Grade Structure | Distinction of the nucleus and annulus | Signal intensity | Height of the intervertebral disk |
I: Homogeneous, bright white | Clear | Hyperintense, isointense to CSF | Normal |
II: Heterogeneous with or without horizontal bands | Clear | Hyperintense, isointense to CSF | Normal |
III: Heterogeneous, gray | Unclear | Intermediate | Normal to slightly decreased |
IV: Heterogeneous, gray or black | Lost | Intermediate or hypointense | Normal to moderately decreased |
V: Heterogeneous, black | Lost | Hypointense | Collapsed disk space |