Artifact removal in co-registered EEG/fMRI by selective average subtraction
Artifact removal in co-registered EEG/fMRI by selective average subtraction
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DOI：
10.1016/j.clinph.2007.08.017
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发表时间：
2007-11-01
影响因子：
4.7
通讯作者：
de Munck, J. C.
中科院分区：
文献类型：
--
作者：
Goncalves, S. I.;Pouwels, P. J. W.;de Munck, J. C.
目的：脑电(EEG)和功能磁共振成像(FMRI)的联合配准仍然是一个挑战，因为磁共振序列磁场在EEG上产生了大的伪影。因此，我们提出了一种基于平均减法的算法，该算法能够校正脑电数据中的梯度伪影和脉搏伪影。方法：从脑电数据中估计MR序列的定时参数，并从数据中减去切片和体伪影模板。结果：该算法在保留自发脑电和视觉诱发电位的同时，只需对选择性平均数据进行减法，即可去除梯度和脉搏伪影。在频域中，伪影频率被强烈衰减。估计的MR序列时间参数表明，校正对切片时间值非常敏感。脉冲伪影聚类分析表明，脉冲伪影标记器的时间抖动是产生变异的主要原因。结论：选择性相减平均值结合适当的时间对准足以消除大部分MR伪影。意义：在同时进行EEG-fMRI扫描时，可以从被MR伪影破坏的原始信号中获得干净的EEG，而不需要使用专用硬件来同步EEG和fMRI时钟。(C)2007年国际临床神经生理学联合会。爱思唯尔爱尔兰有限公司出版。版权所有。
Objective: Co-registration of EEG (electroencephalogram) and fMRI (functional magnetic resonance imaging) remains a challenge due to the large artifacts induced on the EEG by the MR (magnetic resonance) sequence magnetic fields. Thus, we present an algorithm, based on the average-subtraction method, which is able to correct EEG data for gradient and pulse artifacts.Methods: MR sequence timing parameters are estimated from the EEG data and both slice and volume artifact templates are subtracted from the data. A clustering algorithm is proposed to account for the variability of the pulse artifact.Results: The algorithm is able to keep the spontaneous EEG as well as visual evoked potentials (VEPs), while removing gradient and pulse artifacts with only a subtraction of selectively averaged data. In the frequency domain, the artifact frequencies are strongly attenuated. Estimated MR sequence time parameters showed that the correction is extremely sensitive to the slice time value. Pulse artifact clustering showed that most of the variability is due to the time jitter of the pulse artifact markers.Conclusions: Selective subtraction of averages in combination with proper time alignment is enough to remove most of the MR-induced artifacts.Significance: Clean EEG can be obtained from raw signals that are corrupted by MR-induced artifacts during simultaneous EEG-fMRI scanning without using dedicated hardware to synchronize EEG and fMRI clocks. (c) 2007 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.