T1ρ Magnetic Resonance Imaging Quantification of Early Lumbar Intervertebral Disc Degeneration in Healthy Young Adults

Study Design. Cross-sectional study using T-1 rho magnetic resonance imaging (MRI) of lumbar spine in healthy young adults. Objective. To evaluate early intervertebral disc degeneration (IDD) quantified by T-1 rho- and T-2-weighted MRI in asymptomatic young adults and to correlate T-1 rho value with Pfirrmann degenerative grade, sex, and body mass index (BMI). Summary of Background Data. Intervertebral disc starts early to degenerate losing proteoglycan content in the nucleus pulposus (NP). A potential tool for the study of early stage of IDD is T-1 rho MRI. T-1 rho relaxation time of human discs has been correlated to proteoglycan content in previous studies. Methods. T-1 rho- and T-2-weighted images of the lumbar spine were obtained for 63 asymptomatic young subjects (34 men and 29 women; mean age, 22.95 +/- 1.8 yr), with a 1.5-T MRI scanner. T-1 rho mapping and values in the NP and anulus fibrosus (n = 315) were obtained. Degenerative grade was assessed using T-2-weighted images, according to the Pfirrmann scale. Differences in T-1 rho value between sexes, BMI, and linear regression analyses with degenerative grade were determined. Results. T-1 rho values of NPs were significantly higher than those of anulus fibrosus at all levels. T-1 rho values were significantly lower in women at L3-L4 and L4-L5 discs (P < 0.05). T-1 rho values decreased linearly with degenerative grade. However, nondegenerated discs (Pfirrmann grades 1 and 2) showed a wide range of T-1 rho relaxation time. No significant correlation was observed between T-1 rho value and BMI. Conclusion. The data of this study showed a significant difference in IDD onset between sexes. T-1 rho values correlate with Pfirrmann degenerative grade in young adults. However, the wide distribution of T-1 rho values in healthy intervertebral disc highlights the low sensitivity of Pfirrmann grade to detect the early IDD changes. T-1 rho can be potentially used as a clinical tool to identify early IDD and to create a reliable quantitative scale.