AN AXIAL VELOCITY ESTIMATOR FOR ULTRASOUND BLOOD-FLOW IMAGING, BASED ON A FULL EVALUATION OF THE DOPPLER EQUATION BY MEANS OF A 2-DIMENSIONAL AUTOCORRELATION APPROACH
AN AXIAL VELOCITY ESTIMATOR FOR ULTRASOUND BLOOD-FLOW IMAGING, BASED ON A FULL EVALUATION OF THE DOPPLER EQUATION BY MEANS OF A 2-DIMENSIONAL AUTOCORRELATION APPROACH
复制标题
DOI：
10.1109/58.393110
复制
发表时间：
1995-07-01
影响因子：
3.6
通讯作者：
GILL, RW
中科院分区：
文献类型：
--
作者：
LOUPAS, T;POWERS, JT;GILL, RW
本文介绍了一种新的速度估计器，称为 2D 自相关器，它与传统的多普勒技术有两个不同之处：通过使用每个距离门位置的平均多普勒和平均 RF 频率的显式估计来评估多普勒方程来推导轴向速度值；并且，距离门内处理的 2D 性质（深度样本与脉冲传输），可以通过评估两个滞后处解调（基带）反向散射回波的 2D 自相关函数来计算估计器的输出，基于 2D 傅立叶变换的框架，提出了估计器的完整推导和数学描述，采用相同的框架来分析另外两个已建立的速度估计器（传统的 1D 速度估计器）以统一的方式使用自相关器和互相关器），并使用理论论证和实验结果来突出所有三种估计器的共同点。此外，通过广泛的模拟进行了彻底的性能评估，记录了许多因素（速度扩展、距离门长度、系综长度、噪声水平、传输带宽）的影响，并提供了对与各个算法相关的最佳参数和权衡的深入了解。总体而言，2D 自相关器在此处考虑的特定仿真条件下显示出最佳性能，其相对于互相关器的优越性仅限于低信噪比的情况，但是，2D 自相关器始终明显优于传统的 1D 自相关器。当与所提出的估计器的计算要求相关时，这些比较表明它将 2D 宽带时域技术的普遍较高性能与一维窄带相域速度估计器的复杂性相对适中。
This paper introduces a new velocity estimator, referred to as the 2D autocorrelator, which differs from conventional Doppler techniques in two respects: the derivation of axial velocity values by evaluating the Doppler equation using explicit estimates of both the mean Doppler and the mean RF frequency at each range gate location; and, the 2D nature (depth samples versus pulse transmissions) of processing within the range gate, The estimator's output can be calculated by evaluating the 2D autocorrelation function of the demodulated (baseband) backscattered echoes at two lags, A full derivation and mathematical description of the estimator is presented, based on the framework of the 2D Fourier transform, The same framework is adopted to analyze two other established velocity estimators (the conventional 1D autoeorrelator and the crosscorrelator) in a unifying manner, and theoretical arguments as well as experimental results are used to highlight the common aspects of all three estimators, In addition, a thorough performance evaluation is carried out by means of extensive simulations, which document the effect of a number of factors (velocity spread, range gate length, ensemble length, noise level, transmitted bandwidth) and provide an insight into the optimum parameters and trade-offs associated with individual algorithms. Overall, the 2D autocorrelator is shown to offer the best performance in the context of the specific simulation conditions considered here, Its superiority over the crosscorrelator is restricted to cases of low signal-to-noise ratios, However, the 2D autocorrelator always outperforms the conventional 1D autocorrelator by a significant margin, These comparisons, when linked to the computational requirements of the proposed estimator, suggest that it combines the generally higher performance of 2D broadband time-domain techniques with the relatively modest complexity of 1D narrowband phase-domain velocity estimators.