title: Using patient-specific hemodynamic response function in epileptic spike analysis of human epilepsy: a study based on EEG-fNIRS.
abstract: Functional near-infrared spectroscopy (fNIRS) can be combined with electroencephalography (EEG) to continuously monitor the hemodynamic signal evoked by epileptic events such as seizures or interictal epileptiform discharges (IEDs, aka spikes). As estimation methods assuming a canonical shape of the hemodynamic response function (HRF) might not be optimal, we sought to model patient-specific HRF (sHRF) with a simple deconvolution approach for IED-related analysis with EEG-fNIRS data. Furthermore, a quadratic term was added to the model to account for the nonlinearity in the response when IEDs are frequent. Prior to analyzing clinical data, simulations were carried out to show that the HRF was estimable by the proposed deconvolution methods under proper conditions. EEG-fNIRS data of five patients with refractory focal epilepsy were selected due to the presence of frequent clear IEDs and their unambiguous focus localization. For each patient, both the linear sHRF and the nonlinear sHRF were estimated at each channel. Variability of the estimated sHRFs was seen across brain regions and different patients. Compared with the SPM8 canonical HRF (cHRF), including these sHRFs in the general linear model (GLM) analysis led to hemoglobin activations with higher statistical scores as well as larger spatial extents on all five patients. In particular, for patients with frequent IEDs, nonlinear sHRFs were seen to provide higher sensitivity in activation detection than linear sHRFs. These observations support using sHRFs in the analysis of IEDs with EEG-fNIRS data.
authors.affiliation: Département de génie électrique, Institut de génie biomédical, École Polytechnique de Montréal, C.P.6079, Succ. Centre-ville, Montréal, QC H3C3A7, Canada.
authors.forename: Ke
authors.initials: K
authors.lastname: Peng
authors.affiliation: Service de neurologie, Hôpital Notre-Dame du CHUM, 1560 Rue Sherbrooke Est, Montréal, QC H3L4M1, Canada.
authors.forename: Dang Khoa
authors.initials: DK
authors.lastname: Nguyen
authors.affiliation: Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC H3T1C5, Canada.
authors.forename: Phetsamone
authors.initials: P
authors.lastname: Vannasing
authors.affiliation: Centre de recherche, Hôpital Sainte-Justine, 3175 Chemin de la côte-Sainte-Catherine, Montréal, QC H3T1C5, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Tremblay
authors.affiliation: Département de génie électrique, Institut de génie biomédical, École Polytechnique de Montréal, C.P.6079, Succ. Centre-ville, Montréal, QC H3C3A7, Canada; Institut de cardiologie de Montréal, Centre de recherche, 5000 Rue Bélanger Est, Montréal, QC H1T1C8, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lesage
authors.affiliation: Département de génie électrique, Institut de génie biomédical, École Polytechnique de Montréal, C.P.6079, Succ. Centre-ville, Montréal, QC H3C3A7, Canada; Institut de cardiologie de Montréal, Centre de recherche, 5000 Rue Bélanger Est, Montréal, QC H1T1C8, Canada. Electronic address: ph.pouliot@gmail.com.
authors.forename: Philippe
authors.initials: P
authors.lastname: Pouliot
mesh_terms: D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008959:Models, Neurological; D000069336:Neurovascular Coupling / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D055815:Young Adult
keywords: Deconvolution; EEG–fNIRS; Epilepsy; Hemodynamic response function; IED; Nonlinear