Utility of axial and radial diffusivity from diffusion tensor MRI as markers of neurodegeneration in amyotrophic lateral sclerosis

Nader S. Metwalli, Michael Benatar, Govind Nair, Sharon Usher, Xiaoping Hu, John D. Carew

Research output: Contribution to journalArticlepeer-review

93 Scopus citations


Objective: To investigate changes in the diffusion tensor imaging measures, axial diffusivity and radial diffusivity, in addition to the more commonly used fractional anisotropy and mean diffusivity, in patients with amyotrophic lateral sclerosis (ALS) using the voxel-based statistical analysis tool, tract based spatial statistics. Methods: We studied 12 patients with ALS and 19 normal controls using diffusion tensor imaging; tract based spatial statistics was applied to study changes in fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity values in brain white matter tracts. ALS patients were evaluated using clinical examination, administration of the revised ALS functional rating scale and measurement of the forced vital capacity. Results: In ALS patients, we found significant increases in axial diffusivity, radial diffusivity, and mean diffusivity and significant decreases in fractional anisotropy. Increases in axial diffusivity and radial diffusivity were more widespread and more prominent in the corticospinal tract than the decreases in fractional anisotropy. The decreases in fractional anisotropy were evident only in the corona radiata and genu of the corpus callosum. Conclusion: In ALS, axial diffusivity and radial diffusivity may be useful diffusion tensor imaging-derived indices to consider in addition to fractional anisotropy and mean diffusivity to aid in demonstrating neurodegenerative changes.

Original languageEnglish (US)
Pages (from-to)156-164
Number of pages9
JournalBrain research
StatePublished - Aug 21 2010
Externally publishedYes


  • Amyotrophic Lateral Sclerosis
  • Axial diffusivity
  • Diffusion Tensor Imaging
  • Magnetic Resonance Imaging
  • Radial diffusivity

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology
  • Developmental Biology
  • Molecular Biology


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