DocumentCode :
762105
Title :
In vivo measurement of the brain and skull resistivities using an EIT-based method and the combined analysis of SEF/SEP data
Author :
Goncalve, S. ; de Munck, J.C. ; Verbunt, J.P.A. ; Heethaar, R.M. ; Silva, F. H Lopes da
Author_Institution :
MEG Centre, Vrije Univ. Med. Centre, Amsterdam, Netherlands
Volume :
50
Issue :
9
fYear :
2003
Firstpage :
1124
Lastpage :
1127
Abstract :
Results of "in vivo" measurements of the skull and brain resistivities are presented for six subjects. Results are obtained using two different methods, based on spherical head models. The first method uses the principles of electrical impedance tomography (EIT) to estimate the equivalent electrical resistivities of brain (ρbrain), skull (ρskull) and skin (ρskin) according to S. Goncalves et al., Physiol. Meas., vol. 21, p. 379-93 (2000).. The second one estimates the same parameters through a combined analysis of the evoked somatosensory cortical response, recorded simultaneously using magnetoencephalography (MEG) and electroencephalography (EEG). The EIT results, obtained with the same relative skull thickness (0.05) for all subjects, show a wide variation of the ratio ρskullbrain among subjects (average =72, SD=48%). However, the ρskullbrain ratios of the individual subjects are well reproduced by combined analysis of somatosensory evoked fields (SEF) and somatosensory evoked potentials (SEP). These preliminary results suggest that the ρskullbrain variations over subjects cannot be disregarded in the EEG inverse problem (IP) when a spherical model is used. The agreement between EIT and SEF/SEP points to the fact that whatever the source of variability, the proposed EIT-based method skull/ρbrain, ρbrain, ρskull and ρskin.
Keywords :
brain models; electric impedance imaging; electric resistance measurement; electroencephalography; inverse problems; medical signal processing; somatosensory phenomena; EEG; EEG inverse problem; MEG; brain resistivity measurement; electric impedance tomography; electrodiagnostics; evoked somatosensory cortical response; relative skull thickness; skull resistivity measurement; somatosensory evoked fields; somatosensory evoked potentials; Conductivity; Electric resistance; Electroencephalography; Impedance; In vivo; Magnetic heads; Parameter estimation; Skin; Skull; Tomography; Brain; Brain Mapping; Electric Impedance; Electroencephalography; Evoked Potentials, Somatosensory; Head; Models, Biological; Reproducibility of Results; Sensitivity and Specificity; Skin Physiology; Skull; Tomography;
fLanguage :
English
Journal_Title :
Biomedical Engineering, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9294
Type :
jour
DOI :
10.1109/TBME.2003.816072
Filename :
1220220
Link To Document :
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