RT Journal Article
SR Electronic
T1 Localizing Seizure-Onset Zones in Presurgical Evaluation of Drug-Resistant Epilepsy by Electroencephalography/fMRI: Effectiveness of Alternative Thresholding Strategies
JF American Journal of Neuroradiology
JO Am. J. Neuroradiol.
FD American Society of Neuroradiology
SP 1818
OP 1824
DO 10.3174/ajnr.A3052
VO 33
IS 9
A1 M. Hauf
A1 K. Jann
A1 K. Schindler
A1 O. Scheidegger
A1 K. Meyer
A1 C. Rummel
A1 L. Mariani
A1 T. Koenig
A1 R. Wiest
YR 2012
UL http://www.ajnr.org/content/33/9/1818.abstract
AB BACKGROUND AND PURPOSE: Simultaneous EEG/fMRI is an effective noninvasive tool for identifying and localizing the SOZ in patients with focal epilepsy. In this study, we evaluated different thresholding strategies in EEG/fMRI for the assessment of hemodynamic responses to IEDs in the SOZ of drug-resistant epilepsy. MATERIALS AND METHODS: Sixteen patients with focal epilepsy were examined by using simultaneous 92-channel EEG and BOLD fMRI. The temporal fluctuation of epileptiform signals on the EEG was extracted by independent component analysis to predict the hemodynamic responses to the IEDs. We applied 3 different threshold criteria to detect hemodynamic responses within the SOZ: 1) PA, 2) a fixed threshold at P < .05 corrected for multiple comparison (FWE), and 3) FAV (4000 ± 200 activated voxels within the brain). RESULTS: PA identified the SOZ in 9 of 16 patients; FWE resulted in concordant BOLD signal correlates in 11 of 16, and FAV in 13 of 16 patients. Hemodynamic responses were detected within the resected areas in 5 (PA), 6 (FWE), and 8 (FAV) of 10 patients who remained seizure-free after surgery. CONCLUSIONS: EEG/fMRI is a noninvasive tool for the presurgical work-up of patients with epilepsy, which can be performed during seizure-free periods and is complementary to the ictal electroclinical assessment. Our findings suggest that the effectiveness of EEG/fMRI in delineating the SOZ may be further improved by the additional use of alternative analysis strategies such as FAV. BOLDblood oxygen level–dependentEEGelectroencephalographyFAVfixed numbers of activated voxelsFWEfamily-wise errorFWHMfull width at half maximumICindependent componentIEDinterictal epileptic dischargeLTLElateral temporal lobe epilepsyMTLEmesial temporal lobe epilepsyPApeak activationSOZseizure-onset zone