title: Localization Accuracy of Distributed Inverse Solutions for Electric and Magnetic Source Imaging of Interictal Epileptic Discharges in Patients with Focal Epilepsy.
abstract: Distributed inverse solutions aim to realistically reconstruct the origin of interictal epileptic discharges (IEDs) from noninvasively recorded electroencephalography (EEG) and magnetoencephalography (MEG) signals. Our aim was to compare the performance of different distributed inverse solutions in localizing IEDs: coherent maximum entropy on the mean (cMEM), hierarchical Bayesian implementations of independent identically distributed sources (IID, minimum norm prior) and spatially coherent sources (COH, spatial smoothness prior). Source maxima (i.e., the vertex with the maximum source amplitude) of IEDs in 14 EEG and 19 MEG studies from 15 patients with focal epilepsy were analyzed. We visually compared their concordance with intracranial EEG (iEEG) based on 17 cortical regions of interest and their spatial dispersion around source maxima. Magnetic source imaging (MSI) maxima from cMEM were most often confirmed by iEEG (cMEM: 14/19, COH: 9/19, IID: 8/19 studies). COH electric source imaging (ESI) maxima co-localized best with iEEG (cMEM: 8/14, COH: 11/14, IID: 10/14 studies). In addition, cMEM was less spatially spread than COH and IID for ESI and MSI (p < 0.001 Bonferroni-corrected post hoc t test). Highest positive predictive values for cortical regions with IEDs in iEEG could be obtained with cMEM for MSI and with COH for ESI. Additional realistic EEG/MEG simulations confirmed our findings. Accurate spatially extended sources, as found in cMEM (ESI and MSI) and COH (ESI) are desirable for source imaging of IEDs because this might influence surgical decision. Our simulations suggest that COH and IID overestimate the spatial extent of the generators compared to cMEM.
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Room 786, Montreal, QC, H3A 2B4, Canada. marcel.heers@gmail.com.|Epilepsy Center, University Medical Center Freiburg, Freiburg, Germany. marcel.heers@gmail.com.
authors.forename: Marcel
authors.initials: M
authors.lastname: Heers
authors.affiliation: Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Montreal, Canada.
authors.forename: Rasheda A
authors.initials: RA
authors.lastname: Chowdhury
authors.affiliation: Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Montreal, Canada.
authors.forename: Tanguy
authors.initials: T
authors.lastname: Hedrich
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Room 786, Montreal, QC, H3A 2B4, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Dubeau
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Room 786, Montreal, QC, H3A 2B4, Canada.
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Hall
authors.affiliation: Physnum-Team, Centre de Recherches Mathématiques, Montreal, Canada.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Lina
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Room 786, Montreal, QC, H3A 2B4, Canada.|Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Montreal, Canada.|Physnum-Team, Centre de Recherches Mathématiques, Montreal, Canada.|Physics Department and PERFORM Centre, Concordia University, Montreal, Canada.
authors.forename: Christophe
authors.initials: C
authors.lastname: Grova
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Room 786, Montreal, QC, H3A 2B4, Canada.
authors.forename: Eliane
authors.initials: E
authors.lastname: Kobayashi
mesh_terms: D001499:Bayes Theorem; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001931:Brain Mapping; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: Electric source imaging (ESI); Electroencephalography (EEG); Focal epilepsy; Intracranial EEG; Magnetic source imaging (MSI); Magnetoencephalography (MEG)