T2 mapping and q-Dixon for assessment of intervertebral disc degeneration in lower back pain.

Background: Low back pain(LBP) is very common among the population, and intervertebral disc(IVD) degeneration is considered to be the most common cause of LBP, but the pathophysiological process between IVD degeneration and LBP is not very clear. We conducted this study to clarify the interplay between quantitative magnetic resonance imaging (MRI) parameters, including q-Dixon and T2 mapping, and clinical symptomatology in patients with LBP.

Methods: All LBP patients underwent lumbar spine MRI, encompassing q-Dixon and T2 mapping. The severity of pain was classified based on Oswestry Disability Index (ODI) scores. Midsagittal T2 and T2* mapping were used to assess anterior annulus fibrosus (AAF), nucleus pulposus (NP), and posterior annulus fibrosus (PAF), as well as vertebral bone marrow fat fraction (BMFF). ANOVA and Pearson's correlation analyses facilitated the comparative evaluation of MRI parameters with respect to Pfirrmann grades and ODI scores.

Results: 95 LBP patients were included (41 males, 54 females), with an average age of 44.39 ± 17.44. The T2 values of AAF and PAF were different and weakly correlated between most Pfirrmann grades (r = 0.435, 0.414). T2 and T2* values of NP were different and negatively correlated between all Pfirrmann grades (r=-0.844, -0.704), except for grade IV vs. V, revealing decreasing values for grades I-V. BMFF was different and moderately correlated (r = 0.646) between most Pfirrmann grades, except for grade V vs. grade III and IV. The T2 values of AAF, NP, and PAF, the T2* values of the NP, and the BMFF of the vertebrae could distinguish low pain from moderate and severe pain.

Conclusion: The T2 and T2* values of AAF, NP, PAF, as well as the BMFF of the vertebrae, can reflect intervertebral disc (IVD) degeneration and may be potentially used to quantitatively detect causes behind LBP.