| Effects of simultaneous EEG recording on MRI data quality at 1.5, 3 and 7 tesla. | |
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MedLine Citation:
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PMID: 17689767 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Although the focus of attention on data degradation during simultaneous MRI/EEG recording has to date largely been upon EEG artefacts, the presence of the conducting wires and electrodes of the EEG recording system also causes some degradation of MRI data quality. This may result from magnetic susceptibility effects which lead to signal drop-out and image distortion, as well as the perturbation of the radiofrequency fields, which can cause local signal changes and a global reduction in the signal to noise ratio (SNR) of magnetic resonance images. Here, we quantify the effect of commercially available 32 and 64 electrode caps on the quality of MR images obtained in scanners operating at magnetic fields of 1.5, 3 and 7 T, via the use of MR-based, field-mapping techniques and analysis of the SNR in echo planar image time series. The electrodes are shown to be the dominant source of magnetic field inhomogeneity, although the localised nature of the field perturbation that they produce means that the effect on the signal intensity from the brain is not significant. In the particular EEG caps investigated here, RF inhomogeneity linked to the longer ECG and EOG leads causes some reduction in the signal intensity in images obtained at 3 and 7 T. Measurements of the standard deviation of white matter signal in EPI time series indicates that the introduction of the EEG cap produces a small reduction in the image signal to noise ratio, which increases with the number of electrodes used. |
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Authors:
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Karen Mullinger; Stefan Debener; Ronald Coxon; Richard Bowtell |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't Date: 2007-08-09 |
Journal Detail:
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Title: International journal of psychophysiology : official journal of the International Organization of Psychophysiology Volume: 67 ISSN: 0167-8760 ISO Abbreviation: Int J Psychophysiol Publication Date: 2008 Mar |
Date Detail:
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Created Date: 2008-02-25 Completed Date: 2008-05-02 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8406214 Medline TA: Int J Psychophysiol Country: Netherlands |
Other Details:
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Languages: eng Pagination: 178-88 Citation Subset: IM |
Affiliation:
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Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Artifacts* Brain Mapping / instrumentation* Cerebral Cortex / physiology Electroencephalography / instrumentation* Electromagnetic Fields Humans Magnetic Resonance Imaging / instrumentation* Phantoms, Imaging Reference Values Signal Processing, Computer-Assisted* |
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