Agreement among the readers.

A en B represent the two neuroradiologists, while C represents the neurosurgeon. Analysis with the total number of patients (n = 389). ¶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 at any lumbar disc level). ∫The 4 categories were: 1) “Definite about the presence” if there was no doubt about the presence. 2) “Probable about the presence” if there was some doubt but the probability was >50%. 3) “Possible about the presence” if there was reason to consider but the probability was <50%, and 4) “Definite about the absence” if there was no doubt about the absence. ‡The categories “Definite and probable about the presence” were combined to one category and the categories “possible about the presence” and “definite about the absence” were also combined to one category.