With use of MEG dipole clusters to localize the epileptogenic zone, diffusion-tensor imaging can help identify alterations in tissue microstructure beyond the MR imaging-visible FCD.

BACKGROUND AND PURPOSE:The subplate layer and intermediate zone are the precursors for neonatal white matter. The aims of this study were to evaluate 1) T1 and T2 signal intensity, and 2) FA of subplate and intermediate zone in postmortem fetuses and correlate with histology, and 3) T2 signal intensity of subplate and intermediate zone on antenatal MR imaging.

BACKGROUND AND PURPOSE:Children with new-onset seizures may have antecedent neurobiologic alterations that predispose them to developing seizures. Our aim was to evaluate hippocampal and thalamic volumes and lobar cortical thickness of children with new-onset seizures.

SUMMARY:We evaluated the DTI changes in the deep gray nuclei and dorsal brain stem, which demonstrated abnormal T2 and/or diffusion signal intensity, in 6 patients with infantile spasm treated with vigabatrin compared with 6 age-matched controls. Regions of interest were placed in the globi pallidi, thalami, and dorsal brain stem; FA, trace, D ʈ , and D Ќ were measured. Patients on vigabatrin had significantly lower FA in both globi pallidi (P ϭ .01) and the dorsal brain stem (P Ͻ .01), significantly lower trace in both globi pallidi (P ϭ .01) and the thalami (P ϭ .02 and .01 for right and left, respectively), and significantly lower D ʈ in both globi pallidi (P Յ .01), the thalami (P Ͻ .01), and the dorsal brain stem (P ϭ .03). There were no significant differences in D Ќ of the globi pallidi, thalami, or dorsal brain stem in patients compared with controls. The findings suggest that axonal changes play a greater role in the observed abnormal signal intensity, with lesser contribution from myelin changes.ABBREVIATIONS: D ʈ ϭ axial diffusivity; D Ќ ϭ radial diffusivity; DB ϭ dorsal brain stem; DTI ϭ diffusion tensor imaging; FA ϭ fractional anisotropy; GABA ϭ ␥-aminobutyric acid; GP ϭ globi pallidi; ICC ϭ intraclass correlation coefficient; IS ϭ infantile spasm; L ϭ left; MRI ϭ MR imaging; R ϭ right; Thal ϭ thalami; TSC ϭ tuberous sclerosis complex; VGB ϭ vigabatrin; VGB-Pt ϭ patients on vigabatrin therapy with abnormal T2 and/or diffusion signal intensity on MR imaging V igabatrin is a structural analog of GABA, which irreversibly inhibits GABA-transaminase, increasing brain levels of GABA. Vigabatrin has been used to treat infantile spasms and refractory complex partial seizures, and clinical trials have shown that vigabatrin may provide rapid reduction in seizure frequency and has allowed some patients to become seizurefree.1 Vigabatrin was generally reported as a well-tolerated drug; however, visual disturbances, manifested as visual blurring and constriction of visual fields, were noted in some patients treated with vigabatrin. In addition, animal studies have raised concerns that prolonged administration of vigabatrin induced intramyelin edema. [2][3][4] Recently, human studies have described reversible MR imaging abnormalities characterized by T2-weighted hyperintensities and/or restricted diffusion in the globi pallidi, thalami, dorsal pons, and midbrain in approximately 20%-30% of patients with infantile spasm. 5-7Young age and high dose appeared to be risk factors for the development of these reversible changes in the deep gray nuclei and brain stem. [5][6][7] The underlying microstructural changes responsible for the T2 and diffusion changes in the human brain are unknown. However, on the basis of animal studies, we postulated that the abnormal T2 signal intensity and diffusion restriction in the deep gray nuclei and dorsal brain stem were related to intramyelin edema.DTI can be used to indirectly evaluate the integrity of the axonal microenvironment by assessing the diffusion of water molecules and i...

BACKGROUND AND PURPOSE:Patients with MR imaging-negative epilepsy could have subtle FCD. Our aim was to determine if structural changes could be identified by using DTI in children with intractable epilepsy, from MR imaging-visible FCD and MR imaging-negative localization-related epilepsy, that were concordant with the epileptogenic zone as defined by using the MEG dipole cluster.

BACKGROUND AND PURPOSE:The presence of normal fetal cerebral lamination of the germinal matrix, intermediate zone, subplate layer, and cortex can be used as a marker of normal fetal cerebral development. Our aim was to compare postmortem MR imaging assessment of normal and abnormal fetal cerebral lamination on T1-and T2-weighted images with histopathology.