Diffusional kurtosis imaging reveals a distinctive pattern of microstructural alternations in idiopathic generalized epilepsy

Authors

  • C.-Y. Lee,

    1. Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
    2. Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
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  • A. Tabesh,

    1. Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
    2. Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
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  • M. V. Spampinato,

    1. Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
    2. Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
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  • J. A. Helpern,

    1. Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
    2. Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
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  • J. H. Jensen,

    1. Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
    2. Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
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  • L. Bonilha

    Corresponding author
    1. Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
    2. Division of Neurology, Department of Neurosciences, Comprehensive Epilepsy Center, Medical University of South Carolina, Charleston, SC, USA
    • L. Bonilha, Division of Neurology, Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, 3rd floor CSB, Charleston, SC 29425, USA

      Tel.: +1 843 792 3222

      Fax: +1 843 792 8626

      e-mail: bonilha@musc.edu

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Abstract

Objectives

Idiopathic generalized epilepsy (IGE) arises from paroxysmal dysfunctions of the thalamo-cortical network. One of the hallmarks of IGE is the absence of visible abnormalities on routine magnetic resonance imaging (MRI). However, recent quantitative MRI studies showed cortical–subcortical structural abnormalities in IGE, but the extent of abnormalities has been inconsistent in the literature. The inconsistencies may be associated with complex microstructural abnormalities in IGE that are not completely detectable using conventional diffusion tensor imaging methods. The goal of this study was to investigate white-matter (WM) microstructural abnormalities in patients with IGE using diffusional kurtosis imaging (DKI).

Materials and methods

We obtained DKI and volumetric T1-weighted images from 14 patients with IGE and 25 matched healthy controls. Using tract-based spatial statistics, we performed voxel-wise group comparisons in the parametric maps generated from DKI: mean diffusivity (MD), fractional anisotropy (FA), and mean kurtosis (MK), and in probabilistic maps of WM volume generated by voxel-based morphometry.

Results

We observed that conventional microstructural measures (MD and FA) revealed WM abnormalities in thalamo-cortical projections, whereas MK disclosed a broader pattern of WM abnormalities involving thalamo-cortical and cortical–cortical projections.

Conclusions

Even though IGE is traditionally considered a ‘non-lesional’ form of epilepsy, our results demonstrated pervasive thalamo-cortical WM microstructural abnormalities. Particularly, WM abnormalities shown by MK further extended into cortical–cortical projections. This suggests that the extent of microstructural abnormalities in thalamo-cortical projections in IGE may be better assessed through the diffusion metrics provided by DKI.

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