OBJECTIVEUsing the functional connectivity analysis based on the underlying neurophysiological characteristic that epileptic discharges can induce change of brain default mode, to develop a technique for epileptogenic localization using functional MRI (fMRI) without simultaneous electroencephalography (EEG).

METHODSA data-driven method that jointly employed independent component analysis and functional connectivity analysis was used for the resting functional MRI data analysis of 12 focal epileptic patients. The independent components were ranged according to the coefficients of the negative correlation between independent component time course and the signal temporal course in the region of posterior cingulate cortex. The results were comparatively studied with simultaneous EEG-fMRI.

RESULTSIn the 10 successful results from 12 patients underwent EEG-fMRI examination, the outcomes of eight subjects were concordant with pathological foci. While the results of all 10 patients processed by data-driven method were concordant with pathological foci, besides the other patients who failed to perform EEG-fMRI examination. Meanwhile, the default mode was well mapped in all patients.

CONCLUSIONSThe default mode-based functional connectivity analysis can localize the epileptogenic foci effectively without simultaneous EEG, besides to detect the default mode of epileptic patients.