Diffusion tensor imaging identifies changes in normal-appearing white matter within the epileptogenic zone in tuberous sclerosis complex

SummaryPurposeTo 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.MethodsTwelve 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 (λ||) and radial diffusivity (λ⊥) were calculated.Results26 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), λ|| (p = 0.672) and λ⊥ (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 λ⊥ (p = 0.011) was higher than non-epileptogenic zone. There were no significant differences between MD (p = 0.110) and λ|| (p = 0.735) of normal-appearing subcortical white matter within the epileptogenic and non-epileptogenic zone.ConclusionDTI 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.