Intraobserver agreement
| Variable | Intraobserver Agreement CTFa | Intraobserver Agreement Nordica |
|---|---|---|
| Intravertebral herniation | 0.682 (0.389; 0.835) | 0.694 (0.530; 0.852) |
| Disk contour at L1-L2, L2-L3, and L3-L4b | 0.750 (0.654; 0.824) | 0.714 (0.608; 0.776) |
| Disk contour at L4-L5 and L5-S1 | ||
| Considering bulging as abnormalb | 0.728 (0.622; 0.864) | 0.642 (0.558; 0.816) |
| Considering bulging as normalc | 0.624 (0.538; 0.667) | 0.565 (0.460; 0.717) |
a Mean (5th percentile, 95th percentile) of κ values. Agreement is classified as almost perfect (κ value > 0.81), substantial (0.61–0.80), moderate (0.41–0.60), fair (0.21–0.40), slight (0.00–0.20), or poor (<0.00).
b Agreement in classifying images in the 2 following categories: normal vs bulging + focal protrusion + broad-based protrusion + extrusion, according to the CTF nomenclature; or normal vs symmetric bulging + protrusion (focal or broad-based) + hernia (extrusion or sequestration), according to the Nordic nomenclature.
c Agreement in classifying images in the 2 following categories: normal + bulging vs focal protrusion + broad-based protrusion + extrusion, according to the CTF nomenclature; or normal + symmetric bulging vs protrusion (focal or broad-based) + hernia (extrusion or sequestration), according to the Nordic nomenclature.