23 Na-magnetic resonance imaging of the human lumbar vertebral discs: in vivo measurements at 3.0 T in healthy volunteers and patients with low back pain

Abstract Background context1 H magnetic resonance imaging (MRI) of the spine can rule out common causes of low back pain (LBP), such as disc protrusions or nerve root compression; however, no significant causal relation exists between morphology and the extent of symptoms. Functional MRI techniques, such as23 Na, may provide additional information, allowing indirect assessment of vertebral glycosaminoglycan concentrations, decreases in which are associated with early degenerative changes. Purpose To evaluate23 Na-MRI of asymptomatic healthy volunteers and symptomatic patients with LPB and correlate the results to the Pfirrmann classification of MRI disc morphology. Study design Retrospective cohort study at an academic medical center. Patient sample Two groups were studied: (1) 55 healthy volunteers (31 men, 24 women; mean age 28.8 years) and (2) 12 patients (6 men, 6 women; mean age: 35.3 years) with a recent history of LBP. Methods Lumbar spines of the aforementioned groups were examined on a 3.0 T MRI scanner with morphological1 H and23 Na imaging. Intervertebral disc (IVD)23 Na at each level was normalized (23 Nanorm ). Distribution and differences between mean23 Nanorm corresponding to each Pfirrmann classification were evaluated in the two study groups (analysis of variance). Linear correlations between23 Nanorm , body mass index (BMI), and age were assessed (Pearson correlation coefficient). Gender-dependent differences were evaluated (paired t test). Outcome measures Physiological measure: IVD23 Nanorm as determined by23 Na-MRI. Results A normal distribution of23 Nanorm was confirmed for both groups (p=.072 and p=.073, respectively). The mean Pfirrmann score statistically significantly differed between them (p