Differences in IVD characteristics between low back pain patients and controls associated with HIZ as revealed with quantitative MRI

Background: Magnetic resonance imaging (MRI) can provide objective continuous intervertebral disc (IVD) measures in low back pain (LBP) patients. However, there are limited studies comparing quantitative IVD measures of symptomatic and asymptomatic individuals. Purpose: This study aimed to investigate possible differences in IVD tissue composition in patients with chronic LBP and controls using quantitative MRI and correlate IVD measures with the phenotype High-Intensity Zone (HIZ). Methods: The lumbar spine of 25 LBP-patients (25-69y, mean 38y, 11 males) and 12 controls (25-59y, mean 38y, 7 males) was examined with T2-mapping on a 1.5T MRI scanner. The mean T2-map value and standard deviation were determined in three midsagittal IVD slices and five sub-regions dividing each IVD in the sagittal plane. The distribution of T2-map values over the IVD was also determined with histogram analysis (Δμ = distribution width). Results: When compared to controls, patient IVDs displayed lower values for all metrics, with significant differences for the T2-map value, standard deviation (p = 0.026) and Δμ (p = 0.048). Significantly different T2-map values were found between cohorts in the region representing nucleus pulposus and the border zone between nucleus pulposus and posterior annulus fibrosus (p = 0.047–0.050). Excluding all IVDs with HIZs resulted in no significant difference between the cohorts for any of the analyzed metrics (p = 0.053–0.995). Additionally, the T2-map values were lower in patients with HIZ in comparison without HIZ. Conclusions: Differences in IVD characteristics, measured with quantitative MRI, between LBP patients and controls were found. The T2-differences may reflect altered IVD function associated with HIZ. Future studies are recommended to explore IVD functionality in relation to HIZ and LBP.