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Novel diffusion anisotropy indices: An evaluation
Author(s) -
Wang JiunJie,
Chao Tsichian,
Wai YauYau,
Hsu YuanYu
Publication year - 2006
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20616
Subject(s) - contrast to noise ratio , anisotropy , diffusion mri , standard deviation , fractional anisotropy , noise (video) , sensitivity (control systems) , amplitude , diffusion , physics , nuclear magnetic resonance , mathematics , optics , statistics , medicine , computer science , image quality , thermodynamics , artificial intelligence , magnetic resonance imaging , electronic engineering , image (mathematics) , radiology , engineering
Purpose To systematically evaluate diffusion anisotropy (DA) using newly defined indices based on the diffusion deviation and mean diffusivity approach. Materials and Methods Measures of amplitude, area, and volume of the DA index (DAI) were measured and compared with regard to their sensitivity to changes in DA, susceptibility to noise in the original diffusion‐weighted (DW) images, and contrast‐to‐noise ratio (CNR) in homogenous regions. Simulations were performed under different levels of noise and DA. Human DTI data were acquired from eight normal volunteers. Results Indices of area and volume measures provided improved resolution for characterizing the DA compared to the eigenvalue ratio. The amplitude measure showed consistent performances with good CNR and less susceptibility to noise in the original data. Conclusion These indices are rotationally invariant without the requirement of eigenvalue sorting. At low anisotropy, all indices have a similar CNR. For larger DA, the first index (the deviation tensor divided by the DT) shows improved sensitivity, contrast‐to‐noise ratio (CNR), and noise immunity compared to the other indices. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.