Table 3:

Number of images classified by each radiologist as normal or abnormal using both nomenclatures and depending on whether bulging was considered to be normal or abnormal (levels L4-L5 and L5-S1)

	CTF								Nordic
	Control 1				Control 2				Control 1				Control 2
	Considering Bulging Abnormal^a		Considering Bulging Normal^b		Considering Bulging Abnormal^a		Considering Bulging Normal^b		Considering Bulging Abnormal^a		Considering Bulging Normal^b		Considering Bulging Abnormal^a		Considering Bulging Normal^b
	N	A	N	A	N	A	N	A	N	A	N	A	N	A	N	A
L4-L5
Rx1	5	48	32	21	2	51	30	23	11	42	32	21	13	40	32	21
Rx2	5	48	48	5	3	50	43	10	9	44	49	4	9	44	49	4
Rx3	13	40	37	16	14	39	43	10	21	32	42	11	25	28	39	14
Rx4	23	30	47	6	19	34	44	9	21	32	48	5	29	24	46	7
Rx5	18	35	36	17	22	31	36	17	22	31	50	3	23	30	52	1
L5-S1
Rx1	24	29	34	19	20	33	33	20	21	32	29	24	23	30	34	19
Rx2	16	37	42	11	11	42	46	7	11	42	49	4	18	35	50	3
Rx3	20	33	30	23	22	31	39	14	20	33	37	16	25	28	33	20
Rx4	28	25	44	9	24	29	40	13	28	25	43	10	35	18	44	9
Rx5	24	29	34	19	25	28	33	20	24	29	44	9	26	27	48	5

a 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.
b 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.