Spinal Cord Measurement Protocol
Imaging sequences consist of sagittal and axial T1-weighted images (TR
500-650/TE 15), sagittal turbo spin-echo T2-weighted images. A specialized
set of axial turbo spin-echo T2-weighted (TR 4000/TE (eff) 120) images,
using a 256 x 256 matrix with a 22 cm field of view, are obtained in planes
that are perpendicular to the spinal cord, approximated by visual inspection.
Single axial images are obtained at each disk space level from C2/3 through
C7/T1 with a slice thickness of 4 mm. Axial images are also obtained at
the level of the base of the odontoid and the foramen magnum, perpendicular
to the upper spinal cord, approximated by visual inspection (Figure 1).
The AP spinal cord, transverse spinal cord and spinal canal diameters
are measured on these specialized T2-weighted axial images using the MR
scanner software (Figure 2).
To avoid ambiguity and maximize reproducibility, all measures are indexed
to the canal level at the disc space, i.e., the C2-3 disc becomes the
C2 canal. Note that the spinal cord level is one level above the "canal
level." The AP compression ratio is computed from these last two
measures; cord area is calculated as the area of an ellipse (a = p/ 4