Abstract
This project aims to explore if stronger functional connectivity (FC) exists in the maximal BOLD response of EEG/fMRI analysis when it is concordant with seizure-onset-zone (SOZ). Twenty-six patients with drug-resistant focal epilepsy who had an EEG/fMRI and later underwent stereo-EEG implantation were included. Different types of IEDs were labeled in scalp EEG and IED-related maximal BOLD responses were evaluated separately, each constituting one study. After evaluating concordance between maximal BOLD and SOZ, twenty-seven studies were placed in the concordant group and eight in the discordant group. We evaluated the local connectivity and ipsilaterally distant connectivity difference between the maximal BOLD and the contralateral homotopic region. Significantly stronger local FC was found for the maximal BOLD in the concordant group (p < 0.05, Bonferroni corrected). 52% of the studies in the concordant group and 13% in the discordant group had a significant difference compared to healthy subjects (p < 0.05, uncorrected). The finding suggests that, when concordant with the SOZ, the maximal BOLD is more likely to have stronger local FC compared to its contralateral counterpart. This asymmetry in functional connectivity may help to noninvasively improve the specificity of EEG/fMRI analysis.
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Anonymized data not published within this article will be available upon request for qualified investigators, under approval by the research ethics board of the Montreal Neurological Institute and Hospital.
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Funding
This study is funded by Canadian Institutes of Health Research (FDN 143208), the National Key Research and Development Program (2018YFB1305101) and the National Natural Science Foundation of China (61722313).
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Written informed consent for the EEG/fMRI procedure was obtained from each patient included in the study.
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The research was approved by the Research Ethics Committee of the Montreal Neurological Institute and Hospital. The procedures used in this study adhere to the tenets of the Declaration of Helsinki.
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Written informed consent for the EEG/fMRI procedure was obtained from each patient included in the study.
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Su, J., von Ellenrieder, N., Hu, D. et al. Enhanced Regional Functional Connectivity Indicates Seizure Onset Zone. Brain Topogr 33, 545–557 (2020). https://doi.org/10.1007/s10548-020-00775-4
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DOI: https://doi.org/10.1007/s10548-020-00775-4