Hu Yegang, Yin Chunli, Zhang Jicong, Wang Yuping
School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
Beijing Advanced Innovation Centre for Big Data-Based Precision Medicine, Beihang University, Beijing, China.
Front Neurosci. 2018 Sep 5;12:616. doi: 10.3389/fnins.2018.00616. eCollection 2018.
Beamforming techniques have played a prominent role in source imaging in neuroimaging and in locating epileptogenic zones. However, existing vector-beamformers are sensitive to noise on localization of epileptogenic zones. In this study, partial least square (PLS) was used to aid the minimum variance beamforming approach for source imaging with magnetoencephalography (MEG) arrays, and verified its effectiveness in simulated data and epilepsy data. First, PLS was employed to extract the components of the MEG arrays by maximizing the covariance between a linear combination of the predictors and the class variable. Noise was then removed by reconstructing the MEG arrays based on those components. The minimum variance beamforming method was used to estimate a source model. Simulations with a realistic head model and varying noise levels indicated that the proposed approach can provide higher spatial accuracy than other well-known beamforming methods. For real MEG recordings in 10 patients with temporal lobe epilepsy, the ratios of the number of spikes localized in the surgical excised region to the total number of spikes using the proposed method were higher than that of the dipole fitting method. These localization results using the proposed method are more consistent with the clinical evaluation. The proposed method may provide a new imaging marker for localization of epileptogenic zones.
波束形成技术在神经成像的源成像以及癫痫源区定位中发挥了重要作用。然而，现有的矢量波束形成器在癫痫源区定位时对噪声敏感。在本研究中，偏最小二乘法（PLS）被用于辅助基于脑磁图（MEG）阵列的最小方差波束形成源成像方法，并在模拟数据和癫痫数据中验证了其有效性。首先，通过最大化预测变量的线性组合与类别变量之间的协方差，使用PLS提取MEG阵列的成分。然后基于这些成分重建MEG阵列以去除噪声。使用最小方差波束形成方法估计源模型。使用逼真的头部模型和不同噪声水平的模拟表明，所提出的方法比其他知名的波束形成方法能提供更高的空间精度。对于10例颞叶癫痫患者的真实MEG记录，使用所提出方法定位在手术切除区域的尖峰数量与尖峰总数的比率高于偶极子拟合方法。使用所提出方法的这些定位结果与临床评估更一致。所提出的方法可能为癫痫源区定位提供一种新的成像标志物。
