Intervertebral disk degeneration - MRI classification by Watanabe et al.

In 2007, Watanabe et al. published grading of degenerative changes of the intervertebral disc by MRI. It is based on T2 weighted axial sections.

Grade T2 signal intensity (SI) of nucleus pulposus T2 signal intensity (SI) of anulus fibrosus Distinction of nucleus pulposus and anulus fibrosus
Grade I
  • high SI
  • homogeneous
  • low SI
  • homogeneous
clear with regular borders
Grade II
  • mildly decreased SI
  • mildly inhomogeneous
  • mildly increased SI
  • mildly inhomogeneous
clear with irregular borders
Grade III
  • moderately decreased SI
  • moderately inhomogeneous
  • moderately increased SI
  • moderately inhomogeneous
Grade IV
  • severely decreased SI
  • severely inhomogeneous
  • severely increased SI
  • severely inhomogeneous


1. Watanabe A, Benneker LM, Boesch C, Watanabe T, Obata T, Anderson SE. Classification of intervertebral disk degeneration with axial T2 mapping. AJR Am J Roentgenol. 2007 Oct;189(4):936–42.