Estimating uterine source current during contractions using magnetomyography measurements.
Estimating uterine source current during contractions using magnetomyography measurements.
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DOI：
10.1371/journal.pone.0202184
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
Nehorai A
中科院分区：
文献类型：
--
作者：
Zhang M;La Rosa PS;Eswaran H;Nehorai A
了解孕期宫缩电生理活动的子宫来源具有重要的科学意义和潜在的临床应用价值。在这项工作中，我们提出了一种方法，通过测量腹部表面的磁肌图(MMG)时间进程来估计子宫源电流。特别是，我们基于准静态麦克斯韦方程和一个现实的四室体导体建立了一个线性正演模型，通过铅场矩阵将磁场与子宫表面的源电流联系起来。为了计算铅场矩阵，我们使用了一种考虑了子宫肌层各向异性的有限元方法。我们通过最小化一个约束最小二乘问题来估计源电流，以解决反问题的非唯一性问题。由于我们缺乏来源电流的真实情况，我们建议使用基于绝对值的方法根据我们估计的来源电流预测宫内压力，并将结果与收缩活动中记录的实际腹部偏转进行比较。我们通过显示子宫肌层中不同位置的铅场来测试铅场矩阵的可行性，这些铅场是由假定的源电流在子宫肌层的不同位置产生的：宫颈和眼底，左和右，前面和后面。然后，我们通过使用三个合成的MMG数据集来说明我们的方法，这些数据集是使用我们之前开发的子宫收缩的多尺度模型生成的，以及三个真实的MMG数据集，其中一个数据集同时进行了真实的腹部偏转测量。数值结果表明，我们的方法能够捕捉到怀孕期间人类子宫的局部收缩活动。此外，关于子宫收缩的时间，预测的宫内压力与实际的腹部偏转是相当一致的。
Understanding the uterine source of the electrophysiological activity of contractions during pregnancy is of scientific interest and potential clinical applications. In this work, we propose a method to estimate uterine source currents from magnetomyography (MMG) temporal course measurements on the abdominal surface. In particular, we develop a linear forward model, based on the quasistatic Maxwell’s equations and a realistic four-compartment volume conductor, relating the magnetic fields to the source currents on the uterine surface through a lead-field matrix. To compute the lead-field matrix, we use a finite element method that considers the anisotropic property of the myometrium. We estimate the source currents by minimizing a constrained least-squares problem to solve the non-uniqueness issue of the inverse problem. Because we lack the ground truth of the source current, we propose to predict the intrauterine pressure from our estimated source currents by using an absolute-value-based method and compare the result with real abdominal deflection recorded during contractile activity. We test the feasibility of the lead-field matrix by displaying the lead fields that are generated by putative source currents at different locations in the myometrium: cervix and fundus, left and right, front and back. We then illustrate our method by using three synthetic MMG data sets, which are generated using our previously developed multiscale model of uterine contractions, and three real MMG data sets, one of which has simultaneous real abdominal deflection measurements. The numerical results demonstrate the ability of our method to capture the local contractile activity of human uterus during pregnancy. Moreover, the predicted intrauterine pressure is in fair agreement with the real abdominal deflection with respect to the timing of uterine contractions.
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DOI：
10.1016/0013-4694(92)90172-e
发表时间：
1992-03-01
期刊：
ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY
影响因子：
--
作者：
AHLFORS, SP;ILMONIEMI, RJ;HAMALAINEN, MS
通讯作者：
HAMALAINEN, MS
影响因子：
3.6
作者：
Fuchs, A. R.
通讯作者：
Fuchs, A. R.
影响因子：
2.9
作者：
Barclay, Mel;Andersen, H.;Simon, Carl
通讯作者：
Simon, Carl
影响因子：
44.1
作者：
HAMALAINEN, M;HARI, R;LOUNASMAA, OV
通讯作者：
LOUNASMAA, OV
影响因子：
3.2
作者：
PLONSEY, R
通讯作者：
PLONSEY, R