moreover, in practice, relative motion between the probe held by doctor and the blood flow also induce the clutter along with blood flow. If there is not clutter rejection, the estimation value of low velocity blood flow will be inaccurate, and the CFM imaging quality will be poor. In this paper a new adaptive filtering scheme is introduced. In this scheme statistical theory is used to calculate the mean frequency and variance of clutter signal. The mean frequency is used to mix down the Doppler signal, and the variance determines the filter´s cut-off frequency. So it achieves the adaptability of the clutter rejection filter and improves the accuracy and flexibility of the ultrasound devices.