title: Comparison of BCG artifact removal methods for evoked responses in simultaneous EEG-fMRI.
abstract: Simultaneous recording of electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) has gained attention due to the complimentary properties of the two imaging modalities. Their combined recording enables the study of brain function while taking advantage of the high temporal resolution of EEG and high spatial resolution of fMRI. However EEG data recorded inside the MR scanner is significantly contaminated by two main sources of artifacts: MR gradient artifacts and ballistocardiogram (BCG) artifacts. Most existing removal approaches for these artifacts fall into two main categories: average artifact subtraction (AAS) and optimal basis selection (OBS). While these techniques can improve the data quality significantly, highly effective removal of artifacts - particularly the BCG artifact - from the data is still lacking. Here, we compared two of the most commonly used algorithms for BCG artifact removal (OBS and AAS) based on the estimated signal-to-noise ratio (SNR) of auditory and visual evoked responses recorded during fMRI acquisition. We also further compared optimization of OBS for groups, and at the individual subject and run level. The results suggest that performance of the OBS algorithm can be significantly improved by choosing the optimum number of principal components. Furthermore, optimizing the number of principal components at the individual participant and run level results in significant improvements in the SNR of evoked responses compared to group optimization.
authors.affiliation: Rotman Research Institute, Baycrest Hospital, Toronto, ON, Canada M6A 2E1; Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada. Electronic address: nshams@research.baycrest.org.
authors.forename: Nasim
authors.initials: N
authors.lastname: Shams
authors.affiliation: Rotman Research Institute, Baycrest Hospital, Toronto, ON, Canada M6A 2E1; Department of Psychology, University of Toronto, Toronto, ON, Canada.
authors.forename: Claude
authors.initials: C
authors.lastname: Alain
authors.affiliation: Rotman Research Institute, Baycrest Hospital, Toronto, ON, Canada M6A 2E1; Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Strother
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D016477:Artifacts; D001450:Ballistocardiography / Q000009:adverse effects*; D001921:Brain / Q000098:blood supply* / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D059629:Signal-To-Noise Ratio; D013057:Spectrum Analysis; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Artifact removal; BCG artifact; Optimization; Sensory evoked potentials; Signal-to-noise ratio; Simultaneous EEG–fMRI