title: Diffusion anisotropy color-coded map of cerebral white matter: quantitative comparison between orthogonal anisotropic diffusion-weighted imaging and diffusion tensor imaging.
abstract: OBJECTIVE
  Diffusion anisotropy color-coded maps of cerebral white matter can be generated from orthogonal anisotropic diffusion-weighted imaging (DWI) using the three-dimensional anisotropy contrast (3DAC) technique, but its precision has not been fully validated. Hence, we attempted to determine whether 3DAC is comparable to a diffusion tensor imaging (DTI) color map.
  
  
  METHODS
  We examined 15 healthy individuals and generated color-coded maps using 3DAC as well as using primary eigenvector (e1) and fractional anisotropy (FA) from identical DTI datasets. The difference in the direction of the 3DAC vector from e1 (θ) in cerebral white matter was evaluated. Correlations between θ and FA or obliqueness of e1 were also examined.
  
  
  RESULTS
  In cerebral white matter, θ had significantly negative and positive correlations with FA values and e1 obliqueness, respectively. Among white matter tracts, the pyramidal tract, cingulum, and corpus callosum, which had significantly high FA and/or low obliqueness, exhibited similar coloration and significantly smaller θ (4.4° ± 1.6°, 9.3° ± 2.8°, and 11.2° ± 1.1°, respectively) than the entire white matter (13.9° ± 1.1°).
  
  
  CONCLUSIONS
  The 3DAC could visualize directional information of white matter tracts as precisely DTI-based color maps did, particularly when FA was large and/or e1 directions were orthogonal.
authors.affiliation: Division of Ultra-High Field, Institute for Biomedical Sciences, Iwate Medical University, Uchimaru, Morioka, Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Uwano
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
authors.forename: Shunrou
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Mao
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Ayumi
authors.initials: A
authors.lastname: Saito
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.forename: Akira
authors.initials: A
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D016880:Anisotropy; D003116:Color; D003124:Colorimetry / Q000379:methods; D003196:Computer Graphics; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity