Stepping stone sampling for retrieving artifact-free electroencephalogram during functional magnetic resonance imaging
Stepping stone sampling for retrieving artifact-free electroencephalogram during functional magnetic resonance imaging
复制标题
DOI：
10.1016/s1053-8119(03)00048-x
复制
发表时间：
2003-06-01
期刊：
影响因子：
5.7
通讯作者：
Saitoh, O
中科院分区：
文献类型：
--
作者：
Anami, K;Mori, T;Saitoh, O
心冲击图和成像伪影对同步脑电图（EEG）和功能性磁共振成像（fMRI）记录造成严重干扰。特别是，成像伪影的大幅度排除了在fMRI扫描期间容易检索EEG信号。以20，000 Hz数字化速率与3000 Hz低通滤波器相结合的记录揭示了成像伪影的真实的波形，其中阐明了每个伪影峰值精确地对应于每个梯度分量，并且实际上具有原始梯度脉冲的差分波形。基于这一发现，为了在fMRI采集过程中检索EEG信号，修改了一个脉冲型回波平面序列，以便在伪影位于基线水平附近的时间段内，仅以每1000 As（数字化速率1000 Hz）进行EEG采样。这种方法被称为“垫脚石采样”，大大削弱了成像伪影的幅度。从平均伪影波形中减去伪影的残余部分。在人类研究中，通过检查成功检索活动，并在眼睛睁开/闭合期间观察到其衰减/增强。快速傅立叶变换分析进一步揭示，即使从DC到120 Hz，在扫描期间检索的EEG数据与在没有扫描期间检索的数据具有非常相似的功率分布，这意味着检索的EEG信号的高频带的可用性，甚至包括伽马带。(C)2003 Elsevier Science（美国）。All rights reserved.
Ballistocardiogram and imaging artifacts cause major interference with simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) recording. In particular, the large amplitude of the imaging artifact precludes easy retrieval of EEG signals during fMRI scanning. Recording with 20,000-Hz digitization rate combined with 3000-Hz low-pass filter revealed the real waveform of the imaging artifact, in which it was elucidated that each artifact peak precisely corresponded to each gradient component and actually had differential waveforms of the original gradient pulses. Based on this finding, to retrieve EEG signal during fMRI acquisition, a blip-type echo planar sequence was modified so that EEG sampling might be performed at every 1000 As (digitization rate 1000 Hz) exclusively in the period in which the artifact resided around the baseline level. This method, called "stepping stone sampling," substantially attenuated the amplitude of the imaging artifact. The remnant of the artifact was subtracted from the averaged artifact waveform. In human studies, a activity was successfully retrieved by inspection, and its attenuation/augmentation was observed during eyes open/closed periods. Fast Fourier transform analysis further revealed that even from DC up to 120 Hz, retrieved EEG data during scanning had very similar power distributions to the data retrieved during no scanning, implying the availability of the high-frequency band of the retrieved EEG signals, including even the gamma band. (C) 2003 Elsevier Science (USA). All rights reserved.