Removal of time-varying gradient artifacts from EEG data acquired during continuous fMRI

Autor: Robert Todd Constable, Mark Abildgaard, Terry Nixon, Michiro Negishi
Rok vydání: 2004
Předmět:
Zdroj: Clinical Neurophysiology. 115:2181-2192
ISSN: 1388-2457
DOI: 10.1016/j.clinph.2004.04.005
Popis: Objective: Recording low amplitude electroencephalography (EEG) signals in the face of large gradient artifacts generated by changing functional magnetic resonance imaging (fMRI) magnetic fields continues to be a challenge. We present a new method of removing gradient artifacts with time-varying waveforms, and evaluate it in continuous (non-interleaved) simultaneous EEG‐ fMRI experiments. Methods: The current method consists of an analog filter, an EEG‐fMRI timing error correction algorithm, and a temporal principal component analysis based gradient noise removal algorithm. We conducted a phantom experiment and a visual oddball experiment to evaluate the method. Results: The results from the phantom experiment showed that the current method reduced the number of averaged samples required to obtain high correlation between injected and recovered signals, compared to a conventional average waveform subtraction method with adaptive noise canceling. For the oddball experiment, the results obtained from the two methods were very similar, except that the current method resulted in a higher P300 amplitude when the number of averaged trials was small. Conclusions: The current method enabled us to obtain high quality EEGs in continuous simultaneous EEG ‐ fMRI experiments. Significance: Continuous simultaneous EEG ‐ fMRI acquisition enables efficient use of data acquisition time and better monitoring of rare EEG events. q 2004 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
Databáze: OpenAIRE
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