Allard L, Langlois Y E, Durand L G, Roederer G O, Cloutier G
Laboratoire de Génie Biomédical, Institut de Recherches Cliniques de Montréal, Québec, Canada.
Med Biol Eng Comput. 1992 May;30(3):267-76. doi: 10.1007/BF02446964.
The objective of the present study was to analyse the effect of averaging Doppler blood flow signals in lower limb arteries on amplitude and feature variabilities. Doppler signals recorded in 41 iliac and 35 superficial femoral arteries having different categories of stenosis were averaged over 1-15 cardiac cycles. Based on the relative decreasing rate of an index of variability, results indicated that amplitude variability of the spectrograms was exponentially reduced to 30, 6 and 1 per cent when averaging five, ten and 15 cardiac cycles, respectively. Nine diagnostic features were extracted from Doppler spectrograms and their variations from one cardiac cycle to the next quantified. Based on the relative decreasing rate of these variations, results indicated that feature variability was exponentially reduced to 30, 4 and 1 per cent when averaging five, ten and 15 cardiac cycles, respectively. The effect of averaging on the discriminant power of the features to separate the different categories of stenosis was also investigated by performing t-test analyses. Results showed that averaging between five and ten cardiac cycles provided the better discriminant power for most cases, whereas averaging over more than ten cardiac cycles was of little benefit. Based on the spectral analysis technique used in the present study, we conclude that averaging over ten cardiac cycles is sufficient for the analysis of Doppler spectrograms recorded in the lower limbs.
本研究的目的是分析下肢动脉多普勒血流信号平均化对幅度和特征变异性的影响。对41条髂动脉和35条股浅动脉记录的、具有不同狭窄类别的多普勒信号在1至15个心动周期内进行平均。基于变异性指数的相对下降率，结果表明，当分别平均5个、10个和15个心动周期时，频谱图的幅度变异性分别指数下降至30%、6%和1%。从多普勒频谱图中提取九个诊断特征，并对其从一个心动周期到下一个心动周期的变化进行量化。基于这些变化的相对下降率，结果表明，当分别平均5个、10个和15个心动周期时，特征变异性分别指数下降至30%、4%和1%。还通过进行t检验分析研究了平均化对特征区分不同狭窄类别的判别能力的影响。结果表明，在大多数情况下，平均5至10个心动周期具有更好的判别能力，而平均超过10个心动周期则益处不大。基于本研究中使用的频谱分析技术，我们得出结论，平均10个心动周期足以分析下肢记录的多普勒频谱图。
