Table 1 Classification of MRI findings

Spondylolisthesis, (Meyerding [27])

Ordinal

Defined as slippage of the vertebral body in relation to the one below in: Anterior, posterior or lateral direction.

0

Normal

 Grade I

1

Displacement of vertebral body ≤ ¼ of vertebral body below.

 Grade II

2

Displacement of vertebral body ≤ ½ of vertebral body below.

 Grade III

3

Displacement of vertebral body ≤ ¾ of vertebral body below.

 Grade IV

4

Displacement of vertebral body ≤ 4/4 of vertebral body below.

Disc degeneration, (Pfirrmann [22])

Ordinal

For this study grade I and II is considered normal.

 Grade I:

0

Nucleus pulposus is homogenous and has high, bright white, signal intensity. Clear distinction of nucleus and annulus. Normal heights of the intervertebral disk

 Grade II:

0

Like grade I, but the nucleus pulposus is inhomogeneous, with or without clear horizontal bands.

 Grade III:

1

Nucleus pulposus being inhomogeneous and gray, unclear distinction of the nucleus and annulus, intermediate signal intensity and normal to slightly decreased intervertebral disc height.

 Grade IV:

2

Inhomogeneous, gray to black nucleus pulposus and no distinction between the nucleus and the annulus. The signal intensity is intermediate to hypointense and normal to moderately decreased disc height.

 Grade V:

3

Nucleus pulposus is inhomogeneous and black, with hypointense signal intensity and collapsed disk space.

Nerve root compromise, (Lee [24])

Ordinal

 Normal

0

No contact to nerve roots

 Contact

1

Perineural fat obliteration from two opposing sides. No morphologic change (no signs of compression/deformation) of the nerve root.

 Contact and deviation

2

Perineural fat obliteration surrounding the nerve root from four sides. No morphologic change (no compression/deformation) of nerve root.

 Compression

3

Visible nerve root collapse or morphologic change

Spinal stenosis, (Lee [24])

Ordinal

  No stenosis:

0

Up to 3 mm disc bulge is normal.

  Relative stenosis:

1

Reduced space < 50%, but still visible fluid signal around the nerve roots.

  Absolute stenosis:

2

50% reduction or more of the dural sac area and no visible signal (dark/black) from cerebrospinal fluid around the nerve roots or medulla spinalis.

  No stenosis:

0

Normal levels of perineural fat.

  Relative stenosis:

1

Reduced space, perineural fat obliteration from at least two opposing sides but still visible perineural fat/CSF signal in the recess.

  Absolute stenosis:

2

Reduction of the recess to a point where perineural fat signal/CSF signal no longer is visible.

  No stenosis:

0

Normal upside-down pear shape contour of the foramina with an apical nerve root location.

  Relative stenosis:

1

Reduced space, but still visible perineural fat signal in the foramen.

  Absolute stenosis:

2

Reduction of the foramen to the point where perineural fat signal is no longer visible.

 (Ross/Moore [30]; Pathria [31])

Ordinal

  No degeneration:

0

Normal

  Mild degeneration:

1

Mild joint space narrowing and joint irregularity.

  Moderate degeneration:

2

Moderate joint space narrowing/irregularity, subchondral sclerosis/osteophyte formation.

  Severe degeneration:

3

Little, if any, joint space, severe subchondral sclerosis/ osteophyte formation. Possible subluxation and/or subchondral cyst formation.

 Scoliosis (Cobb [29])

Binominal

Defined as any spinal curvature with a Cobb’s angle greater than 10 degrees.

  sinistro convex

0/1

Apex of the curvature to the left.

  dextro convex

0/1

Apex of the curvature to the right.

  rotational

0/1

Pedicles and spinous process oriented to the left or right.

 Annular Fissure, (April [23])

Binominal

0/1

High T2 signal (HIZ) in the otherwise low signal annulus. Diameter > 1.5 mm. Annulus material visible all around the fissure.

 Disc contour, (Fardon [32])

Nominal

  Normal or bulge

0

< 3 mm and > 25% of the disc periphery (90 degrees). Negative for herniation.

  Protrusion:

1

< 25% (90 degrees) of disc periphery, distance between disco-vertebral corners is greater than distance of disc material past the base, measured in same plane.

  Extrusion:

2

Dimension of disc material in any one direction is greater than distance between disco-vertebral corners. Migration cephalad or caudad indicates extrusion.

  Sequestration:

3

Disc material has lost continuity with the parent disc.

  Combination of types

4

Combined protrusion and extrusion