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. Author manuscript; available in PMC: 2015 Jun 26.
Published in final edited form as: Handb Clin Neurol. 2012;109:85–101. doi: 10.1016/B978-0-444-52137-8.00006-1

Figure 4.

Figure 4

Demonstration of q-space derived values of root mean square displacement (RMSD) and PDF height (P0) in a healthy volunteer compared to a patient with MS. In the left panel, the q-space derived single voxel PDFs are shown for each of the voxels shown on the images. In normal white matter, it can be seen that a “healthy” PDF is tall and narrow (yellow and blue) while in gray matter (red) the PDF is low and broad. In the MS case with a prevalent lateral column lesion, the PDF for a voxel in the lesion (yellow) approximates the PDF for gray matter (red), while the uninjured column (dorsal column – blue) appears tall and narrow. For the derived RMSD and P0 maps, note that a high RMSD indicates a broader PDF while a high P0 indicates a tall PDF. Figure modified from Farrell JAD, et al, MRM 2008.