title: Removing ballistocardiogram (BCG) artifact from full-scalp EEG acquired inside the MR scanner with Orthogonal Matching Pursuit (OMP).
abstract: Ballistocardiogram (BCG) artifact remains a major challenge that renders electroencephalographic (EEG) signals hard to interpret in simultaneous EEG and functional MRI (fMRI) data acquisition. Here, we propose an integrated learning and inference approach that takes advantage of a commercial high-density EEG cap, to estimate the BCG contribution in noisy EEG recordings from inside the MR scanner. To estimate reliably the full-scalp BCG artifacts, a near-optimal subset (20 out of 256) of channels first was identified using a modified recording setup. In subsequent recordings inside the MR scanner, BCG-only signal from this subset of channels was used to generate continuous estimates of the full-scalp BCG artifacts via inference, from which the intended EEG signal was recovered. The reconstruction of the EEG was performed with both a direct subtraction and an optimization scheme. We evaluated the performance on both synthetic and real contaminated recordings, and compared it to the benchmark Optimal Basis Set (OBS) method. In the challenging non-event-related-potential (non-ERP) EEG studies, our reconstruction can yield more than fourteen-fold improvement in reducing the normalized RMS error of EEG signals, compared to OBS.
authors.affiliation: Department of Bioengineering, University of California Los Angeles, CA, USA.
authors.forename: Hongjing
authors.initials: H
authors.lastname: Xia
authors.affiliation: Department of Bioengineering, University of California Los Angeles, CA, USA ; Department of Radiation Oncology, University of California Los Angeles, CA, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Ruan
authors.affiliation: Department of Bioengineering, University of California Los Angeles, CA, USA ; Department of Psychiatry, Neurology, Radiology, Psychology, Biomedical Physics, California NanosSystems Institute, University of California Los Angeles, CA, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Cohen
keywords: alpha waves; artifact removal; ballistocardiogram; brain rhythms; orthogonal matching pursuit (OMP); signal separation; simultaneous EEG-fMRI; subset selection