正常人和脑梗死患者颈动脉血流超声多普勒时频分析

目的：分别对正常人和脑梗死患颈动脉血流超声多普勒时频分析，为临床应用提供参考资料。方法：检测正常人和脑梗患（大多有颈动脉粥样硬化斑块）的颈动脉多普勒血流时频谱，以其峰值频率（fmax)，模式频率（fmode)，平均频率（fmean)，低值频率（fmin)，重脉波频率（fp)和频弥散宽度（fw)为定量指标。结果：正常人颈动脉血流信号时频谱的fmax,fmean和fmode曲线在一个心动周期中具有总体相似的形状，相互嵌套，其中收缩期的fmax最高，均大于3kHz,fmin最低不低于1kHz，脑梗死患颈动脉时频谱的fmax与fmean和fmode两曲线分开，fmax减低（＜3kHz)，fp消失，舒张末期fmin减低显（均低于0．5kHz)，结论：颈动脉多普勒血流时频分析及所遴选的定量指标对颈动脉粥样硬化斑块十分敏感，可供诊断试验，且可集成在便携式计算机里，适用于社区人群中筛选易中风病变个体。

Time-frequence analysis of carotid flow doppler signal in normal controls and cerebral infarction patients

Objective: To analyze time frequence of carotid flow Doppler signal of normal and cerebral infarction cases, providing reference for clinical applications. Methods: Time frequence spectrums of carotid flow Doppler signal of normal persons and of cerebral infarction cases (mostly with carotid atheromatous plaque) were detected. The peak frequence or envelope ( f max ), the mode frequence or the frequence with the greatest power ( f mode ), the mean frequence ( f mean ), the lowest frequence or the mean frequence in end diastolic phase ( f min ), duplicate pulse frequence or the frequence at the second duplicate peak ( f p) and spectral width or the time width at the half of the peak frequence ( f w) were taken as quantity indexes. Results: For normal persons, the frequence plots was a general uniformity of the shape of the frequence envelope throughout the cardiac cycle with similar values, f max in systole >3 kHz and f min > 1 kHz at least; For the cerebral infarction cases with carotid atheromatous plaque, the frequence plots for f max , f mode and f mean were separated throughout the cardiac cycle, f max in systole <3 kHz, duplicate pulse frequence disappeared and, as a significant feature, f min <0.5 kHz for every case. Conclusion: Time frequence analysis of carotid flow Doppler signal and quantity indexes selected by us are highly sensitive to abnormal cases with carotid atherosclerosis plaque and can be used as a diagnostic test. In addition, because these methods can be easily assembled in a notebook computer, they are especially suitable for screening individuals with the risk of stroke from the large population in communities.