Correlations between quantitative T2 and T1? MRI, mechanical properties and biochemical composition in a rabbit lumbar intervertebral disc degeneration model.

ABSTRACT: Improved diagnostic measures for intervertebral disc degeneration are necessary to facilitate early detection and treatment. The aim of this study was to correlate changes in mechanical and biochemical properties with the quantitative MRI parameters T2 and T1? in rabbit lumbar discs using an ex vivo chymopapain digestion model. Rabbit lumbar spinal motion segments from animals less than 6 months of age were injected with 100??l of saline (control) or chymopapain at 3, 15, or 100?U/ml (n?=?5 per group). T2 and T1? MRI series were obtained at 4.7T. Specimens were mechanically tested in tension-compression and creep. Normalized nucleus pulposus (NP) water and GAG contents were quantified. Stepwise multiple linear regression was performed to determine which parameters contributed significantly to changes in NP T2 and T1?. When all groups were included, multiple regression yielded a model with GAG, compressive modulus, and the creep time constants as variables significantly impacting T2 (multiple r(2) ?=?0.64, p?=?0.006). GAG and neutral zone (NZ) modulus were identified as variables contributing to T1? (multiple r(2) ?=?0.28, p?=?0.08). When specimens with advanced degeneration were excluded from the multiple regression analysis, T2 was significantly predicted by compressive modulus, ?1, and water content (multiple r(2) ?=?0.71, p?=?0.009), while no variables were significant predictors in the model for T1?. These results indicate that quantitative MRI can detect changes in the mechanical and biochemical properties of the degenerated disc. T2 may be more sensitive to early stage degenerative changes than T1?, while both quantitative MRI parameters are sensitive to advanced degeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1382-1388, 2016.

SUBMITTER: Gullbrand SE 

PROVIDER: S-EPMC7398583 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature