Role of Magnetic Resonance Spectroscopy and T2 Relaxometry as Imaging Biomarker of Early Lumbar Intervertebral Disc Degeneration

Study design: Observational comparative study.

Objective: To study the role of magnetic resonance spectroscopy (MRS) and T2 relaxometry (T2r) as imaging biomarkers for identifying early lumbar disc degeneration.

Methods: We evaluated 236 discs in normal volunteers and 215 discs in low back pain (LBP) patients by MRS and T2r to document the molecular spectra of various metabolites as well as disc hydration and collagen content, respectively. All volunteer discs were Pfirrmann grade 1 (PF1), whereas patients with LBP had PF 1 (n = 156) and PF 2 (n = 59). The study population was compared in three age groups: A (20-30 years), B (30-40 years), and C (40-50 years).

Results: T2r, an indicator of collagen and hydration, was higher in volunteers (121.8 ± 31.1), compared to PF 1 patients (110.68 ± 23.96) and PF 2 patients (90.15 ± 25.81) (P = 0.001). Proteoglycan assessed by MRS was more stable for volunteers (3.39 ± 1.69) and PF 1 patients (3.6 ± 1.69) but reduced in PF 2 patients (2.86 ± 1.47), showing that structural molecules did not alter within the PF 1. However, lactate and other metabolites showed a difference even within PF1 between volunteers and LBP patients. We were able to identify a unique subset of PF 1 that had a normal value of proteoglycan and T2r but altered metabolite distribution, which may represent early disc degeneration (DD).

Conclusion: MRS and T2r can be used as imaging biomarkers for early DD by identifying altered metabolic activity with an intact matrix.