Diffusion tensor imaging identifies changes in normal-appearing white matter within the epileptogenic zone in tuberous sclerosis complex.
OBJECTIVE
To evaluate diffusion tensor imaging (DTI) indices of (i) cortical tubers and (ii) normal-appearing subcortical white matter adjacent to cortical tubers within the epileptogenic zone and non-epileptogenic zone.


METHODS
Twelve children with tuberous sclerosis complex underwent MRI, DTI and magnetoencephalography (MEG). Regions of interest (ROIs) were placed within cortical tubers and normal-appearing subcortical white matter adjacent to cortical tubers within MEG identified epileptogenic zone and non-epileptogenic zone. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (lambda(parallel)) and radial diffusivity (lambda(perpendicular)) were calculated.


RESULTS
26 out of 104 cortical tubers were in the epileptogenic zone. FA of cortical tubers in the epileptogenic zone was significantly lower than non-epileptogenic zone (p=0.015). There were no significant differences between MD (p=0.896), lambda(parallel) (p=0.672) and lambda(perpendicular) (p=0.651) of cortical tubers in the epileptogenic and non-epileptogenic zone. In normal-appearing subcortical white matter within the epileptogenic zone, FA was lower (p=0.001) and lambda(perpendicular) (p=0.011) was higher than non-epileptogenic zone. There were no significant differences between MD (p=0.110) and lambda(parallel) (p=0.735) of normal-appearing subcortical white matter within the epileptogenic and non-epileptogenic zone.


CONCLUSIONS
DTI changes in normal-appearing white matter within the epileptogenic zone could represent abnormal white matter related to MRI-occult dysplastic cortex or ictal/interictal activity.
Diagnostic Imaging, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada. Elysa.Widjaja@sickkids.ca
Elysa
E
Widjaja
Gustavo
G
Simao
Sina Zarei
SZ
Mahmoodabadi
Ayako
A
Ochi
O Carter
OC
Snead
James
J
Rutka
Hiroshi
H
Otsubo
D000293:Adolescent; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D014402:Tuberous Sclerosis / Q000473:pathology*