Design and implementation of projection-initialized wall filter in ultrasonic imaging

Wall filtering is a key technology in ultrasound color flow imaging system. Without efficient suppression of wall signal originating from stationary and moving tissue, low velocity blood flow cannot be measured, and the estimates of higher velocities will have a large bias. Among the various wall filters, the projection-initialized infinite impulse response (IIR) wall filter has narrow transition bandwidth and high stopband suppression ratio; it is superior to other wall filters. At present, the related literatures are only limited to theoretical research on this kind of filter, and no feasible design and implementation methods are reported. In this paper, a new design and implementation scheme for the projection-initialized filter is proposed, which transforms the filtering process to matrix multiplications. The proposed scheme is realized on programmable logic devices. Experimental results show that it is a simple and effective implementation method for projection-initialized IIR filter, and it is superior to conventional wall filters.