Degeneration alters the biochemical composition of the disc, affecting the mechanical integrity leading to spinal instability. Quantitative T2* MRI probes water mobility within the macromolecular network, a potentially more sensitive assessment of disc health. We determined the relationship between T2* relaxation time and proteoglycan content, collagen content, and compressive mechanics throughout the degenerative spectrum. Eighteen human cadaveric lumbar (L4-L5) discs were imaged using T2* MRI. The T2* relaxation time at five locations (nucleous pulposus or NP, anterior annulus fibrosis or AF, posterior AF, inner AF, and outer AF) was correlated with sulfated-glycosaminoglycan (s-GAG) content, hydroxyproline content, and residual stress and strain at each location. T2* relaxation times were significantly correlated with s-GAG contents in all test locations and were particularly strong in the NP (r-=-0.944; p-<-0.001) and inner AF (r-=-0.782; p-<-0.001). T2* relaxation times were also significantly correlated with both residual stresses and excised strains in the NP (r-=-0.857; p-<-0.001: r-=-0.816; p-<-0.001), inner AF (r-=-0.535; p-=-0.022: r-=-0.516; p-=-0.028), and outer AF (r-=-0.668; p-=-0.002: r-=-0.458; p-=-0.041). These strong correlations highlight T2* MRI's ability to predict the biochemical and mechanical health of the disc. T2* MRI assessment of disc health is a clinically viable tool showing promise as a biomarker for distinguishing degenerative changes.
- (T2 star)
- disc degeneration
- quantitative magnetic resonance imaging