PT  - JOURNAL ARTICLE
AU  - Reich, D.S.
AU  - Smith, S.A.
AU  - Jones, C.K.
AU  - Zackowski, K.M.
AU  - van Zijl, P.C.
AU  - Calabresi, P.A.
AU  - Mori, S.
TI  - Quantitative Characterization of the Corticospinal Tract at 3T
DP  - 2006 Nov 01
TA  - American Journal of Neuroradiology
PG  - 2168--2178
VI  - 27
IP  - 10
4099  - http://www.ajnr.org/content/27/10/2168.short
4100  - http://www.ajnr.org/content/27/10/2168.full
SO  - Am. J. Neuroradiol.2006 Nov 01; 27
AB  - 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.