In order to map blood velocity in small regions near the transducer, we evaluate the performance of the wideband maximum likelihood (WMLE) strategy and infinite impulse response (IIR) filters for blood velocity estimation with a transducer center frequency of 38 MHz. Using a short transmitted pulse and the narrow lateral beam width obtained using this frequency, we show that velocities smaller than 1 mm/s can be estimated reliably. In addition, using both changes in the location and magnitude of the peak of the RF correlation, vessels as small as 40 /spl mu/m can be visualized in the RF signal and distinguished from stationary tissue. The experimental system also provides the opportunity to examine changes in flow and in the vessel wall over a cardiac cycle.
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机译：为了映射换能器附近小区域的血流速度，我们评估了换能器中心频率为38 MHz的宽带最大似然（WMLE）策略和无限冲激响应（IIR）滤波器的血流速度估计性能。使用短发射脉冲和使用此频率获得的窄横向波束宽度，我们表明可以可靠地估计小于1 mm / s的速度。此外，利用RF相关峰的位置和幅度的变化，可以在RF信号中可视化小至40 / splμm/ m的血管，并将其与静止组织区分开。实验系统还提供了检查心动周期内血流和血管壁变化的机会。
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