A method for u-fiber quantification from 7 T diffusion-weighted MRI data tested in patients with nonlesional focal epilepsy

Neuroreport. 2017 May 24;28(8):457-461. doi: 10.1097/WNR.0000000000000788.


In this methods development, we present an ultra-high-field, diffusion-weighted MRI method to quantitatively assess u-fibers and use it to compare u-fiber counts in nonlesional epilepsy patients with controls. Emerging evidence implicates white matter abnormalities in nonlesional epilepsy, including the short-range, cortical-cortical connections, or u-fibers. Eight patients with nonlesional epilepsy and eight demographically matched controls underwent 7 T MRI consisting of a T1-weighted sequence (0.7 mm isotropic resolution) and high-angular-resolved diffusion-weighted MRI (1.05 mm isotropic resolution, 68 directions). MRI data were used to quantify u-fiber counts in known u-fiber populations on the basis of an atlas and fiber tractography. From tractography, connectivity matrices summarizing the u-fiber counts were computed. Quantitative group comparisons were performed on the connectivity matrices. U-fiber counts were found to be lower on average in patients with epilepsy than in healthy controls. The results indicate that the density or the number of u-fibers is reduced in patients with nonlesional epilepsy. Future work will focus on histological validation and determining whether differences in u-fiber counts can be used clinically to noninvasively identify seizure-onset zones.

MeSH terms

  • Adult
  • Brain Mapping
  • Diffusion Magnetic Resonance Imaging / methods*
  • Epilepsies, Partial / diagnostic imaging*
  • Epilepsies, Partial / pathology*
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Neural Pathways / diagnostic imaging
  • Neural Pathways / pathology
  • White Matter / diagnostic imaging*
  • White Matter / pathology*