Thompson R S, Trudinger B J, Cook C M
Ultrasound Med Biol. 1986 Nov;12(11):845-54. doi: 10.1016/0301-5629(86)90002-5.
Umbilical artery Doppler recordings in both normal pregnancy and cases of fetal growth failure were processed by computer. Representative waveforms for the maximum velocity, mean velocity and first moment were obtained after ensemble averaging and correction for thump filtering. The same set of indices, which included the AB ratio, pulsatility index, rising slope and relative flow rate index, were calculated for each of the waveforms. The results were compared to identify differences which might arise in clinical practice if a waveform other than the usual (maximum velocity) was used. The ratio of the mean to the maximum velocity, which gives an indication of the velocity profile, was shown to be very error prone. The reproducibility of the mean velocity and first moment indices was inferior to that of the maximum velocity indices. The results from the different waveforms were highly correlated for normals for most indices. However, in the growth retarded group there was a tendency for the mean velocity and first moment indices to classify as normal studies classified as abnormal by the maximum velocity index. The values of indices derived from the first moment waveform were generally larger than the maximum and mean velocity values. For the relative flow rate index, where results were often different to the general trend, the values were more nearly equal.
正常妊娠和胎儿生长受限病例的脐动脉多普勒记录均由计算机处理。在进行总体平均和剔除脉冲滤波校正后，获得了最大速度、平均速度和一阶矩的代表性波形。针对每个波形计算了同一组指标，包括A/B比值、搏动指数、上升斜率和相对流速指数。对结果进行比较，以确定在临床实践中如果使用不同于通常的（最大速度）波形可能出现的差异。平均速度与最大速度之比可反映速度分布情况，但该比值极易出错。平均速度和一阶矩指标的可重复性低于最大速度指标。对于大多数指标，不同波形的结果在正常组中高度相关。然而，在生长受限组中，平均速度和一阶矩指标倾向于将最大速度指标分类为异常的研究归类为正常。从一阶矩波形得出的指标值通常大于最大速度和平均速度值。对于相对流速指数，其结果往往与总体趋势不同，各值更为接近。
