Contribution of subtraction ictal SPECT coregistered to MRI to epilepsy surgery: a multicenter study.
OBJECTIVE
A multicenter prospective study was performed to assess the additional value of a subtraction ictal SPECT coregistered to MRI (SISCOM) technique to traditional side-by-side comparison of ictal- and interictal SPECT images in epilepsy surgery.


METHODS
One hundred and twenty-three patients with temporal and extratemporal lobe epilepsy who had undergone epilepsy surgery after evaluation of scalp ictal and interictal electroencephalogram (EEG), MRI, and ictal and interictal SPECT scans were followed up in terms of postsurgical outcome for a period of at least 1 year. Three reviewers localized the epileptogenic focus using ictal and interictal SPECT images first by side-by-side comparison and subsequently by SISCOM. Concordance of the localization of the epileptogenic focus by SPECT diagnosis with the surgical site and inter-observer agreement between reviewers was compared between side-by-side comparison and SISCOM. Logistic regression analysis was performed in predicting the surgical outcome with the dependent variable being the achievement of a good postsurgical outcome and the independent variables using the SISCOM, side-by-side comparison of ictal and interictal SPECT images, MRI, and scalp ictal EEG.


RESULTS
The SISCOM presented better concordance in extratemporal lobe epilepsy and less concordance in temporal lobe epilepsy than side-by-side comparison. Inter-observer concordance was higher in SISCOM than in side-by-side comparison. Much higher concordance of the epileptogenic focus by SPECT diagnosis with the surgical site was obtained in patients with good surgical outcome than in those with poor surgical outcome. These differences in concordance between good and poor surgical outcomes were greater in SISCOM than in side-by-side comparison. Logistic regression analysis showed the highest odds ratio of 12.391 (95% confidence interval; 3.319, 46.254) by SISCOM evaluation for concordance of the epileptogenic focus with the surgical site in predicting good surgical outcome.


CONCLUSIONS
A SISCOM technique of ictal and interictal SPECT images provides higher predictive value of good surgical outcome and more reliability on the diagnosis of the epileptogenic focus than side-by-side comparison in medically intractable partial epilepsy.
Department of Nuclear Medicine, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka, Saitama 350-1298, Japan. matsudah@saitama-med.ac.jp
Hiroshi
H
Matsuda
Kazumi
K
Matsuda
Fumihiro
F
Nakamura
Shigeki
S
Kameyama
Hiroshi
H
Masuda
Taisuke
T
Otsuki
Hideyuki
H
Nakama
Hiroshi
H
Shamoto
Nobukazu
N
Nakazato
Masahiro
M
Mizobuchi
Joji
J
Nakagawara
Takato
T
Morioka
Yasuo
Y
Kuwabara
Hideo
H
Aiba
Masayuki
M
Yano
Yeong-Jin
YJ
Kim
Hiroyuki
H
Nakase
Ichiei
I
Kuji
Yoko
Y
Hirata
Sunao
S
Mizumura
Etsuko
E
Imabayashi
Noriko
N
Sato
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging* / Q000601:surgery* / Q000628:therapy; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D013382:Subtraction Technique; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome