A feasibility study of in vivo T1ρ imaging of the intervertebral disc

PurposeRecent studies have proposed that magnetic resonance (MR) T1ρ relaxation time is associated with loss of macromolecules. The depletion of macromolecules in the matrix of the intervertebral disc may be an initiating factor in degenerative disc disease. The purpose of this study was to test the feasibility of quantifying T1ρ relaxation time in phantoms and intervertebral discs of healthy volunteers using in vivo MR imaging at 3 T.Materials and MethodsA multislice T1ρ spiral sequence was used to quantify T1ρ relaxation time in phantoms with different agarose concentrations and in the intervertebral discs of 11 healthy volunteers (mean age=31.3 years; age range=23–60 years; gender: 5 females, 6 males).ResultsThe phantom studies demonstrated the feasibility of using spiral imaging at 3 T. The in vivo results indicate that the median T1ρ value of the nucleus (116.6±21.4 ms) is significantly greater (P<0.05) than that of the annulus (84.1±11.7 ms). The correlations between the age of the volunteers and T1ρ relaxation time in the nucleus (r2=−0.82; P=0.0001) and the annulus (r2=−0.37; P=0.04) were significant. A trend of decreasing T1ρ values from L3–4 to L4–5 to L5–S1 was evident.ConclusionThe results of this study suggest that in vivo T1ρ quantification is feasible and may potentially be a clinical tool in identifying early degenerative changes in the intervertebral disc.