Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan, China.
IEEE Trans Ultrason Ferroelectr Freq Control. 2010 Jan;57(1):203-13. doi: 10.1109/TUFFC.2010.1399.
A novel approach based on continuous wave (CW) Doppler ultrasound and the Hilbert-Huang transform with end-effect restraint by mirror extending is proposed to assess arterial distension. In the approach, bidirectional Doppler signals were first separated using the phasing-filter technique from the mixed quadrature Doppler signals, which were produced by bidirectional blood and vessel wall movements. Each separated unidirectional signal was decomposed into intrinsic mode functions (IMFs) using the empirical mode decomposition with end effect restraint by mirror extending algorithm, and then the relevant IMFs that contribute to the vessel wall components were identified. Finally, the displacement waveforms of the vessel wall were calculated by integrating its moving velocity waveforms, which were extracted from the bidirectional Hilbert spectrum estimated from the identified wall IMFs. This approach was applied to simulated and clinical Doppler signals from normal common carotid arteries (CCAs). In the simulation study, the estimated wall moving velocity and displacement waveforms were compared with the theoretical ones, respectively. The mean and standard deviation of the root-mean-square errors between the estimated and theoretical wall distension of the 30 realizations was 4.2 +/- 0.4 microm. In the clinical study, peak-to-peak distension was extracted in a subject and then averaged over 15 cardiac cycles, resulting in 603 +/- 22 microm. The mean and standard deviation of the CCA distension averaged over the experimental measurements of 12 healthy subjects gave the result of 620 +/- 154 microm. The clinical results were in agreement with those measured by using the multigate Doppler ultrasound and echo tracking systems. The results show that based on the CW Doppler ultrasound, the proposed approach is practical for extracting arterial wall peak-to-peak distension correctly and could be an alternative method for the vessel wall distension estimation.
一种基于连续波（CW）多普勒超声和希尔伯特-黄变换的新方法，通过镜像扩展来抑制端效应，用于评估动脉扩张。在该方法中，首先使用相位滤波技术从混合正交多普勒信号中分离双向多普勒信号，该信号由双向血流和血管壁运动产生。每个分离的单向信号都使用具有镜像扩展端效应约束的经验模态分解（EEMD）分解为固有模态函数（IMF），然后识别出与血管壁分量相关的相关 IMF。最后，通过从所识别的壁 IMF 估计的双向希尔伯特谱中提取其运动速度波形，并对其进行积分，计算血管壁的位移波形。该方法应用于正常颈总动脉（CCA）的模拟和临床多普勒信号。在模拟研究中，分别将估计的壁运动速度和位移波形与理论值进行比较。30 次实现中估计壁扩张与理论壁扩张的均方根误差的平均值和标准差为 4.2±0.4μm。在临床研究中，从一个受试者中提取峰峰值扩张，然后在 15 个心动周期上平均，得到 603±22μm。12 名健康受试者的实验测量平均 CCA 扩张的平均值和标准差为 620±154μm。临床结果与使用多门多普勒超声和回声跟踪系统测量的结果一致。结果表明，基于 CW 多普勒超声，该方法可用于正确提取动脉壁的峰峰值扩张，是血管壁扩张估计的一种替代方法。
