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Reliability of MRI Readings in Lumbar Stenosis
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Appendix 1. Quantitative Measurement Definitions.
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Osseos Canal Length – (Figure 1a) The anterior-posterior length of the spinal canal in
millimeters from the posterior edge of the intervertebral disc space (estimated location of the
endplate) to the most posterior point of the bony canal in the axial plane (MEASUREMENT A).
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Soft Tissue Canal Length – (Figure 1b) The anterior-posterior length of the spinal canal in
millimeters from the posterior edge of the disc margin to the most posterior ligamentous edge in
the axial plane (MEASUREMENT C).
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Osseos Canal Width – (Figure 1a) The left –right width of the bony canal in millimeters
measured at the midpoint of the line which defines the canal length (MEASUREMENT B).
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Soft Tissue Canal Width – (Figure 1b) The left –right width of the spinal canal in millimeters
measured at the midpoint of the line which defines the canal length with the lateral borders
formed by the medial edges of the ligaments(MEASUREMENT D).
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Figure 1a
Figure 1b
A
B
C
D
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Reliability of MRI Readings in Lumbar Stenosis
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Osseos Canal Area – (Figure 2a) The cross-sectional area in the axial plane, measured in square
millimeters, of the bony canal at the level of the disc. Margins are the posterior edge of the
intervertebral disc space (estimated location of the endplate) and the bony structures laterally and
posteriorly. The area will be extended perpendicularly from the facet joint edges to the disc
space across those areas where the lateral margin is absent.
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ST Canal Area – (Figure 2b) The cross-sectional area in the axial plane, measured in square
millimeters, of the spinal canal at the level of the disc. Margins are the posterior edge of the disc
margin and the ligamentous structures laterally and posteriorly. The area will be extended
perpendicularly from the ligament overlying the facet joint edges to the disc space across those
areas where the lateral margin is absent.
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Figure 2a
Figure 2b
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Reliability of MRI Readings in Lumbar Stenosis
Figure 3
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Thecal sac area – (Figure 3) The cross-sectional
area in the axial plane, measured in square
millimeters, of the thecal sac on T2 weighted
images.
Canal and thecal sac area measures to be
made on the T2 Axial images at level of the
disc.
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