Intraobserver agreement among the three readers based on 40 MRI’s.

Reader A en B represent the two neuroradiologists, while reader C represents the neurosurgeon.
*Since kappa values are afected by the prevalence of events, kappa values were only calculated for findings reported in more than 10% and less than 90% of all reports.
¶The 5 categories were: 1) L2L3 2) L3L4 3) L4L5 4) L5S1 5) Not applicable, all disc levels have a normal disc contour: no disc extension beyond the normal margins of the intervertebral disc space.
∫The 4 categories were: 1) Definite about the presence 2) Probable about the presence 3) Possible about the presence 4) Definite about the absence.
‡The categories “Definite and probable about the presence” were combined and the categories “possible about the presence” and “definite about the absence” were combined to one category.
∥Categories were: bulging disc versus disc herniation.
§Categories were: yes versus no.
ΨCategories were: 1) Hypointensity 2) Normal 3) Hyperintensity.
|--Categories were: 1) No vertebral endplate signal changes (VESC) 2) VESC type I 3) VESC type II.
4) VESC type III 5) Mixed VESC type I/II 6) Mixed VESC type II/III.
⊢Categories were: 1) Yes, completely disappeared 2) Yes, partly disappeared 3) No disappearance.
ζCategories were: 1) Sub-articular zone 2) Foraminal zone 3) Extra-foraminal zone.
∥–Categories were: 1) Normal 2) Thickened 3) Narrowed.
ΩCategories were: 1) Central zone 2) Sub-articular zone 3) Foraminal zone 4) Extra-foraminal zone.
ΘCategories were: 1) Disc level 2) Folded upwards 3) Folded downwards.
ŸCategories were: 1) Large stenosing: size >75% of the spinal canal 2) Large: size 50–75% of the spinal canal 3) Average: size 25–50% of the spinal canal and 4) Small: size <25% of the spinal canal.
χThe categories “large stenosing” and “large” were combined to one category and the categories “average” and “small” were also combined to one category.