A new approach to structural integrity assessment based on axial and radial diffusivities

Claudia A M Wheeler-Kingshott, Olga Ciccarelli, Torben Schneider, Daniel C. Alexander, Mara Cercignani

Research output: Contribution to journalArticlepeer-review


This study describes a method for performing diffusivity measures along and across a specific direction, derived from white matter in healthy controls. The diffusion tensor (DT) assigns a principal eigenvector (v1) and eigenvalue (axial diffusivity, dax) to each voxel. The average of the second and third eigenvalues is the radial diffusivity, drad•v1 may be affected by pathology, therefore when comparing d ax and drad in patients one has to consider the direction of the measurement and underlying anatomy. Here we created a representative super-DT dataset, DT rref, whose eigenvector, v1,ref, was considered the most likely direction of diffusivity per voxel. We defined the projected axial diffusivity, dp-ax, as the projection of individual DTs along v1,ref and the projected radial diffusivity, dp-rad, as the average of the projections along the second and third eigenvectors of DTref. The projected diffusivities are promising new parameters for studying white matter pathology.

Original languageEnglish
Pages (from-to)85-90
Number of pages6
JournalFunctional Neurology
Issue number2
Publication statusPublished - Oct 2012


  • Axial diffusivity
  • Diffusion tensor
  • DTI
  • Eigenvalues
  • Radial diffusivity
  • Template

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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