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Two‐step anomalous diffusion tensor imaging
Author(s) -
Hall Matt G.,
Barrick Thomas R.
Publication year - 2012
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1747
Subject(s) - diffusion mri , anisotropy , fractional anisotropy , tensor (intrinsic definition) , exponent , white matter , physics , anomalous diffusion , diffusion , eigenvalues and eigenvectors , nuclear magnetic resonance , mathematical analysis , mathematics , geometry , optics , magnetic resonance imaging , quantum mechanics , computer science , medicine , linguistics , philosophy , innovation diffusion , knowledge management , radiology
We extend the formalism of anomalous diffusion imaging to include directional anisotropy of fitted parameters. The resulting technique is termed anomalous diffusion tensor imaging (aDTI), and allows the directional properties of the distributed diffusion coefficient ( α ) and the anomalous diffusion exponent, ( γ ) to be analysed using the same analytical techniques as regular diffusion tensor imaging (DTI). Together, these parameters quantify the rate of diffusion ( α ) and the complexity of the diffusion environment ( γ ). We generated tensor images for the anomalous exponent tensor (Γ) and distributed diffusivity tensor ( A ) from in vivo human brain data and present images of eigenvalues, eigenvectors, Trace/3 (Tr), fractional anisotropy (FA) and tensor shape measures. In white matter, A is found to have a median Tr = 0.56 × 10 − 3 mm 2 s − 1 , FA = 0.58 and Γ Tr = 0.69, FA = 0.13. We observed that white matter shows a similar anisotropic geometry for the distributed diffusion tensor as for the regular diffusion tensor, whereas the anomalous exponent tensor exhibits a different shape characteristic which may be informative of tissue microstructure. Copyright © 2011 John Wiley & Sons, Ltd.