COMPARISON OF BEM WITH 3-SPHERICAL SHELL MODEL USING ACTUAL SKULL CONDUCTIVITIES
Abstract number :
1.098
Submission category :
Year :
2002
Submission ID :
3470
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Massoud Akhtari, Howard C. Bryant, Adam N. Mamelak, Waren Merifield, William W. Sutherling. MEG Laboratory, Huntington Medical Research Institute, Pasadena, CA; Physics and Astronomy, The University of New Mexico, Albuquerque, NM; Nerosurgery, Epilepcy an
RATIONALE: Misspecification of skull conductivity and head geometry may lead to inaccurate source localization.
METHODS: Bulk conductivities of three live human skulls were measured using the four-electrode method in three patients undergoing neurosurgery. These values were 0.0112, 0.0093, and 0.0085 S/m. Somatosensory evoked electroencephalogram (EEG) data were obtained by stimulating the right median nerve of a normal subject. EEG source localizations were performed on these data using single equivalent moving current dipole model in a 3-shell sphere and boundary element method (BEM) (CURRY[reg]) while varying the skull conductivity between the three measured values and the results were compared to those obtained from the standard value of 0.0042 S/m.
RESULTS: The maximum variation of the absolute source location using the realistic skull conductivity values compared to the standard value was 6.6 mm using BEM and 12.7 mm using the 3-shell sphere model.
CONCLUSIONS: Applying actual skull conductivities along with realistic geometrical head models will lead to less variation in EEG source localization compared with the 3-spherical shell model.
[Supported by: NIH Grant NS20806]