Table 2

Classification of Disc Degeneration by Pfirrmann et al.

Grade	Structure and Anulus	Distinction of Nucleus	Signal Intensity Intervertebral Disc	Height of
I	Homogeneous, bright white	Clear	Hyperintense, isotense to cerebrospinal fluid	Normal
II	Inhomogeneous with or without horizontal bands	Clear	Hyperintense, isotense to cerebrospinal fluid	Normal
III	Inhomogeneous, gray	Unclear	Intermediate	Normal to slightly decreased
IV	Inhomogeneous, gray to black	Lost	Intermediate to hypointense	Normal to moderately decreased
V	Inhomogeneous, black	Lost	Hypointense	Collapsed disc space