title: Altered Superficial White Matter on Tractography MRI in Alzheimer's Disease.
abstract: OBJECTIVE
  Superficial white matter provides extensive cortico-cortical connections. This tractography study aimed to assess the diffusion characteristics of superficial white matter tracts in Alzheimer's disease.
  
  
  METHODS
  Diffusion tensor 3T magnetic resonance imaging scans were acquired in 24 controls and 16 participants with Alzheimer's disease. Neuropsychological test scores were available in some participants. Tractography was performed by the Fiber Assignment by Continuous Tracking (FACT) method. The superficial white matter was manually segmented and divided into frontal, parietal, temporal and occipital lobes. The mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AxD) and fractional anisotropy (FA) of these tracts were compared between controls and participants with Alzheimer's disease and correlated with available cognitive tests while adjusting for age and white matter hyperintensity volume.
  
  
  RESULTS
  Alzheimer's disease was associated with increased MD (p = 0.0011), increased RD (p = 0.0019) and increased AxD (p = 0.0017) in temporal superficial white matter. In controls, superficial white matter was associated with the performance on the Montreal Cognitive Assessment, Stroop and Trail Making Test B tests, whereas in Alzheimer's disease patients, it was not associated with the performance on cognitive tests.
  
  
  CONCLUSIONS
  Temporal lobe superficial white matter appears to be disrupted in Alzheimer's disease.
authors.affiliation: Department of Medical Imaging, University of Toronto, Toronto, Ont., Canada; Memory Clinics, Division of Geriatric Medicine, Department of Medicine, Queen's University, Kingston, Ont., Canada.
authors.forename: William
authors.initials: W
authors.lastname: Reginold
authors.affiliation: Memory Clinics, Division of Geriatric Medicine, Department of Medicine, Queen's University, Kingston, Ont., Canada.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Luedke
authors.affiliation: Memory Clinics, Division of Geriatric Medicine, Department of Medicine, Queen's University, Kingston, Ont., Canada.
authors.forename: Justine
authors.initials: J
authors.lastname: Itorralba
authors.affiliation: Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Coyoacán, Mexico.
authors.forename: Juan
authors.initials: J
authors.lastname: Fernandez-Ruiz
authors.affiliation: Department of Diagnostic Radiology, Kingston General Hospital, Queen's University, Kingston, Ont., Canada.
authors.forename: Omar
authors.initials: O
authors.lastname: Islam
authors.affiliation: Memory Clinics, Division of Geriatric Medicine, Department of Medicine, Queen's University, Kingston, Ont., Canada.
authors.forename: Angeles
authors.initials: A
authors.lastname: Garcia
keywords: Cognitive function; Diffusion tensor imaging; Tractography