Correlation Analysis between Tamoxifen and Lumbar Intervertebral Disc Degeneration: A Retrospective Case-Control Study

Table 1

Modified Pfirrmann grading system.

	Strength of nucleus pulposus and inner annulus fibrosus	Signal difference between the inner and outer sides of the posterior annulus fibrosus	Intervertebral disc height
Grade 1	Homogeneous high signal, equivalent to cerebrospinal fluid (CSF)	Obvious	Normal
Grade 2	High signal, lower than CSF, higher than presacral fat	Obvious	Normal
Grade 3	High signal, lower than presacral fat	Obvious	Normal
Grade 4	Moderate signal, higher than the outer annulus fibrosus	Not obvious	Normal
Grade 5	Low signal, equivalent to low outer annulus fibrosus	Not obvious	Normal
Grade 6	Low signal	Not obvious	Reduced less than 30%
Grade 7	Low signal	Not obvious	Reduced 30%–60%
Grade 8	Low signal	Not obvious	Reduced more than 60%