High b-value diffusion tractography: Abnormal axonal network organization associated with medication-refractory epilepsy
Ezequiel Gleichgerrcht,
Simon S. Keller,
Lorna Bryant,
Hunter Moss,
Tanja S. Kellermann,
Shubhabrata Biswas,
Anthony G. Marson,
Janina Wilmskoetter,
Jens H. Jensen,
Leonardo Bonilha
Affiliations
Ezequiel Gleichgerrcht
Department of Neurology, Medical University of South Carolina, Charleston, SC, USA; Corresponding author.
Simon S. Keller
Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, UK; The Walton Centre NHS Foundation Trust, Liverpool, UK
Lorna Bryant
Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, UK
Hunter Moss
Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
Tanja S. Kellermann
Department of Neurology, Medical University of South Carolina, Charleston, SC, USA
Shubhabrata Biswas
The Walton Centre NHS Foundation Trust, Liverpool, UK
Anthony G. Marson
Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, UK; The Walton Centre NHS Foundation Trust, Liverpool, UK
Janina Wilmskoetter
Department of Neurology, Medical University of South Carolina, Charleston, SC, USA
Jens H. Jensen
Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, USA
Leonardo Bonilha
Department of Neurology, Medical University of South Carolina, Charleston, SC, USA
Diffusion magnetic resonance imaging (dMRI) tractography has played a critical role in characterizing patterns of aberrant brain network reorganization among patients with epilepsy. However, the accuracy of dMRI tractography is hampered by the complex biophysical properties of white matter tissue. High b-value diffusion imaging overcomes this limitation by better isolating axonal pathways. In this study, we introduce tractography derived from fiber ball imaging (FBI), a high b-value approach which excludes non-axonal signals, to identify atypical neuronal networks in patients with epilepsy. Specifically, we compared network properties obtained from multiple diffusion tractography approaches (diffusion tensor imaging, diffusion kurtosis imaging, FBI) in order to assess the pathophysiological relevance of network rearrangement in medication-responsive vs. medication-refractory adults with focal epilepsy. We show that drug-resistant epilepsy is associated with increased global network segregation detected by FBI-based tractography. We propose exploring FBI as a clinically feasible alternative to quantify topological changes that could be used to track disease progression and inform on clinical outcomes.
