Paper Info
Title
Concordance between distributed EEG source localization and simultaneous EEG-fMRI studies of epileptic spikes
Abstract
In order to analyze where epileptic spikes are generated, we assessed the level of concordance between EEG source localization using distributed source models and simultaneous EEG-fMRI which measures the hemodynamic correlates of EEG activity. Data to be compared were first estimated on the same cortical surface and two comparison strategies were used: (1) MEM-concordance: a comparison between EEG sources localized with the Maximum Entropy on the Mean (MEM) method and fMRI clusters showing a significant hemodynamic response. Minimal geodesic distances between local extrema and overlap measurements between spatial extents of EEG sources and fMRI clusters were used to quantify MEM-concordance. (2) fMRI-relevance: estimation of the fMRI-relevance index α quantifying if sources located in an fMRI cluster could explain some scalp EEG data, when this fMRI cluster was used to constrain the EEG inverse problem. Combining MEM-concordance and fMRI-relevance (α) indexes, each fMRI cluster showing a significant hemodynamic response (p<0.05 corrected) was classified according to its concordance with EEG data. Nine patients with focal epilepsy who underwent EEG-fMRI examination followed by EEG recording outside the scanner were selected for this study. Among the 62 fMRI clusters analyzed (7 patients), 15 (24%) found in 6 patients were highly concordant with EEG according to both MEM-concordance and fMRI-relevance. EEG concordance was found for 5 clusters (8%) according to α only, suggesting sources missed by the MEM. No concordance with EEG was found for 30 clusters (48%) and for 10 clusters (16%) α was significantly negative, suggesting EEG-fMRI discordance. We proposed two complementary strategies to assess and classify EEG-fMRI concordance. We showed that for most patients, part of the hemodynamic response to spikes was highly concordant with EEG sources, whereas other fMRI clusters in response to the same spikes were found distant or discordant with EEG sources.
Year
DOI
Venue
2008
10.1016/j.neuroimage.2007.08.020
NeuroImage
Keywords
Field
DocType
EEG source localization,Simultaneous EEG-fMRI,Concordance,Interictal epileptic spikes
Pattern recognition,Concordance,Brain activity and meditation,Source localization,Distributed source,Sound localization,Artificial intelligence,Principle of maximum entropy,EEG-fMRI,Electroencephalography,Mathematics
Journal
Volume
Issue
ISSN
39
2
1053-8119
Citations 
PageRank 
References 
13
0.79
14
Authors
7
Name
Order
Citations
PageRank
C. Grova1927.44
Jean Daunizeau2140671.53
Eliane Kobayashi31097.56
Andrew P Bagshaw419715.34
Jean-Marc Lina5130.79
François Dubeau6221.50
Jean Gotman724520.25