Magnetoencephalography with temporal spread imaging to visualize propagation of epileptic activity.
OBJECTIVE
We describe temporal spread imaging (TSI) that can identify the spatiotemporal pattern of epileptic activity using Magnetoencephalography (MEG).


METHODS
A three-dimensional grid of voxels covering the brain is created. The array-gain minimum-variance spatial filter is applied to an interictal spike to estimate the magnitude of the source and the time (Ta) when the magnitude exceeds a predefined threshold at each voxel. This calculation is performed through all spikes. Each voxel has the mean Ta (<Ta>) and spike number (Nsp), which is the number of spikes whose source exceeds the threshold. Then, a random resampling method is used to determine the cutoff value of Nspfor the statistically reproducible pattern of the activity. Finally, all the voxels where the source exceeds the threshold reproducibly shown on the MRI with a color scale representing <Ta>.


RESULTS
Four patients with intractable mesial temporal lobe epilepsy (MTLE) were analyzed. In three patients, the common pattern of the overlap between the propagation and the hypometabolism shown by fluorodeoxyglucose-positron emission tomography (FDG-PET) was identified.


CONCLUSIONS
TSI can visualize statistically reproducible patterns of the temporal and spatial spread of epileptic activity.


CONCLUSIONS
TSI can assess the statistical significance of the spatiotemporal pattern based on its reproducibility.
Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: sshiba@kuhp.kyoto-u.ac.jp.
Sumiya
S
Shibata
Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: matuhasi@kuhp.kyoto-u.ac.jp.
Masao
M
Matsuhashi
Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: kuny@kuhp.kyoto-u.ac.jp.
Takeharu
T
Kunieda
Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: yyamao@kuhp.kyoto-u.ac.jp.
Yukihiro
Y
Yamao
Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: inan@kuhp.kyoto-u.ac.jp.
Rika
R
Inano
Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: tkik@kuhp.kyoto-u.ac.jp.
Takayuki
T
Kikuchi
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: imamurah@kuhp.kyoto-u.ac.jp.
Hisaji
H
Imamura
Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: shig.t@kuhp.kyoto-u.ac.jp.
Shigetoshi
S
Takaya
Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: matsumot@kuhp.kyoto-u.ac.jp.
Riki
R
Matsumoto
Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: akio@kuhp.kyoto-u.ac.jp.
Akio
A
Ikeda
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: ryosuket@kuhp.kyoto-u.ac.jp.
Ryosuke
R
Takahashi
Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Graduate School of Core Ethics and Frontier Sciences, Ritsumeikan University, 56-1 Toji-in Kitamachi, Kita-ku, Kyoto 603-8577, Japan. Electronic address: t-mima@fc.ritsumei.ac.jp.
Tatsuya
T
Mima
Human Brain Research Center, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: fukuyama@kuhp.kyoto-u.ac.jp.
Hidenao
H
Fukuyama
Department of Neurosurgery, Sapporo Medical University Graduate School of Medicine, S1 W17, Chuo-ku, Sapporo, Hokkaido 060-8556, Japan. Electronic address: mikunin@sapmed.ac.jp.
Nobuhiro
N
Mikuni
Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: miy@kuhp.kyoto-u.ac.jp.
Susumu
S
Miyamoto
D000328:Adult; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Fluorodeoxyglucose F18; Magnetic resonance imaging; Magnetoencephalography; Mesial temporal lobe epilepsy; Positron-emission tomography