title: [Tractography of the uncinate fasciculus and the posterior cingulate fasciculus in patients with mild cognitive impairment and Alzheimer disease].
abstract: BACKGROUND
  Brain tractography is a non-invasive medical imaging technique which enables in vivo visualisation and various types of quantitative studies of white matter fibre tracts connecting different parts of the brain. We completed a quantitative study using brain tractography with diffusion tensor imaging in patients with mild cognitive impairment, patients with Alzheimer disease, and normal controls, in order to analyse the reproducibility and validity of the results.
  
  
  METHODS
  Fractional anisotropy (FA) and mean diffusivity (MD) were measured across the uncinate fasciculus and the posterior cingulate fasciculus in images, obtained from a database and a research centre, representing 52 subjects distributed among the 3 study groups. Two observers took the measurements twice in order to evaluate intra- and inter-observer reproducibility.
  
  
  RESULTS
  Measurements of FA and MD of the uncinate fasciculus delivered an intraclass correlation coefficient above 0.9; ICC was above 0.68 for the posterior cingulate fasciculus. Patients with Alzheimer disease showed lower values of FA and higher MD values in the right uncinate fasciculus in images from the research centre. A comparison of the measurements from the 2 centres revealed significant differences.
  
  
  CONCLUSIONS
  We established a reproducible methodology for performing tractography of the tracts in question. FA and MD indexes may serve as early indicators of Alzheimer disease. The type of equipment and the method used to acquire images must be considered because they may alter results as shown by comparing the 2 data sets in this study.
authors.affiliation: Centro de Biomateriales e Ingeniería Tisular, Universitat Politècnica de València, Valencia, España.
authors.forename: A
authors.initials: A
authors.lastname: Larroza
authors.affiliation: Centro de Biomateriales e Ingeniería Tisular, Universitat Politècnica de València, Valencia, España. Electronic address: dmoratal@eln.upv.es.
authors.forename: D
authors.initials: D
authors.lastname: Moratal
authors.affiliation: Centro de Biomateriales e Ingeniería Tisular, Universitat Politècnica de València, Valencia, España.
authors.forename: V
authors.initials: V
authors.lastname: D'ocón Alcañiz
authors.affiliation: Servicio de Radiología, Fundación Instituto Valenciano de Oncología, Valencia, España.
authors.forename: E
authors.initials: E
authors.lastname: Arana
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology*; D016880:Anisotropy; D060825:Cognitive Dysfunction / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013702:Temporal Lobe / Q000473:pathology*
keywords: Alzheimer disease; Demencia; Dementia; Deterioro cognitivo leve; Diffusion-weighted imaging; Enfermedad de Alzheimer; Imagen potenciada en difusión; Mild cognitive impairment; Sustancia blanca; Tractografía; Tractography; White matter