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首页> 外文期刊>Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on >Time-domain calculation of spectral centroid from backscattered ultrasound signals
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Time-domain calculation of spectral centroid from backscattered ultrasound signals

机译：背向散射超声信号频谱质心的时域计算

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摘要

Spectral centroid estimation from backscattered ultrasound RF signals is the preliminary step for quantitative ultrasound analysis in many medical applications. The traditional approach of estimating the spectral centroid in the frequency domain takes a long time because discrete Fourier transform (DFT) processing for each RF segment is required. To avoid this, we propose time-domain methods to estimate the spectral centroid in this paper. First, we derive the continuous- time-domain equations for the spectral centroid estimation using Parseval??s theorem and Hilbert transform theory. Then, we extend the method to the discrete-time domain to ease the implementation while maintaining the same accuracy as the calculation in the frequency domain. From the result, we observe that it is not practical to apply the discrete-time equations directly, because a high sampling rate is needed to approximate the time derivative in the discrete-time domain. Therefore, we also derive the feasible version of the discretetime equations using a circular autocorrelation function, which has no constraints on the sampling rate for real RF signals acquired from pulse-echo ultrasound systems. Simulation results using numerical phantoms show that the time-domain calculation is approximately 4.4 times faster on average than the frequency- domain method when the software??s built-in functions were used. The average estimation error compared with that of the frequency-domain method using DFT is less than 0.2% for the entire propagation depths. The proposed time-domain approach to estimate the spectral centroid can be easily implemented in real-time ultrasound systems.
机译：从背向散射的超声RF信号进行光谱质心估计是许多医学应用中定量超声分析的第一步。在频域上估计频谱质心的传统方法花费很长时间，因为需要对每个RF段进行离散傅里叶变换（DFT）处理。为避免这种情况，本文提出了一种时域方法来估计频谱质心。首先，我们使用Parseval定理和Hilbert变换理论推导用于谱质心估计的连续时域方程。然后，我们将该方法扩展到离散时域以简化实现，同时保持与频域中计算相同的准确性。从结果可以看出，直接应用离散时间方程是不切实际的，因为需要较高的采样率才能近似离散时间域中的时间导数。因此，我们还使用圆形自相关函数得出离散时间方程的可行版本，该函数对从脉冲回波超声系统获取的实际RF信号的采样率没有限制。使用数字体模的仿真结果表明，使用软件的内置函数时，时域计算平均比频域方法快约4.4倍。对于整个传播深度，与使用DFT的频域方法相比，平均估计误差小于0.2％。所提出的估计频谱质心的时域方法可以在实时超声系统中轻松实现。

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