Carbon-wire loop based artifact correction outperforms post-processing EEG/fMRI corrections--A validation of a real-time simultaneous EEG/fMRI correction method.
Simultaneous EEG-fMRI combines two powerful neuroimaging techniques, but the EEG signal suffers from severe artifacts in the MRI environment that are difficult to remove. These are the MR scanning artifact and the blood-pulsation artifact--strategies to remove them are a topic of ongoing research. Additionally large, unsystematic artifacts are produced across the full frequency spectrum by the magnet's helium pump (and ventilator) systems which are notoriously hard to remove. As a consequence, experimenters routinely deactivate the helium pump during simultaneous EEG-fMRI acquisitions which potentially risks damaging the MRI system and necessitates more frequent and expensive helium refills. We present a novel correction method addressing both helium pump and ballisto-cardiac (BCG) artifacts, consisting of carbon-wire loops (CWL) as additional sensors to accurately track unpredictable artifacts related to subtle movements in the scanner, and an EEGLAB plugin to perform artifact correction. We compare signal-to-noise metrics of EEG data, corrected with CWL and three conventional correction methods, for helium pump off and on measurements. Because the CWL setup records signals in real-time, it fits requirements of applications where immediate correction is necessary, such as neuro-feedback applications or stimulation time-locked to specific sleep oscillations. The comparison metrics in this paper relate to: (1) the EEG signal itself, (2) the "eyes open vs. eyes closed" effect, and (3) an assessment of how the artifact corrections impacts the ability to perform meaningful correlations between EEG alpha power and the BOLD signal. Results show that the CWL correction corrects for He pump artifact and also produces EEG data more comparable to EEG obtained outside the magnet than conventional post-processing methods.
Clinical Affective Neuroimaging Laboratory, Otto-von-Guericke University, Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany; Department of Medical Psychology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University and Medical Center, Amsterdam, The Netherlands. Electronic address: johan.vandermeer@med.ovgu.de.
Johan N
JN
van der Meer
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
André
A
Pampel
Department of Sleep and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Academy of Arts and Sciences, Amsterdam, Netherlands; Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University and Medical Center, Amsterdam, The Netherlands.
Eus J W
EJW
Van Someren
Department of Sleep and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Academy of Arts and Sciences, Amsterdam, Netherlands.
Jennifer R
JR
Ramautar
Department of Cognition and Emotion, Netherlands Institute for Neuroscience, An Institute of the Royal Academy of Arts and Sciences, Amsterdam, Netherlands; Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University and Medical Center, Amsterdam, The Netherlands; Department of Medical Psychology, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, VU University and Medical Center, Amsterdam, The Netherlands.
Ysbrand D
YD
van der Werf
Department of Sleep and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Academy of Arts and Sciences, Amsterdam, Netherlands.
German
G
Gomez-Herrero
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Jöran
J
Lepsien
Department of Psychiatry and Neuroimaging Center, Technische Universität Dresden, Dresden, Germany.
Lydia
L
Hellrung
Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany.
Hermann
H
Hinrichs
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Harald E
HE
Möller
Clinical Affective Neuroimaging Laboratory, Otto-von-Guericke University, Magdeburg, Germany; Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Psychiatry, Otto-von-Guericke University, Magdeburg, Germany. Electronic address: martin.walter@med.ovgu.de.
Martin
M
Walter
D000328:Adult; D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult