Sekihara K, Scholz B
Central Research Laboratory, Hitachi, Limited, Tokyo, Japan.
IEEE Trans Biomed Eng. 1995 Feb;42(2):149-57. doi: 10.1109/10.341827.
This paper proposes two methods for reconstructing current distributions from biomagnetic measurements. Both of these methods are based on estimating the source-current covariance matrix from the measured-data covariance matrix. One method is the reconstruction of average current intensity distributions. This method first estimates the source-current covariance matrix and, using its diagonal terms, it reconstructs current intensity distributions averaged over a certain time. Although the method does not reconstruct the orientation of each current element at each time instant, it can retrieve information regarding the current time-averaged intensity at each voxel location using extremely low SNR data. The second method is Wiener reconstruction using the estimated source-current covariance matrix. Unlike the first method, this Wiener reconstruction can provide a current distribution with its orientation at each time instant. Computer simulation shows that the Wiener method is less affected by the choice of the regularization parameter, resulting in a method that is more effective than the conventional minimum-norm method when the SNR of the measurement is low.
本文提出了两种从生物磁测量中重建电流分布的方法。这两种方法均基于从测量数据协方差矩阵估计源电流协方差矩阵。一种方法是重建平均电流强度分布。该方法首先估计源电流协方差矩阵，并利用其对角项重建在特定时间内平均的电流强度分布。尽管该方法不能重建每个电流元在每个时刻的方向，但它可以使用极低信噪比的数据检索每个体素位置处关于电流时间平均强度的信息。第二种方法是使用估计的源电流协方差矩阵进行维纳重建。与第一种方法不同，这种维纳重建可以在每个时刻提供具有方向的电流分布。计算机模拟表明，维纳方法受正则化参数选择的影响较小，当测量的信噪比很低时，该方法比传统的最小范数方法更有效。
