The spread of a substance in a fluid from an area of high concentration to one of lower concentration.
a variant of *diffusion weighted imaging in which both the direction and the amount of diffusion of water molecules in a tissue are coded in the image. This MRI technique can be valuable in linear structures, such as nerves and muscle fibres. In the brain the major tracts and their communications can be studied with this technique (see tractography).... diffusion tensor imaging
a method of creating images by *magnetic resonance imaging that relies on the amount of available space that individual water molecules have to move in, which depends on the local microstructure. Pathological tissues generally are less organized, with more space for diffusion and a higher signal.... diffusion weighted imaging
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