'Proteoglycan Profiling' of lumbar disc displacement in humans: novel imaging biomarkers utilising T1rho magnetic resonance imaging

Abstract

BACKGROUND: Lumbar disc displacement can lead to low back pain. It is believed that disc displacement is degenerative in origin, but controversy exists. Novel T1rho magnetic resonance imaging (MRI) is more sensitive than traditional T2-weighted MRI for assessing disc degeneration via quantifying loss of proteoglycan in disc. Hence, by utilising T1rho MRI, we addressed the ‘proteoglycan profile’ for each lumbar disc and level-specific threshold values as biomarkers for disc displacement. METHODS: This was a cross-sectional MRI study of 76 volunteers (380 discs; mean age 50.6 years and 51.3% male) who underwent T2-weighted and T1rho MRIs assessing the lumbar spine (L1-S1). Receiver operative characteristic curves were used to assess diagnostic T1rho values associated with disc displacement for each lumbar disc. RESULTS: Of all the discs, 50% had disc displacement, and the mean T1rho value for non-displaced discs was 77.6 ms compared with 64.5 ms for displaced discs. Optimal cutoff T1rho values for each lumbar disc level had been obtained as potential biomarkers for lumbar disc displacement. CONCLUSION: This is the first study in humans to quantitatively assess ‘proteoglycan profile’ of disc displacement throughout the lumbar spine. Based on T1rho MRI, our group has identified a decrease in proteoglycan concentration in the presence of disc displacement at all levels. Level-specific values have been identified that may have predictive utility at the index or adjacent levels, which may aid in classification, aetiology, natural history, and therapeutics of disc displacement.