Non-invasive epileptic focus localization using EEG-triggered functional MRI and electromagnetic tomography

Seeck, Margitta; Lazeyras, François; Michel, CM; Blanke, Olaf; Gericke, Christian A.; Ives, John R.; Delavelle, J.; Golay, Xavier; Haenggeli, Charles-Antoine; Tribolet, Nicolas de; Landis, Théodor

doi:10.1016/s0013-4694(98)00017-0

Cited by 241 publications

(126 citation statements)

References 15 publications

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“…The LORETA algorithm allows for correct localization at a special resolution to within 1 voxel or 7 mm resolution on average. 26 Several studies provided validation for EEG-based LORETA analysis using MRI, 27 fMRI, 28 or PET. 10 …”

Section: Methodsmentioning

confidence: 99%

Subgenual Cingulate Theta Activity Predicts Treatment Response of Repetitive Transcranial Magnetic Stimulation in Participants With Vascular Depression

Narushima

McCormick²,

Yamada³

et al. 2010

Journal of Neuropsychiatry

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Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depression. Increased metabolism in the anterior cingulate cortex (ACC) is a known predictor for antidepressant response. The authors assessed whether increased theta power within the ACC predicts rTMS response in participants with vascular depression. Sixty-five participants were randomized to active or sham rTMS. Outcome was assessed using the Hamilton Depression Rating Scale. Electroencephalography was obtained, and comparisons were made among each group with a normative database using low-resolution electromagnetic tomography. Results suggest that vascular depression participants respond well to rTMS and that increased low-theta power in the subgenual ACC predicts response to rTMS.

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Section: Methodsmentioning

confidence: 99%

Subgenual Cingulate Theta Activity Predicts Treatment Response of Repetitive Transcranial Magnetic Stimulation in Participants With Vascular Depression

Narushima

McCormick²,

Yamada³

et al. 2010

Journal of Neuropsychiatry

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“…Indeed, EEG or MEG sources were estimated using either Equivalent Current Dipoles (ECDs) (Sanders et al, 1996;Bagshaw et al, 2005) or dipole scanning approaches on 3D grids (Seeck et al, 1998;Van der Meij et al, 2001;Mulert et al, 2004;Bénar et al, 2006). Consequently, the comparison metric was the Euclidian distance within the whole brain volume.…”

Section: A New Methodology To Assess Eeg-fmri Concordance During Epilmentioning

confidence: 99%

Concordance between distributed EEG source localization and simultaneous EEG-fMRI studies of epileptic spikes

et al. 2008

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In order to analyze where epileptic spikes are generated, we assessed the level of concordance between EEG source localization using distributed source models and simultaneous EEG-fMRI which measures the hemodynamic correlates of EEG activity. Data to be compared were first estimated on the same cortical surface and two comparison strategies were used: (1) MEMconcordance: a comparison between EEG sources localized with the Maximum Entropy on the Mean (MEM) method and fMRI clusters showing a significant hemodynamic response. Minimal geodesic distances between local extrema and overlap measurements between spatial extents of EEG sources and fMRI clusters were used to quantify MEM-concordance. (2) fMRI-relevance: estimation of the fMRI-relevance index α quantifying if sources located in an fMRI cluster could explain some scalp EEG data, when this fMRI cluster was used to constrain the EEG inverse problem. Combining MEM-concordance and fMRI-relevance (α) indexes, each fMRI cluster showing a significant hemodynamic response (p <0.05 corrected) was classified according to its concordance with EEG data. Nine patients with focal epilepsy who underwent EEG-fMRI examination followed by EEG recording outside the scanner were selected for this study. Among the 62 fMRI clusters analyzed (7 patients), 15 (24%) found in 6 patients were highly concordant with EEG according to both MEM-concordance and fMRI-relevance. EEG concordance was found for 5 clusters (8%) according to α only, suggesting sources missed by the MEM. No concordance with EEG was found for 30 clusters (48%) and for 10 clusters (16%) α was significantly negative, suggesting EEG-fMRI discordance. We proposed two complementary strategies to assess and classify EEG-fMRI concordance. We showed that for most patients, part of the hemodynamic response to spikes was highly concordant with EEG sources, whereas other fMRI clusters in response to the same spikes were found distant or discordant with EEG sources.Corresponding

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“…While EEG and fMRI can be acquired in separate sessions, and later combined for analysis, simultaneous acquisitions are essential when the features of interest cannot be externally controlled, as in epilepsy (Seeck et al, 1998;Gotman and Pittau, 2011), resting-state activity (Goldman et al, 2002;Britz et al, 2010) and trial-by-trial fluctuations in event-related studies (Scheeringa et al, 2011). Simultaneous acquisitions also avoid differences in spurious stimuli (Novitski et al, 2003), training or habituation effects (Debener et al, 2002) and other differences in subject performance (Boly et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous EEG–fMRI at ultra-high field: Artifact prevention and safety assessment

et al. 2015

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The simultaneous recording of scalp electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) can provide unique insights into the dynamics of human brain function, and the increased functional sensitivity offered by ultra-high field fMRI opens exciting perspectives for the future of this multimodal approach. However, simultaneous recordings are susceptible to various types of artifacts, many of which scale with magnetic field strength and can seriously compromise both EEG and fMRI data quality in recordings above 3 T. The aim of the present study was to implement and characterize an optimized setup for simultaneous EEG-fMRI in humans at 7 T. The effects of EEG cable length and geometry for signal transmission between the cap and amplifiers were assessed in a phantom model, with specific attention to noise contributions from the MR scanner coldheads. Cable shortening (down to 12 cm from cap to amplifiers) and bundling effectively reduced environment noise by up to 84% in average power and 91% in inter-channel power variability. Subject safety was assessed and confirmed via numerical simulations of RF power distribution and temperature measurements on a phantom model, building on the limited existing literature at ultra-high field. MRI data degradation effects due to the EEG system were characterized via B 0 and B 1 + field mapping on a human volunteer, demonstrating important, although not prohibitive, B 1 disruption effects. With the optimized setup, simultaneous EEG-fMRI acquisitions were performed on 5 healthy volunteers undergoing two visual paradigms: an eyes-open/eyes-closed task, and a visual evoked potential (VEP) paradigm using reversing-checkerboard stimulation. EEG data exhibited clear occipital alpha modulation and average VEPs, respectively, with concomitant BOLD signal changes. On a single-trial level, alpha power variations could be observed with relative confidence on all trials; VEP detection was more limited, although statistically significant responses could be detected in more than 50% of trials for every subject. Overall, we conclude that the proposed setup is well suited for simultaneous EEG-fMRI at 7 T.

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Non-invasive epileptic focus localization using EEG-triggered functional MRI and electromagnetic tomography

Cited by 241 publications

References 15 publications

Subgenual Cingulate Theta Activity Predicts Treatment Response of Repetitive Transcranial Magnetic Stimulation in Participants With Vascular Depression

Subgenual Cingulate Theta Activity Predicts Treatment Response of Repetitive Transcranial Magnetic Stimulation in Participants With Vascular Depression

Concordance between distributed EEG source localization and simultaneous EEG-fMRI studies of epileptic spikes

Simultaneous EEG–fMRI at ultra-high field: Artifact prevention and safety assessment

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