Table 1.

Classification of intervertebral disk degeneration on MRI (Pfirrman scale)

Grades	Structures	Distinction between nucleus and annulus	Signal intensity	Disk height
I	Bright white, homogeneous	Clear	Hyperintense, isointense to cerebrospinal fluid	Normal
II	Inhomogeneous with or without horizontal bands	Clear	Hyperintense, isointense to cerebrospinal fluid	Normal
III	Gray, inhomogeneous	Unclear	Intermediate	Normal to slightly decreased
IV	Gray to black, inhomogeneous	Lost	Intermediate to hypointense	Normal to moderately decreased
V	Black, inhomogeneous	Lost	Hypointense	Collapsed