T1ρ Magnetic Resonance Imaging and Discography Pressure as Novel Biomarkers for Disc Degeneration and Low Back Pain

Study Design. Prospective magnetic resonance imaging (MRI) study of patients low back pain (LBP) requiring discography as part of their routine clinical diagnoses and asymptomatic age-matched volunteers. Objective. To determine whether T-1 rho MRI and discography opening pressure (OP) are quantitative biomarkers of disc degeneration in LBP patients and in asymptomatic volunteers. Summary of Background Data. Disc degenerative disease, a common cause of LBP, is related to the patient's prognosis and serves as a target for therapeutic interventions. However, there are few quantitative measures in the clinical setting. Discography OP and T-1 rho MRI are potential biomarkers of disc degenerative disease related to biochemical composition of the intervertebral disc. Methods. The institutional review board approved all experiments, and informed consent was provided by each subject. Patients being treated for LBP (n = 17; 68 levels; mean age, 44 +/- 6 years; and range, 30-53) and control subjects (n = 11; 44 levels; mean age, 43 +/- 17 years; and range, 22-76) underwent T-1 rho and T2 MRI on a Siemens 3T Tim Trio clinical scanner (Siemens Medical Solutions, Malvern, PA). The LBP patients also received multilevel provocative discography before their MRI. OP was recorded as the pressure when fluid first enters the nucleus of the intervertebral disc. Results. T-1 rho was significantly lower in the painful discs (55.3 +/- 3.0 ms, mean +/- SE) from control (92.0 +/- 4.9 ms, P < 0.001) and nonpainful discs (83.6 +/- 3.2 ms, P < 0.001). Mean OP for the painful discs (11.8 +/- 1.0 psi, mean +/- SE) was significantly lower than that for nonpainful discs (19.1 +/- 0.7 psi, P < 0.001). Both T-1 rho and OP correlated moderately with Pfirrmann degenerative grade. Receiver-operating-characteristic area under the curve was 0.91 for T-1 rho MRI and 0.84 for OP for predicting painful discs. Conclusion. T-1 rho and OP are quantitative measures of degeneration that are consistent across both control subjects and LBP patients. A significant and strong correlation exists between T-1 rho values and in vivo OP measurements obtained by discography in LBP patients.