Volume 8, Issue 7 p. 333-344
Articles

Inferring microstructural features and the physiological state of tissues from diffusion-weighted images

Peter J. Basser

Corresponding Author

Peter J. Basser

Biomedical Engineering and Instrumentation Program, NCRR, National Institutes of Health, Building 13, Room 3N-17, 13 South Drive, Bethesda, MD 20892-5766, USA

Biomedical Engineering and Instrumentation Program, NCRR, National Institutes of Health, Building 13, Room 3N-17, 13 South Drive, Bethesda, MD 20892-5766, USASearch for more papers by this author
First published: November/December 1995
Citations: 1,167

Abstract

We review several methods that have been developed to infer microstructural and physiological information about isotropic and anisotropic tissues from diffusion weighted images (DWIs). These include Diffusion Imaging (DI), Diffusion Tensor Imaging (DTI), isotropically weighted imaging, and q-space imaging. Just as DI provides useful information about molecular displacements in one dimension with which to characterize diffusion in isotropic tissues, DTI provides information about molecular displacements in three dimensions needed to characterize diffusion is anisotropic tissues. DTI also furnishes scalar parameters that behave like quantitative histological or physiological‘stains’ for different features of diffusion. These include Trace(D), which is related to the mean diffusivity, and a family of parameters derived from the diffusion tensor, D, which characterize different features of anisotropic diffusion. Simple thought experiments and geometrical constructs, such as the diffusion ellipsoid, can be used to understand water diffusion in isotropic and anisotropic media, and the NMR experiments used to characterize it.