title: Methods for pulse artefact reduction: experiences with EEG data recorded at 9.4 T static magnetic field.
abstract: BACKGROUND
  The feasibility of recording electroencephalography (EEG) at ultra-high static magnetic fields up to 9.4 T was recently demonstrated and is expected to be incorporated into functional magnetic resonance imaging (fMRI) studies at 9.4 T. Correction of the pulse artefact (PA) is a significant challenge since its amplitude is proportional to the strength of the magnetic field in which EEG is recorded.
  
  
  METHODS
  We conducted a study in which different PA correction methods were applied to EEG data recorded inside a 9.4 T scanner in order to retrieve visual P100 and auditory P300 evoked potentials. We explored different PA reduction methods, including the optimal basis set (OBS) method as well as objective and subjective component rejection using independent component analysis (ICA).
  
  
  RESULTS
  ICA followed by objective rejection of components is optimal for retrieving visual P100 and auditory P300 from EEG data recorded inside the scanner.
  
  
  METHODS
  Previous studies suggest that OBS or OBS followed by ICA are optimal for retrieving evoked potentials at 3T. In our EEG data recorded at 9.4 T OBS performed alone was not fully optimal for the identification of evoked potentials. OBS followed by ICA was partially effective.
  
  
  CONCLUSIONS
  In this study ICA has been shown to be an important tool for correcting the PA in EEG data recorded at 9.4 T, particularly when automated rejection of components is performed.
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany. Electronic address: j.arrubla@fz-juelich.de.
authors.forename: Jorge
authors.initials: J
authors.lastname: Arrubla
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany; Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Germany; JARA - BRAIN - Translational Medicine, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Neuner
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Dammers
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany; Department of Neurology, RWTH Aachen University, Germany.
authors.forename: Lukas
authors.initials: L
authors.lastname: Breuer
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany.
authors.forename: Tracy
authors.initials: T
authors.lastname: Warbrick
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Hahn
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Poole
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Boers
authors.affiliation: Institute of Neuroscience and Medicine 4, INM 4, Forschungszentrum Jülich, Germany; JARA - BRAIN - Translational Medicine, Germany; Department of Neurology, RWTH Aachen University, Germany.
authors.forename: N Jon
authors.initials: NJ
authors.lastname: Shah
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000098:blood supply / Q000502:physiology* / Q000528:radiation effects*; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology / Q000528:radiation effects*; D005074:Evoked Potentials, Visual / Q000502:physiology* / Q000528:radiation effects*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Auditory evoked potentials; EEG; Independent component analysis; MR; Optimal basis set; Pulse artefact; Ultra-high field; Visual evoked potentials