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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 27:2168-2178, November-December 2006
© 2006 American Society of Neuroradiology

BRAIN

Quantitative Characterization of the Corticospinal Tract at 3T

D.S. Reich^a,b, S.A. Smith^a,b,c,e, C.K. Jones^b,e, K.M. Zackowski^d,f, P.C. van Zijl^b,c,e, P.A. Calabresi^a and S. Mori^b,e

^a Department of Neurology, Johns Hopkins University, Baltimore, Md
^b Department of Radiology, Johns Hopkins University, Baltimore, Md
^c Department of Biophysics, Johns Hopkins University, Baltimore, Md
^d Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Md
^e F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD
^f Department of Physical Medicine and Rehabilitation, Kennedy Krieger Institute, Baltimore, MD

Please address correspondence to Daniel S. Reich, MD, PhD, 600 N Wolfe St, Pathology 509, Baltimore, MD 21287; e-mail: dreich2{at}jhmi.edu

BACKGROUND AND PURPOSE: White matter tract–specific imaging will probably become a major component of clinical neuroradiology. Fiber tracking with diffusion tensor imaging (DTI) is widely used, but variability is substantial. This article reports the ranges of MR imaging appearance and right-left asymmetry of healthy corticospinal tracts (CST) reconstructed with DTI.

METHODS: For 20 healthy volunteers, whole-brain DTI data were coregistered with maps of absolute T1 and T2 relaxation times and magnetization transfer ratio (MTR), all acquired at 3T. For each individual, the 2 reconstructed CSTs and their asymmetry were analyzed with respect to the number of fibers reconstructed; tract volume; and individual MR imaging parameters restricted to the tracts. Interscan variability was estimated by repeat imaging of 8 individuals.

RESULTS: Reconstructed fiber number and tract volume are highly variable, rendering them insensitive to abnormalities in disease. Individual tract-restricted MR imaging parameters are more constrained, and their population averages and normal ranges are reported. The average population asymmetry is generally zero; therefore, normal ranges for an index of asymmetry are reported. By way of example, CST-restricted MR imaging parameters and their asymmetries are shown to be abnormal in an individual with multiple sclerosis who had a lesion affecting the CST.

CONCLUSIONS: The results constitute a normative dataset for the following imaging parameters of the CST: T1, T2, MTR, fractional anisotropy, mean diffusivity, transverse diffusivity, and the 3 diffusion tensor eigenvalues. These data can be used to identify, characterize, and establish the significance of changes in diseases that affect the CST.

This article has been cited by other articles:

				D.S. Reich, K.M. Zackowski, E.M. Gordon-Lipkin, S.A. Smith, B.A. Chodkowski, G.R. Cutter, and P.A. Calabresi Corticospinal Tract Abnormalities Are Associated with Weakness in Multiple Sclerosis AJNR Am. J. Neuroradiol., February 1, 2008; 29(2): 333 - 339. [Abstract] [Full Text] [PDF]

				C. A. DeBoy, J. Zhang, S. Dike, I. Shats, M. Jones, D. S. Reich, S. Mori, T. Nguyen, B. Rothstein, R. H. Miller, et al. High resolution diffusion tensor imaging of axonal damage in focal inflammatory and demyelinating lesions in rat spinal cord Brain, August 1, 2007; 130(8): 2199 - 2210. [Abstract] [Full Text] [PDF]