超声成像中投影初始化壁滤波器的设计及实现

Design and Implementation of Projection-Initialized Wall Filter in Ultrasonic Imaging

壁滤波是彩色超声血流成像系统中的一项关键技术。如果不对来自静止和慢动组织的壁信号进行充分的滤除,低速血流很难被检测到,高速血流的估计也会有很大偏差,在各种壁滤波器中,基于投影初始化的无限冲击响应(IIR)壁滤波器具有过渡带窄和阻带衰减大等特性,性能优于其他的壁滤波器。然而目前对此类滤波器的研究仅限于理论层面,并没有发表切实可行的设计和实现方法。我们从实现和应用的角度,给出了一种新的投影初始化滤波器的设计和实现方案,将滤波器的实现转换为矩阵乘法操作,并在可编程逻辑器件上对其进行了实现。实验结果表明,这是一种简单有效的壁滤波器设计实现方法,性能优于传统的壁滤波器。

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 projectioninitialized IIR filter, and it is superior to conventional wall filters.