Table 1.

Modified Dallas discogram scale

Grade	Morphology of CT discograms
0	Normal disc
1	Radial fissure involving the middle third of the annulus
2	Radial fissure extending to the middle third of the annulus
3	Radial fissure extending to the outer third of the annulus but involving < 30° of the disc circumference
4	Radial fissure extending to the outer third of the annulus and involving > 30° of the disc circumference