title: ICA decomposition of EEG signal for fMRI processing in epilepsy.
abstract: In this study, we introduce a new approach to process simultaneous Electroencephalography and functional Magnetic Resonance Imaging (EEG-fMRI) data in epilepsy. The method is based on the decomposition of the EEG signal using independent component analysis (ICA) and the usage of the relevant components' time courses to define the event related model necessary to find the regions exhibiting fMRI signal changes related to interictal activity. This approach achieves a natural data-driven differentiation of the role of distinct types of interictal activity with different amplitudes and durations in the epileptogenic process. Agreement between the conventional method and this new approach was obtained in 6 out of 9 patients that had interictal activity inside the scanner. In all cases, the maximum Z-score was greater in the fMRI studies based on ICA component method and the extent of activation was increased in 5 out of the 6 cases in which overlap was found. Furthermore, the three cases where an agreement was not found were those in which no significant activation was found at all using the conventional approach.
authors.affiliation: Visual Neuroscience Lab, IBILI, University of Coimbra, Portugal. jose.marques@epfl.ch
authors.forename: José P
authors.initials: JP
authors.lastname: Marques
authors.forename: José
authors.initials: J
authors.lastname: Rebola
authors.forename: Patrícia
authors.initials: P
authors.lastname: Figueiredo
authors.forename: Alda
authors.initials: A
authors.lastname: Pinto
authors.forename: Francisco
authors.initials: F
authors.lastname: Sales
authors.forename: Miguel
authors.initials: M
authors.lastname: Castelo-Branco
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000465:Algorithms; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted