Review Article
The basis of anisotropic water diffusion in the nervous system – a technical review
Article first published online: 5 DEC 2002
DOI: 10.1002/nbm.782
Copyright © 2002 John Wiley & Sons, Ltd.
Issue
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NMR in Biomedicine
Special Issue: Diffusion tensor imaging and axonal mapping - state of the art
Volume 15, Issue 7-8, pages 435–455, November - December 2002
Additional Information
How to Cite
Beaulieu, C. (2002), The basis of anisotropic water diffusion in the nervous system – a technical review. NMR Biomed., 15: 435–455. doi: 10.1002/nbm.782
Publication History
- Issue published online: 5 DEC 2002
- Article first published online: 5 DEC 2002
- Manuscript Accepted: 16 OCT 2001
- Manuscript Revised: 12 OCT 2001
- Manuscript Received: 5 JUN 2001
Funded by
- Alberta Heritage Foundation for Medical Research
- Canadian Institutes of Health Research
- Abstract
- Article
- References
- Cited By
Keywords:
- diffusion;
- anisotropy;
- nerve;
- white matter;
- spinal cord;
- water;
- MRI;
- DTI
Abstract
Anisotropic water diffusion in neural fibres such as nerve, white matter in spinal cord, or white matter in brain forms the basis for the utilization of diffusion tensor imaging (DTI) to track fibre pathways. The fact that water diffusion is sensitive to the underlying tissue microstructure provides a unique method of assessing the orientation and integrity of these neural fibres, which may be useful in assessing a number of neurological disorders. The purpose of this review is to characterize the relationship of nuclear magnetic resonance measurements of water diffusion and its anisotropy (i.e. directional dependence) with the underlying microstructure of neural fibres. The emphasis of the review will be on model neurological systems both in vitro and in vivo. A systematic discussion of the possible sources of anisotropy and their evaluation will be presented followed by an overview of various studies of restricted diffusion and compartmentation as they relate to anisotropy. Pertinent pathological models, developmental studies and theoretical analyses provide further insight into the basis of anisotropic diffusion and its potential utility in the nervous system. Copyright © 2002 John Wiley & Sons, Ltd.
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- ADC
apparent diffusion coefficient
- b
gradient factor
- D
diffusion coefficient
- DTI
diffusion-tensor imaging
- DWI
diffusion-weighted imaging
- EAE
experimental allergic encephalomyelitis
- G
strength of diffusion gradients
- PGSE
pulsed-gradient spin-echo
- RMS
root mean square displacement
- SNR
signal-to-noise ratio
- T2
transverse relaxation time
- tdif
diffusion time
- TE
spin-echo time
- ∥
parallel to the fibre's long axis
- ⟂
perpendicular to the fibre's long axis
- δ
length of diffusion gradient
- Δ
onset separation of diffusion gradients
- λ
principal eigenvalues

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