Imaging haemodynamic changes related to seizures: comparison of EEG-based general linear model, independent component analysis of fMRI and intracranial EEG.
BACKGROUND
Simultaneous EEG-fMRI can reveal haemodynamic changes associated with epileptic activity which may contribute to understanding seizure onset and propagation.


METHODS
Nine of 83 patients with focal epilepsy undergoing pre-surgical evaluation had seizures during EEG-fMRI and analysed using three approaches, two based on the general linear model (GLM) and one using independent component analysis (ICA): The results were compared with intracranial EEG.


RESULTS
The canonical GLM analysis revealed significant BOLD signal changes associated with seizures on EEG in 7/9 patients, concordant with the seizure onset zone in 4/7. The Fourier GLM analysis revealed changes in BOLD signal corresponding with the results of the canonical analysis in two patients. ICA revealed components spatially concordant with the seizure onset zone in all patients (8/9 confirmed by intracranial EEG).


CONCLUSIONS
Ictal EEG-fMRI visualises plausible seizure related haemodynamic changes. The GLM approach to analysing EEG-fMRI data reveals localised BOLD changes concordant with the ictal onset zone when scalp EEG reflects seizure onset. ICA provides additional information when scalp EEG does not accurately reflect seizures and may give insight into ictal haemodynamics.
Thornton
R C
RC
Dept of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London WC1N 3BG, National Society for Epilepsy MRI Unit, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK.
Rodionov
R
R
Laufs
H
H
Vulliemoz
S
S
Vaudano
A
A
Carmichael
D
D
Cannadathu
S
S
Guye
M
M
McEvoy
A
A
Lhatoo
S
S
Bartolomei
F
F
Chauvel
P
P
Diehl
B
B
De Martino
F
F
Elwes
R D C
RD
Walker
M C
MC
Duncan
J S
JS
Lemieux
L
L
D001931:Brain Mapping / Q000379:methods; D002560:Cerebrovascular Circulation; D003198:Computer Simulation; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D012640:Seizures / Q000503:physiopathology*; D012680:Sensitivity and Specificity
D010100:Oxygen