Jonathan Andrew David Farrell1,2, Jiangyang Zhang2, Melina Jones3, Cynthia A. DeBoy3, Paul N. Hoffman3,4, Seth A. Smith1,2, Daniel S. Reich3,5, Peter A. Calabresi3, Peter C. van Zijl1,2
1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; 2Neuroscience Section, Division of MR Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 3Dept. of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 4Dept. of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 5Division of Neuroradiology, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
Dorsal root axotomy causes axonal degeneration with subsequent delayed myelin damage in the dorsal column. We investigated water diffusion perpendicular and parallel to the rat spinal cord (3 and 30 days post-injury). We compared contrasts from q-space analysis to conventional anisotropy and diffusivity measurements and histological staining for axonal and myelin damage. Perpendicular diffusion was increased, and more Gaussian in lesions compared to contralateral white matter, but was not specific for myelin damage. Parallel diffusion was decreased, and less Gaussian, which may be specific for axonal damage. Q-space contrasts, including kurtosis excess, provide a comprehensive assessment of white matter damage.
Keywords