title: Optimal optode montage on electroencephalography/functional near-infrared spectroscopy caps dedicated to study epileptic discharges.
abstract: Functional near-infrared spectroscopy (fNIRS), acquired simultaneously with electroencephalography (EEG), allows the investigation of hemodynamic brain responses to epileptic activity. Because the presumed epileptogenic focus is patient-specific, an appropriate source/detector (SD) montage has to be reconfigured for each patient. The combination of EEG and fNIRS, however, entails several constraints on montages, and finding an optimal arrangement of optodes on the cap is an important issue. We present a method for computing an optimal SD montage on an EEG/fNIRS cap that focuses on one or several specific brain regions; the montage maximizes the spatial sensitivity. We formulate this optimization problem as a linear integer programming problem. The method was evaluated on two EEG/fNIRS caps. We simulated absorbers at different locations on a head model and generated realistic optical density maps on the scalp. We found that the maps of optimal SD montages had spatial resolution properties comparable to those of regular SD arrangements for the whole head with significantly fewer sensors than regular SD arrangements. In addition, we observed that optimal montages yielded improved spatial density of fNIRS measurements over the targeted regions together with an increase in signal-to-noise ratio.
authors: McGill University, Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, H3A 2B4, Québec, Canada.
authors: Alexis
authors: A
authors: Machado
authors: GERAD, École des HEC, Montréal, H3T 2A7, Québec, CanadaeUniversité du Québec à Montréal, Département d'informatique, H3C 3P8 Québec Canada.
authors: Odile
authors: O
authors: Marcotte
authors: École de Technologie Supérieure de l'Université du Québec, H3C 1K3, Québec, Canada.
authors: Jean Marc
authors: JM
authors: Lina
authors: McGill University, Montreal Neurological Institute, Department of Neurology and Neurosurgery, H3A 2B4, Québec, Canada.
authors: Eliane
authors: E
authors: Kobayashi
authors: McGill University, Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, H3A 2B4, Québec, CanadabMcGill University, Montreal Neurological Institute, Department of Neurology and Neurosurgery, H3A 2B4, Québec, Canada.
authors: Christophe
authors: C
authors: Grova
mesh_terms: D001921:Brain / Q000098:blood supply / Q000503:physiopathology; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D004827:Epilepsy / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared / Q000379:methods*