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AJNR - American Journal of Neuroradiology

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Diffusion-weighted MR Imaging of the Normal Human Spinal Cord in Vivo

Chad A. Holder^,a,b, Raja Muthupillai^a, Srinivasan Mukundan Jr^a, James D. Eastwood^a and Patricia A. Hudgins^a

^a From the Department of Radiology (C.A.H., S.M., J.D.E., P.A.H.), Emory University School of Medicine, Atlanta, GA and Philips Medical Systems North America (R.M.), Shelton CT.
^b Address reprint requests to Chad A. Holder, MD, Assistant Professor of Radiology, Emory University School of Medicine, Department of Radiology, Emory University Hospital/B115, 1364 Clifton Rd, NE, Atlanta, GA 30322.

View larger version (20K): [in a new window]   FIG 1. Navigator-corrected, multi-shot, spin-echo echo-planar pulse sequence with diffusion-sensitizing gradients of amplitude (G), duration (), and separation (). The diffusion gradients can be applied along any imaging direction. The navigator echo (the first spin-echo of this dual echo sequence) is not spatially encoded, and is used for phase correction of the second echo

View larger version (149K): [in a new window]   FIG 2. Axial diffusion-weighted images (2 R-R/106/4 [TR/TE/excitations]) showing the appearance of the cervical spinal cord with the diffusion-probing gradients in the three cardinal axes, with increasing b values from left to right. R-L, A-P, and C-C indicate the direction of the diffusion gradients. The R-L and A-P directions are perpendicular to the white matter tracts. The C-C direction is parallel to the white matter tracts. Note the relatively greater signal attenuation with the diffusion gradients in the C-C direction, reflecting the underlying tissue anisotropy. Note also the reversal of the relative signal intensity of gray and white matter at the higher b values (640, 1000) in the C-C direction, due to the higher ADC of white matter along this axis

View larger version (89K): [in a new window]   FIG 3. Sagittal diffusion-weighted images (2 R-R/106/4) showing the appearance of the cervical spinal cord with the diffusion-probing gradients in the three cardinal axes, with increasing b values from left to right. The R-L and A-P directions are perpendicular to the white matter tracts. The C-C direction is parallel to the white matter tracts. Again, there is relatively greater signal attenuation with the diffusion gradients in the C-C direction. Note the sensitivity of the diffusion-weighted sequence to pulsation at the highest b value in the A-P diffusion direction, resulting in artifact in the phase-encoding direction