title: Muscle and eye movement artifact removal prior to EEG source localization.
abstract: 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.
authors.affiliation: Medical Imaging and Signal Processing Group, Department of Electronics & Information Systems, Ghent University, Sint-Pieternieuwstraat 41, Ghent, Belgium. hans.hallez@ugent.be
authors.forename: Hans
authors.initials: H
authors.lastname: Hallez
authors.forename: Anneleen
authors.initials: A
authors.lastname: Vergult
authors.forename: Ronald
authors.initials: R
authors.lastname: Phlypo
authors.forename: Peter
authors.initials: P
authors.lastname: Van Hese
authors.forename: Wim
authors.initials: W
authors.lastname: De Clercq
authors.forename: Yves
authors.initials: Y
authors.lastname: D'Asseler
authors.forename: Rik
authors.initials: R
authors.lastname: Van de Walle
authors.forename: Bart
authors.initials: B
authors.lastname: Vanrumste
authors.forename: Wim
authors.initials: W
authors.lastname: Van Paesschen
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Huffel
authors.forename: Ignace
authors.initials: I
authors.lastname: Lemahieu
mesh_terms: 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