Background
Objectives
Methods
Design
Sample size calculation
Study population and reliability sample
MRI-procedures
Raters, training and consensus
MRI evaluation and classification of findings
Diagnostic findings | Scale/categories | Definitions |
---|---|---|
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 | |
Central | ||
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. |
Lateral | ||
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. |
Foraminal | ||
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. |
Facet degeneration, | ||
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 |
Data management and statistical analysis
Characteristics | Cross-sectional study population (N = 230) | Reliability study sample Inter-rater analysis (n = 59) |
---|---|---|
Age, in years, mean | 42.1 (SD 12.1) | 38.1 (SD 14.1) |
Females, n(%) | 118 (51.1%) | 27 (45.8%) |
Patients, LBP, n(%) | 72 (31.3%) | 23 (39.0%) |
Patients, LBP + leg pain, n(%) | 96 (41.7%) | 12 (20.3%) |
Symptoms > 4 wks., n(%) | 168 (73.0%) | 35 (59.3%) |
No LBP persons, n(%) | 62 (27.0%) | 24 (40.7%) |
Results
Diagnostic finding N = 177 disc levels | Reliability Rater 1 vs. 2 | Reliability Rater 1 vs. 3 | Reliability Rater 2 vs. 3 | All | Landis and Koch scale |
---|---|---|---|---|---|
95% C.I. | 95% C.I. | 95% C.I. | Probabilistic benchmark | ||
Spondylolisthesis | |||||
Conger’s K | 0.24 [−0.16:0.64] | 0.36 [−0.01:0.72] | 0.36 [− 0.01:0.72] | 0.33 | Slight |
Gwet’s AC2 | 0.998 [0.997:1.000] | 0.998 [0.996:0.999] | 0.998 [0.996:0.999] | 0.99 | Almost perfect |
%-agreement | 0.998 [0.997:1.000] | 0.998 [0.996:0.999] | 0.998 [0.996:0.999] | 0.99 | Almost perfect |
Disc degeneration | |||||
Conger’s K | 0.60 [0.51:0.70] | 0.67 [0.58:0.76] | 0.76 [0.69:0.82] | 0.68 | Moderate |
Gwet’s AC2 | 0.90 [0.87:0.94] | 0.89 [0.85:0.93] | 0.91 [0.88:0.95] | 0.90 | Substantial |
%-agreement | 0.95 [0.93:0.96] | 0.94 [0.93:0.96] | 0.96 [0.95:0.97] | 0.95 | Substantial |
Nerve compromise | |||||
Conger’s K | 0.55 [0.38:0.71] | 0.56 [0.39:0.72] | 0.52 [0.34:0.70] | 0.54 | Fair |
Gwet’s AC2 | 0.96 [0.93:0.98] | 0.93 [0.90:0.96] | 0.92 [0.89:0.96] | 0.93 | Substantial |
%-agreement | 0.96 [0.95:0.98] | 0.95 [0.93–0.97] | 0.94 [0.92:0.97] | 0.95 | Substantial |
Spinal stenosis | |||||
Conger’s K | 0.19 [0.08:0.29] | 0.33 [0.22:0.45] | 0.43 [0.34:0.53] | 0.33 | Fair |
Gwet’s AC2 | 0.98 [0.97:0.98] | 0.98 [0.98:0.99] | 0.98 [0.97:0.98] | 0.98 | Almost perfect |
%-agreement | 0.98 [0.98:0.99] | 0.99 [0.98:0.99] | 0.98 [0.98:0.99] | 0.98 | Almost perfect |
Facet degeneration | |||||
Conger’s K | 0.27 [0.16:0.38] | 0.32 [0.21:0.42] | 0.35 [0.25:0.46] | 0.32 | Slight |
Gwet’s AC2 | 0.79 [0.74:0.84] | 0.79 [0.74:0.84] | 0.76 [0.71:0.82] | 0.78 | Moderate |
%-agreement | 0.88 [0.86:0.90] | 0.89 [0.86–0.91] | 0.87 [0.85:0.90] | 0.88 | Moderate |
Scoliosis | |||||
Cohen’s K | 0.49 [0.06:0.92] | 0.59 [0.22:0.96] | 0.75 [0.40:1.00] | 0.61 | Fair |
Gwet’s AC1 | 0.98 [0.96:1.00] | 0.98 [0.96:1.00] | 0.99 [0.97:1.00] | 0.98 | Almost perfect |
%-agreement | 0.98 [0.96:1.00] | 0.98 [0.96:1.00] | 0.99 [0.97:1.00] | 0.98 | Almost perfect |
Annular Fissure | |||||
Cohen’s K | 0.50 [0.32:0.68] | 0.45 [0.26:0.65] | 0.61 [0.45:0.77] | 0.53 | Moderate |
Gwet’s AC1 | 0.87 [0.82:0.93] | 0.88 [0.82:0.93] | 0.88 [0.83:0.93] | 0.88 | Almost perfect |
%-agreement | 0.88 [0.83:0.93] | 0.88 [0.83:0.93] | 0.89 [0.84:0.93] | 0.88 | Almost perfect |
Disc contour | |||||
Cohen’s K | 0.36 [0.25:0.48] | 0.27 [0.17:0.38] | 0.39 [0.29:0.49] | 0.34 | Fair |
Gwet’s AC1 | 0.73 [0.65:0.80] | 0.59 [0.50:0.68] | 0.62 [0.53:0.70] | 0.64 | Moderate |
%-agreement | 0.75 [0.69:0.82] | 0.64 [0.57:0.71] | 0.67 [0.60:0.74] | 0.69 | Substantial |