title: Influence of skull conductivity perturbations on EEG dipole source analysis.
abstract: OBJECTIVE
  Electroencephalogram (EEG) source analysis is a noninvasive technique used in the presurgical of epilepsy. In this study, the dipole location and orientation errors due to skull conductivity perturbations were investigated in two groups of three-dimensional head models: A spherical head model and a realistic head model.
  
  
  METHODS
  In each group, the head model had a brain-to-skull conductivity ratio (Rsigma) within the range of 10-40. Solving the forward problem in the head model with skull conductivity perturbations along with the inverse problem in the baseline head model with Rsigma=20 permitted the derivation of the dipole estimation errors.
  
  
  RESULTS
  Perturbations in the skull conductivity generated dipole location and orientation errors: The larger the perturbations, the larger the errors and the error ranges. The dipole orientation error due to skull conductivity perturbations was not great (maximal mean of < 5 degrees) in this study, but the dipole location error was notable (maximal mean of > 5 mm).
  
  
  CONCLUSIONS
  Therefore, the influence of skull conductivity perturbations on EEG dipole source analysis cannot be neglected. This study suggests that it is necessary to measure the skull conductivity of the individual patients in order to achieve accurate EEG source analysis.
authors.affiliation: Faculty of Engineering, Ghent University-IBBT, Belgium.
authors.forename: Fangmin
authors.initials: F
authors.lastname: Chen
authors.forename: Hans
authors.initials: H
authors.lastname: Hallez
authors.forename: Steven
authors.initials: S
authors.lastname: Staelens
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D003198:Computer Simulation; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004553:Electric Conductivity; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D008959:Models, Neurological; D012886:Skull / Q000502:physiology*