title: Gradient induced artifacts in simultaneous EEG-fMRI: Effect of synchronization on spiral and EPI k-space trajectories.
abstract: The nature of the gradient induced electroencephalography (EEG) artifact is analyzed and compared for two functional magnetic resonance imaging (fMRI) pulse sequences with different k-space trajectories: echo planar imaging (EPI) and spiral. Furthermore, the performance of the average artifact subtraction algorithm (AAS) to remove the gradient artifact for both sequences is evaluated. The results show that the EEG gradient artifact for spiral sequences is one order of magnitude higher than for EPI sequences due to the chirping spectrum of the spiral sequence and the dB/dt of its crusher gradients. However, in the presence of accurate synchronization, the use of AAS yields the same artifact suppression efficiency for both pulse sequences below 80Hz. The quality of EEG signal after AAS is demonstrated for phantom and human data. EEG spectrogram and visual evoked potential (VEP) are compared outside the scanner and use both EPI and spiral pulse sequences. MR related artifact residues affect the spectra over 40Hz (less than 0.2 μV up to 120Hz) and modify the amplitude of P1, N2 and P300 in the VEP. These modifications in the EEG signal have to be taken into account when interpreting EEG data acquired in simultaneous EEG-fMRI experiments.
authors.affiliation: Neuroimaging Lab., Center for Biomedical Technology, Universidad Politécnica de Madrid and Universidad Rey Juan Carlos, Autopista M40, Km. 38, 28223, Pozuelo de Alarcón, Spain. Electronic address: anabea.solana@ctb.upm.es.
authors.forename: A B
authors.initials: AB
authors.lastname: Solana
authors.affiliation: Neuroimaging Lab., Center for Biomedical Technology, Universidad Politécnica de Madrid and Universidad Rey Juan Carlos, Autopista M40, Km. 38, 28223, Pozuelo de Alarcón, Spain; Medical Image Analysis Lab. Fundación Reina Sofía- Fundación CIEN, C/Valderrebollo 5, 28031, Madrid, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Hernández-Tamames
authors.affiliation: Neuroimaging Lab., Center for Biomedical Technology, Universidad Politécnica de Madrid and Universidad Rey Juan Carlos, Autopista M40, Km. 38, 28223, Pozuelo de Alarcón, Spain; Medical Image Analysis Lab. Fundación Reina Sofía- Fundación CIEN, C/Valderrebollo 5, 28031, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Manzanedo
authors.affiliation: Research and Collaborations, General Electric Healthcare, 551 Rue Minière, 78530, Buc, France.
authors.forename: R
authors.initials: R
authors.lastname: García-Álvarez
authors.affiliation: Department of Neuroimaging, Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF, United Kingdom.
authors.forename: F O
authors.initials: FO
authors.lastname: Zelaya
authors.affiliation: Neuroimaging Lab., Center for Biomedical Technology, Universidad Politécnica de Madrid and Universidad Rey Juan Carlos, Autopista M40, Km. 38, 28223, Pozuelo de Alarcón, Spain.
authors.forename: F
authors.initials: F
authors.lastname: del Pozo
mesh_terms: D016477:Artifacts; D001921:Brain / Q000502:physiology*; D017352:Echo-Planar Imaging; D004569:Electroencephalography; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation; D008279:Magnetic Resonance Imaging; D019047:Phantoms, Imaging
keywords: EPI fMRI; Gradient artifact; Simultaneous EEG-fMRI; Spiral fMRI; Synchronization