Quantitative determination of concordance in localizing epileptic focus by component-based EEG-fMRI

Area of Science:

• Neuroimaging
• Epileptology
• Medical Diagnostics

Background:

• Accurate seizure onset zone (SOZ) localization is critical for pre-surgical planning in refractory focal epilepsy.
• Current EEG-fMRI methods have limitations in considering complex epileptic pathophysiology for SOZ identification.
• Quantitative measurement of concordance between SOZ and interictal epileptiform discharge (IED)-related BOLD response is needed.

Purpose of the Study:

• To develop and validate a novel component-based EEG-fMRI approach for precise SOZ localization.
• To quantitatively measure the concordance between presumed SOZ and IED-related BOLD signals.
• To improve SOZ delineation accuracy in patients with refractory focal epilepsy.

Main Methods:

• A component-based EEG-fMRI technique was developed to measure distances between BOLD clusters and component dipole locations.
• The method utilized patient-specific high-resolution anatomical images.
• Applied to 18 epilepsy patients, it quantitatively assessed concordance and compared BOLD clusters with component dipoles.

Main Results:

• The component-based EEG-fMRI method achieved 97% localization accuracy, a significant improvement over conventional techniques.
• Distances between BOLD clusters and spikes were significantly different for concordant, partially concordant, and discordant groups (p < 0.0001).
• Full concordance was observed in 17 IED types (17.85 ± 4.69 mm), with partial concordance in 4 types (36.47 ± 8.84 mm).

Conclusions:

• Component-based EEG-fMRI demonstrates BOLD changes related to epileptic spikes in various brain regions.
• This method provides a reliable, quantitative approach to predict the SOZ in focal epilepsy.
• It is recommended for inclusion in the clinical evaluation of patients with medically resistant epilepsy.