Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA.
Physiol Meas. 2011 Jan;32(1):51-64. doi: 10.1088/0967-3334/32/1/004. Epub 2010 Nov 19.
We investigated the utility of ICA for evaluation of fetal rhythm in five uncomplicated twin pregnancies and in five twin pregnancies complicated by fetal arrhythmia. Using objective and subjective criteria, we sought to determine how the signal-to-noise ratio, signal fidelity and interference rejection are affected when synthesizing the fetal signal using all the signal-containing ICA components (rank-p ICA) versus using the single dominant component (rank-1 ICA). The signal of each fetus was most commonly distributed over 1 or 2 ICA components, as previously observed in studies of singleton pregnancies; however, in 8 of 26 (31%) cases the signal of each fetus was distributed over 3, 4 or even 5 ICA components. Rank-1 ICA provided the highest SNR and interference rejection, but at the cost of reduced signal fidelity. Our results corroborate that in twin pregnancies, including twin pregnancies complicated by fetal arrhythmia, rank-1 ICA is very effective in isolating the QRS complexes of each fetus; however, it has some limitations when used for fetal rhythm evaluation due to signal distortion. Occasionally, rank-1 ICA completely separates the P-wave and the T-wave from the QRS complex, thus requiring the mixing of several ICA components to achieve acceptable signal fidelity.
我们研究了 ICA 在评价 5 例非复杂双胞胎妊娠和 5 例胎儿心律失常复杂双胞胎妊娠中的应用。使用客观和主观标准，我们试图确定在使用所有包含信号的 ICA 分量（秩-p ICA）和使用单个主导分量（秩-1 ICA）合成胎儿信号时，信号噪声比、信号保真度和干扰抑制如何受到影响。如先前在单胎妊娠研究中观察到的那样，每个胎儿的信号通常分布在 1 或 2 个 ICA 分量上；然而，在 26 例中的 8 例（31%）中，每个胎儿的信号分布在 3、4 甚至 5 个 ICA 分量上。秩-1 ICA 提供了最高的 SNR 和干扰抑制，但代价是降低了信号保真度。我们的结果证实，在双胞胎妊娠中，包括胎儿心律失常复杂的双胞胎妊娠中，秩-1 ICA 非常有效地分离每个胎儿的 QRS 复合体；然而，由于信号失真，它在用于胎儿节律评估时存在一些局限性。偶尔，秩-1 ICA 会完全将 P 波和 T 波与 QRS 复合体分离，因此需要混合几个 ICA 分量以达到可接受的信号保真度。
