Subcortical alterations in tissue microstructure adjacent to focal cortical dysplasia: detection at diffusion-tensor MR imaging by using magnetoencephalographic dipole cluster localization.
ABSTRACT To determine whether changes at diffusion-tensor magnetic resonance (MR) imaging were present in children with intractable epilepsy and focal cortical dysplasia (FCD) in (a) subcortical white matter subjacent to MR imaging-visible areas of FCD, (b) subcortical white matter beyond the MR imaging-visible abnormality but subjacent to a magnetoencephalographic (MEG) dipole cluster, and (c) deep white matter tracts.
The study protocol had institutional research ethics board approval, and written informed consent was obtained. Fifteen children with FCD and intractable epilepsy (mean age, 11.6 years; range, 3.6-18.3 years) underwent diffusion-tensor MR imaging and MEG. Regions of interest were placed in (a) the subcortical white matter subjacent to the MR imaging-visible abnormality, as well as the contralateral side; (b) the subcortical white matter beyond the MR imaging-visible abnormality but subjacent to a MEG dipole cluster, as well as the contralateral side; and (c) deep white matter tracts projecting to or from the MR imaging-visible FCD, as well as the contralateral side. Fractional anisotropy (FA), mean diffusivity, and eigenvalues (lambda(1), lambda(2), lambda(3)) were evaluated.
Eleven of 15 children had MEG dipole clusters, and four children had MEG scatter. There were significant differences in FA, mean diffusivity, lambda(2), and lambda(3) of the subcortical white matter subjacent to the MR imaging-visible FCD (P < .001 for all), as well as that beyond the MR imaging-visible FCD but subjacent to a MEG dipole cluster (P = .001, P = .036, P < .001, and P = .002, respectively), compared with the contralateral side. There were also significant differences in FA (P < .001), mean diffusivity (P = .008), lambda(2) (P < .001), and lambda(3) (P = .001) of the deep white matter tracts projecting to or from the MR imaging-visible FCD compared with the contralateral side.
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.
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ABSTRACT: Purpose: This study was conducted to assess the clinical relevance of diffusion tensor tractography (DTT) in pre- and post-operative evaluations of childhood epilepsy surgery. Materials and Methods: Seventy-two patients who received epilepsy surgery between March 2004 and July 2008 were retrospectively analyzed (M : F=40 : 32, ages of 3 months to 24 years, mean age=8.9 years). DTT was performed using a 3.0 T scanner and single-shot spin-echo echo-planar imaging with 32-different diffusion gradient directions. We reviewed the data focusing on the type of surgery, final pathological diagnosis, and how the DTT data were clinically used. Results: The most common form of childhood epilepsy surgery was complete resection of an epileptogenic lesion (n=52, 72.2%). The reported etiologies included cortical dysplasia (n=32, 44.4%), hippocampal sclerosis (n=9, 12.5%), brain tumors (n=7, 9.7%), and non-pathologic lesions (n=4, 5.6%) in the final diagnoses. Twenty-one dysplastic cortexes and four brain tumors involved an approximal relationship with the corticospinal tract (n=18), optic radiation (n=2), and arcuate fasciculus (n=5). Additionally, although DTT demonstrated white matter tracts clearly, DTT in the hippocampal sclerosis did not provide any additional information. In cases of callosotomy (n=18, 25%), post-operative DTT was utilized for the evaluation of complete resection in all patients. DTT information was not used in functional hemispherectomy (n=2, 2.8%). Conclusion: Preoperatively, DTT was a useful technique in cases of cortical dysplasia and brain tumors, and in cases with callosotomy, postoperatively. DTT should be included among the routine procedures performed in management of epilepsy.Yonsei medical journal 01/2013; 54(1):21-7. · 0.77 Impact Factor
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ABSTRACT: INTRODUCTION: The contribution of radial migration lines (RMLs) to the neuroanatomical and neurocognitive phenotype of tuberous sclerosis complex (TSC) is unclear. The aim of this study was to perform a comprehensive evaluation of the neuroradiological phenotype of TSC, distinguishing RMLs from normal-appearing white matter (NAWM) using diffusion tensor imaging (DTI) and volumetric fluid-attenuated inversion recovery imaging. METHODS: Magnetic resonance images of 30 patients with TSC were evaluated. The frequencies of RMLs, tubers, and subependymal nodules (SENs) were determined for every hemispheric lobe. Cerebellar lesions and subependymal giant cell tumors were counted. DTI metrics were obtained from the NAWM of every hemispheric lobe and from the largest RML and tuber. Analyses of variance and correlations were performed to investigate the associations between neuroanatomical characteristics and relationships between RML frequency and neurocognitive outcomes. NAWM DTI metrics were compared with measurements of 16 control patients. RESULTS: A mean of 47 RMLs, 27 tubers, and 10 SENs were found per patient, and the frequencies of these lesions were strongly correlated (p < 0.001). RML fractional anisotropy and mean diffusivity were strongly inversely correlated (p = 0.003). NAWM DTI metrics were similar to the controls (p = 0.26). RML frequency was strongly associated with age of seizure onset (p = 0.003), intelligence outcomes (p = 0.01), and level of autistic features (p = 0.007). CONCLUSION: A detailed neuroradiological phenotype is presented, showing that RMLs are the most frequent neuroanatomical lesion, are responsible for white matter DTI abnormalities, and are strongly associated with age of seizure onset, intelligence outcomes, and level of autistic features.Neuroradiology 05/2013; · 2.70 Impact Factor
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ABSTRACT: BACKGROUND: Despite pharmacological and surgical interventions, some children with periventricular nodular heterotopia (PNH) remain refractory to treatment, which suggests more diffuse pathology potentially involving perilesional white matter. OBJECTIVE: The purpose of this study was to evaluate MR diffusion tensor imaging (MRDTI) metrics within perilesional white matter in children with PNH. MATERIALS AND METHODS: Six children with PNH (four boys; average age 3.2 years, range 2 months to 6 years) were studied with MRDTI at 3 T. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were quantified within perilesional white matter at distances of 5 mm, 10 mm, 15 mm, and 20 mm from focal areas of PNH and compared to location-matched ROIs in six healthy control patients (two boys, average age 3.3 years, range 2-6 years). Statistical significance was set at an overall level of α = 0.05, corrected for multiple comparisons. RESULTS: Perilesional white matter showed significantly decreased fractional anisotropy and elevated mean and radial diffusivity at all evaluated distances. No significant differences in axial diffusivity were detected at any distance. CONCLUSION: PNH is associated with microstructural white matter abnormalities as indicated by abnormal perilesional MRDTI metrics detectable at least 20 mm from visible nodular lesions.Pediatric Radiology 03/2013; · 1.57 Impact Factor