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AJNR - American Journal of Neuroradiology

Published ahead of print on June 4, 2008
doi: 10.3174/ajnr.A1154

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Attenuation of Lower-Thoracic, Lumbar, and Sacral Spinal Cord Motion: Implications for Imaging Human Spinal Cord Structure and Function

C.R. Figley^a, D. Yau^a,b and P.W. Stroman^a,c,d

^a Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
^b Faculty of Health Science, Queen's University, Kingston, Ontario, Canada
^c Department of Diagnostic Radiology, Queen's University, Kingston, Ontario, Canada
^d Department of Physics, Queen's University, Kingston, Ontario, Canada

View larger version (102K): [in this window] [in a new window]   Fig 1. To characterize A/P spinal cord motion, midsagittal CINE images were acquired at 24 phases of the cardiac cycle. To span the length of the cord, 2 sets of overlapping data were acquired. A, Spanning the lower-cervical and upper-thoracic vertebral levels. B, Spanning the lower-thoracic and upper-lumbar vertebral levels (below the level of the conus medullaris). These sections were positioned such that there was approximately one vertebral level of overlap (denoted by the 2 horizontal white lines) between the rostral and caudal datasets, thus enabling uninterrupted characterization of motion along the cord.

View larger version (15K): [in this window] [in a new window]   Fig 2. The peak A/P spinal cord displacement averaged across all of the subjects and plotted as a function of R/C cord position (ie, vertebral level). The black line indicates the cross-subject average of peak displacement, whereas the gray area indicates the region within 1 SD of the mean at each R/C position. Motion below the level of midthoracic vertebrae (around T4 or T5) is significantly lower compared with more rostral cord regions.

View larger version (53K): [in this window] [in a new window]   Fig 3. Cardiac-related A/P motion data from a typical subject exhibiting motion of this type. Spinal cord displacement is indicated as a function of cardiac phase and R/C cord position (ie, vertebral level). Positive displacement values indicate anterior motion, whereas negative values indicate posterior motion. Clearly, cord displacements are maximal midway through the cardiac cycle and only at the level of upper-thoracic vertebrae. Conversely, motion dies off and is minimal (at any cardiac phase) at the level of mid- to lower-thoracic vertebrae. This pattern of decreasing motion along the cord, and quiescence in caudal regions, was also evident in other test subjects.

View larger version (16K): [in this window] [in a new window]   Fig 4. The peak L/R spinal cord displacement averaged across all of the subjects and plotted as a function of R/C cord position (ie, vertebral level). The black line indicates the cross-subject average of peak displacement, whereas the gray area indicates the region within 1 SD of the mean at each R/C position. To facilitate comparisons between cord motions in each direction (A/P and L/R), the scale has been normalized to that shown for the larger A/P displacements (plotted in Fig 2). Note, however, that the average peak displacement is not significantly larger than 0.10 mm (the estimated measurement precision) at any R/C position, except at the level of T6.