The D values primarily reflect overall brain water content. The A sigma values are more sensitive to tissue microstructure (e.g., white matter packing and myelination). The D and A sigma images reveal information and not apparent on T1- and T2-weighted images.

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The equilibrium shapes of long chain polymers in a dilute solution in good solvent are investigated Rotationally invariant quantities Δ and S which characterize the average asymmetry and degree of prolate — or oblateness of a polymer configuration are defined These amplitude ratios are proved to be universal, and calculated to first order in an ε = 4 - d expansion. The polymers are shown to be on average quite asymmetric and prolate

Quantitative diffusion anisotropy images can be obtained rapidly and demonstrate subtle WM anatomy. Different histologic types of WM have significant and reproducible anisotropy differences.

No abstract