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Diffusion anisotropy in excised normal rat spinal cord measured by NMR microscopy
B A Inglis1, L Yang, E D Wirth
1Department of Biochemistry and Molecular Biology, University of Florida, Gainesville 32610, USA.
Magnetic Resonance Imaging
|January 1, 1997
Summary
High-resolution magnetic resonance imaging reveals microscopic structural organization in rat spinal cords. Apparent diffusion tensor imaging effectively maps fiber orientations using diffusion anisotropy, providing a pseudo-3D view.
Area of Science:
- Neuroimaging
- Biophysics
- Magnetic Resonance Imaging
Background:
- Conventional spin-echo NMR imaging provides high-resolution images.
- High-resolution imaging necessitates large pulsed-field gradients, inducing significant diffusion weighting.
- This diffusion weighting can reveal microscopic structural organization beyond image matrix resolution.
Purpose of the Study:
- To measure anisotropic diffusion coefficients using apparent diffusion tensor (ADT) imaging.
- To accurately assess fiber orientations in the rat spinal cord.
- To develop a novel visualization method for diffusion anisotropy.
Main Methods:
- Utilized a conventional spin-echo NMR imaging pulse sequence at 7 and 14 T.
- Acquired high-resolution images of excised normal rat spinal cord.
- Applied apparent diffusion tensor (ADT) imaging to measure diffusion anisotropy.
- Generated a colored trace image from ADT diagonal elements for enhanced visualization.
Main Results:
- Observed that diffusion weighting dominated image contrast, enabling inference of microscopic structural organization.
- Demonstrated that ADT imaging accurately assesses fiber orientations.
- Introduced a colored trace image that retains trace invariance while displaying diffusion anisotropy.
- The colored trace image provides a pseudo-3D view for deducing fiber orientations.
Conclusions:
- Diffusion anisotropy measured by ADT imaging is a powerful tool for characterizing spinal cord microstructure.
- The novel colored trace image effectively visualizes diffusion anisotropy and fiber orientations.
- This approach offers enhanced insights into the structural organization of nervous tissue beyond conventional resolution limits.