Muscle and eye movement artifact removal prior to EEG source localization.
Muscle and eye movement artifacts are very prominent in the ictal EEG of patients suffering from epilepsy, thus making the dipole localization of ictal activity very unreliable. Recently, two techniques (BSS-CCA and pSVD) were developed to remove those artifacts. The purpose of this study is to assess whether the removal of muscle and eye movement artifacts improves the EEG dipole source localization. We used a total of 8 EEG fragments, each from another patient, first unfiltered, then filtered by the BSS-CCA and pSVD. In both the filtered and unfiltered EEG fragments we estimated multiple dipoles using RAP-MUSIC. The resulting dipoles were subjected to a K-means clustering algorithm, to extract the most prominent cluster. We found that the removal of muscle and eye artifact results to tighter and more clear dipole clusters. Furthermore, we found that localization of the filtered EEG corresponded with the localization derived from the ictal SPECT in 7 of the 8 patients. Therefore, we can conclude that the BSS-CCA and pSVD improve localization of ictal activity, thus making the localization more reliable for the presurgical evaluation of the patient.
Hallez
Hans
H
Medical Imaging and Signal Processing Group, Department of Electronics & Information Systems, Ghent University, Sint-Pieternieuwstraat 41, Ghent, Belgium. hans.hallez@ugent.be
Vergult
Anneleen
A
Phlypo
Ronald
R
Van Hese
Peter
P
De Clercq
Wim
W
D'Asseler
Yves
Y
Van de Walle
Rik
R
Vanrumste
Bart
B
Van Paesschen
Wim
W
Van Huffel
Sabine
S
Lemahieu
Ignace
I
D000465:Algorithms; D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology*; D005133:Eye Movements; D006801:Humans; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity