AI 中文总结
研究扩频彩色多普勒超声，用简化数学模型解释其机制，研究离散时间梳状滤波器对多普勒频率估计精度的影响，比较与单平面波成像的有效性及对背景组织运动的敏感性，为改进其实际应用效用奠定基础。
AI 中文摘要
扩频彩色多普勒方法为单平面波彩色多普勒提供了一种替代方案，用于超快速血流成像，具有高奈奎斯特速度、高帧率和长集合。扩频图像通过在一系列方位角发射平面波来获取，每次重复时以不同随机顺序重复。平面波角度的随机化以不同方式调制聚焦和离焦回波，通过应用陷波梳状滤波器可抑制固定杂波而无需复合。本文用简化数学模型解释扩频方法机制，研究不同离散时间梳状滤波器实现对多普勒频率估计精度的影响，比较扩频与单平面波成像对多普勒信号源空间定位的有效性，并表征该方法对背景组织运动的敏感性。结果为进一步提高扩频方法在涉及非平稳杂波和生理相关流动模式的实际应用中的效用奠定了基础。
英文摘要
The spread-spectrum color Doppler method provides an alternative to single-plane-wave color Doppler for ultrafast blood-flow imaging with a high Nyquist velocity, high frame rate, and long ensembles. Spread-spectrum images are acquired by transmitting plane waves at a sequence of azimuth angles that is repeated multiple times in a different random order during each repetition. Randomization of the plane-wave angle modulates in-focus and off-focus echoes in distinct manners that enable stationary clutter to be suppressed without compounding by application of a notching comb filter. In this paper, a simplified mathematical model for the slow-time signal acquired with a sequence of plane waves is used to explain the mechanics of the spread-spectrum method, investigate the effect of different discrete-time comb filter realizations on the accuracy of the resulting Doppler frequency estimates, compare the effectiveness of spread-spectrum to single-plane-wave imaging for spatial localization of a Doppler signal source, and characterize the method's sensitivity to background tissue motion. The results establish a foundation to further improve the utility of the spread-spectrum method for practical applications involving non-stationary clutter and physiologically relevant flow patterns.
Comments21 pages, 15 figures
