心动周期性多普勒波形的平均方法

许多临床上有用的多普勒小以形都是随时产是变化的，但又近似于周期心动周期的周期信号。为准确估计这些多普靳波形，并提取主同灵敏度的特征参数，有必要对它们按心吉期进行平均。

Methods of averaging the Doppler waveforms over cardiac cycles

Many Doppler waveforms useful in clinic are time-varying, which can usuallybe regarded as periodic signals with the period equal to the cardiac cycle. To estimatethese waveforms with high resolution and to extract the high sensitivity characteristicindices, it is necessary to have the waveforms averaged over cardiac cycles. An outertrigger signal, such as that from ECG, can be used for synchronism ill the direct averagnmethod. Several methods in which only Doppler signals themselves are used, such as themathematical morphology, the wavelet transform and the auto-correlation, are describedin this paper. From analysis of the computer simulated and the in vivo Doppler signals,it is found that these methods can be used to average the Dopp1er waveforms. Amongthem, the auto-corre1ation method gives the best results.