Frédéric Grouiller1, João Jorge2,3, Francesca Pittau4, Wietske van der Zwaag5,6, Giannina Rita Iannotti7, Christoph Martin Michel7, Serge Vulliémoz4, Maria Isabel Vargas8, François Lazeyras9. 1. Department of Radiology and Medical Informatics, University of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland. frederic.grouiller@unige.ch. 2. Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. 3. ISR-Lisboa/LARSyS and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal. 4. EEG and Epilepsy Unit, Department of Neurology, Geneva University Hospitals, Geneva, Switzerland. 5. Biomedical Imaging Research Center, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. 6. Spinoza Centre for Neuroimaging, Amsterdam, The Netherlands. 7. Functional Brain Mapping Laboratory, Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland. 8. Division of Neuroradiology, Geneva University Hospitals, Geneva, Switzerland. 9. Department of Radiology and Medical Informatics, University of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211, Geneva 14, Switzerland.
Abstract
OBJECTIVES: The aim of this study was to demonstrate that eloquent cortex and epileptic-related hemodynamic changes can be safely and reliably detected using simultaneous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) recordings at ultra-high field (UHF) for clinical evaluation of patients with epilepsy. MATERIALS AND METHODS: Simultaneous EEG-fMRI was acquired at 7 T using an optimized setup in nine patients with lesional epilepsy. According to the localization of the lesion, mapping of eloquent cortex (language and motor) was also performed in two patients. RESULTS: Despite strong artifacts, efficient correction of intra-MRI EEG could be achieved with optimized artifact removal algorithms, allowing robust identification of interictal epileptiform discharges. Noise-sensitive topography-related analyses and electrical source localization were also performed successfully. Localization of epilepsy-related hemodynamic changes compatible with the lesion were detected in three patients and concordant with findings obtained at 3 T. Local loss of signal in specific regions, essentially due to B 1 inhomogeneities were found to depend on the geometric arrangement of EEG leads over the cap. CONCLUSION: These results demonstrate that presurgical mapping of epileptic networks and eloquent cortex is both safe and feasible at UHF, with the benefits of greater spatial resolution and higher blood-oxygenation-level-dependent sensitivity compared with the more traditional field strength of 3 T.
OBJECTIVES: The aim of this study was to demonstrate that eloquent cortex and epileptic-related hemodynamic changes can be safely and reliably detected using simultaneous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) recordings at ultra-high field (UHF) for clinical evaluation of patients with epilepsy. MATERIALS AND METHODS: Simultaneous EEG-fMRI was acquired at 7 T using an optimized setup in nine patients with lesional epilepsy. According to the localization of the lesion, mapping of eloquent cortex (language and motor) was also performed in two patients. RESULTS: Despite strong artifacts, efficient correction of intra-MRI EEG could be achieved with optimized artifact removal algorithms, allowing robust identification of interictal epileptiform discharges. Noise-sensitive topography-related analyses and electrical source localization were also performed successfully. Localization of epilepsy-related hemodynamic changes compatible with the lesion were detected in three patients and concordant with findings obtained at 3 T. Local loss of signal in specific regions, essentially due to B 1 inhomogeneities were found to depend on the geometric arrangement of EEG leads over the cap. CONCLUSION: These results demonstrate that presurgical mapping of epileptic networks and eloquent cortex is both safe and feasible at UHF, with the benefits of greater spatial resolution and higher blood-oxygenation-level-dependent sensitivity compared with the more traditional field strength of 3 T.
Entities:
Keywords:
EEG–fMRI; Epilepsy; Presurgical mapping; Ultra-high field
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