Page 205 - MEGIN Book Of Abstracts - 2023

statistics (NBS) and with the clustering coefficient (CC), solutions (Ave) can improve localization accuracy. We
nodal efficiency (NE), betweenness centrality (BC), and analyzed dMSI of 206 IEDs derived from magnetoen-
eigenvector centrality (EVC). NBS identified a subnet- cephalography recordings in 28 focal epilepsy patients
work primarily composed of right intra-hemispheric who had a well-defined focus determined through
connections. Significantly different (p < .05) nodes intracranial EEG (iEEG), epileptogenic MRI lesions or
were primarily in the right hemisphere for the CC and surgical resection. dMSI accuracy and spatial properties
NE and primarily in the left hemisphere for the BC and were quantitatively estimated as: (a) distance from the
EVC. These results indicate that intra-hemispheric MEG epilepsy focus, (b) reproducibility, (c) spatial dispersion
networks may be incorporated in the diagnosis and (SD), (d) map extension, and (e) effect of thresholding
lateralization of focal epilepsy. on map properties. Clinical performance was excellent
for all methods (median distance from the focus MNE
Keywords: focal epilepsy, functional connectivity, graph = 2.4 mm; sLORETA = 3.5 mm; cMEM = 3.5 mm; dSPM =
measures, intra-hemispheric brain networks, machine 6.8 mm, Ave = 0 mm). Ave showed the lowest distance
learning, magnetoencephalography, network-based between the map maximum and epilepsy focus (Dmin
statistics lower than cMEM, MNE, and dSPM, p = .021, p = .008, p
< .001, respectively). cMEM showed the best spatial fea-
Human brain mapping (2020), Vol. 41, No. 11 (32400923) tures, with lowest SD outside the focus (SD lower than
(10 citations) all other methods, p < .001 consistently) and high con-
trast between the generator and surrounding regions.
The average map Ave provided the best localization
Accuracy and spatial properties of distributed accuracy, whereas cMEM exhibited the lowest amount
magnetic source imaging techniques in the of spurious distant activity. dMSI techniques have the
investigation of focal epilepsy patients (2020) potential to significantly improve identification of iEEG
targets and to guide surgical planning, especially when
Pellegrino, Giovanni; Hedrich, Tanguy; Porras- multiple methods are combined.
Bettancourt, Manuel; Lina, Jean-Marc; Aydin, Ümit; Hall,
Jeffery; Grova, Christophe; Kobayashi, Eliane Keywords: MEG, interictal epileptiform discharges, inverse
problem, magnetic source imaging, presurgical evalua-
Department of Multimodal Functional Imaging Lab, Biomed- tion, source localization, spike
ical Engineering, McGill University, Montreal, Quebec, Can-
ada; Department of Neurology and Neurosurgery, Montreal Human brain mapping (2020), Vol. 41, No. 11 (32386115)
Neurological Institute, McGill University, Montreal, Quebec, (16 citations)
Canada; Centre de Recherches Mathematiques, Montréal,
Quebec, Canada; Physics Department and PERFORM Centre,
Concordia University, Montreal, Quebec, Canada Genuine cross-frequency coupling networks
in human resting-state electrophysiological
ABSTRACT Source localization of interictal epileptiform recordings (2020)
discharges (IEDs) is clinically useful in the presurgical
workup of epilepsy patients. We aimed to compare the Siebenhühner, Felix; Wang, Sheng H; Arnulfo, Gabriele;
performance of four different distributed magnetic Lampinen, Anna; Nobili, Lino; Palva, J Matias; Palva,
source imaging (dMSI) approaches: Minimum norm es- Satu
timate (MNE), dynamic statistical parametric mapping
(dSPM), standardized low-resolution electromagnetic BioMag Laboratory, HUS Medical Imaging Center, Helsinki,
tomography (sLORETA), and coherent maximum entro- Finland; Doctoral Program Brain & Mind, University of
py on the mean (cMEM). We also evaluated whether a Helsinki, Finland; Department of Informatics, Bioengineer-
simple average of maps obtained from multiple inverse ing, Robotics and System engineering, University of Genoa,

 ontents  Index 184
C