We have related the diagonal and off-diagonal elements of the effective self-diffusion tensor, D, to the echo intensity in NMR spin-echo experiments. Using this expression, we have designed pulse sequences from which we can estimate D using a series of diffusion-weighted images. This estimate is validated using isotropic and anisotropic media. One application of this work is to use D to determine fiber orientation noninvasively in vivo. Moreover, we can infer mean diffusion distances and tissue microstructure within a voxel. We also have developed a new MR imaging modality: Diffusion Tensor MRI, in which we use D to construct images of diffusion ellipsoids that depict the local fiber orientation and mean diffusion distances, as well as images of the three scalar invariants of D that are independent of the reference frame in which magnetic field gradients and D are measured, and to provide new information about tissue microstructure and physiology. Clinical applications are anticipated in stroke monitoring and tumor diagnosis.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Intramural Research (Z01)
Project #
1Z01RR010398-03
Application #
3767471
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
3
Fiscal Year
1994
Total Cost
Indirect Cost
Name
National Center for Research Resources
Department
Type
DUNS #
City
State
Country
United States
Zip Code