Observation of microscopic diffusion anisotropy in the spinal cord using double-pulsed gradient spin echo MRI.
A double-pulsed gradient spin echo (d-PGSE) filtered MRI sequence is proposed to detect microscopic diffusion anisotropy in heterogeneous specimen. The technique was developed, in particular, to characterize local microscopic anisotropy in specimens that are macroscopically isotropic, such as gray matter. In such samples, diffusion tensor MRI (DTI) produces an isotropic or nearly isotropic diffusion tensor despite the fact that the medium may be anisotropic at a microscopic length scale. Using d-PGSE filtered MRI, microscopic anisotropy was observed in a "gray matter" phantom consisting of randomly oriented tubes filled with water, as well as in fixed pig spinal cord, within a range of b-values that can be readily achieved on clinical and small animal MR scanners. These findings suggest a potential use for this new contrast mechanism in clinical studies and biological research applications.
Komlosh
M E
ME
Section on Tissue Biophysics and Biomimetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-5772, USA. komloshm@yahoo.com
Lizak
M J
MJ
Horkay
F
F
Freidlin
R Z
RZ
Basser
P J
PJ
D000465:Algorithms; D000818:Animals; D016880:Anisotropy; D004058:Diffusion; D017352:Echo-Planar Imaging / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D013116:Spinal Cord / Q000166:cytology*; D013552:Swine
D013113:Spin Labels