HMB310H1 Lecture Notes - Lecture 8: Diffusion Mri, White Matter, Myelin
Document Summary
Tissue characterized: t1 and t2 are different kinds of contrasts, t1 is best for visualizing brain csf is dark, t2 csf is bright (grey/white matters are darkened) Change in vasculature, oxygen in blood system meaning tumor **: myelin is also full of water so it is a little different for t2. Just different sequences: anatomic vs metabolic function (respectively, hydrogen activity vs oxygen level (respectively, both need the structural information. Diffusion tensor imaging: we look at white matter structures, we don"t use it diagnostically but understanding tracts, etc, tumor removal repair observations, characterizes water diffusion within tissue. Isotropic diffuses freely in any direction like csf. In the ventricles: anisotropic restricted in direction of diffusion (one direction more than other) Pathways: healthy white matter **, we assign values to the randomness or lack of randomness which are compared to, define pathways (tractopgraphy) Qualities of white matter pathways how intact is the pathway. Use fractional anisotropy (fa) which measures degree of anisotropy.
