Simultaneous Intracranial EEG-fMRI for the Study of Epilepsy in Humans at 3.0 T
Abstract
Neuroimaging plays in an important role in the diagnosis and treatment of epilepsy. In this work, a novel multi-modal technique for imaging the hemodynamic correlates of epileptic activity is explored. Simultaneous intracranial electroencephalography functional magnetic resonance imaging (iEEG-fMRI) combines the temporal precision of intracranial EEG with the high spatial resolution of fMRI. Applying this technique in patients with epilepsy, it was found the fMRI signal changes associated with interictal epileptiform discharges (IEDs) are patient-specific rather than consistent across subjects, implying that analyses of iEEG-fMRI data should allow for this variability through flexible analysis methods. In addition, significant fMRI activity was found adjacent to the electrode generating the IEDs in the majority of patients studied. It was determined that a minimum of 30 IEDs are necessary to detect fMRI activity near the active electrode, and the addition of more discharges to the analysis eliminates non-IED related noise providing more precise localization. Lastly, focusing exclusively on patients with mesial temporal lobe IEDs, two distinct patterns of fMRI activity were found: fMRI activity primarily localized to the active mesial temporal lobe, and widespread bilateral fMRI activity throughout the cortex. Notably, the patients with widespread activity were found to have fewer secondarily generalized seizures implying that the widespread fMRI activity may act to inhibit these seizures. In summary, simultaneous iEEG-fMRI is a viable technique for the study of epilepsy and may aid in the localization of the source of seizures and provide new insight into the networks involved in epileptic activity.
Description
Keywords
Medicine and Surgery, Radiology
Citation
Beers, C. (2015). Simultaneous Intracranial EEG-fMRI for the Study of Epilepsy in Humans at 3.0 T (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27790