STUDY DESIGN: Retrospective radiological analysis OBJECTIVE: To analyze the distribution of computed tomography (CT)-based Hounsfield unit (HU) values of lumbar vertebrae and explore the correlation between HU values and the modified Pfirrmann grades in patients with degenerative lumbar spinal stenosis (DLSS). METHOD: A total of 82 DLSS patients were divided into two gender-based groups for this retrospective analysis. Demographic data, including age, gender, body mass index, medical history, smoking status, operative levels, bone turnover markers (BTMs), and bone metabolism indicators, of all the patients were collected. HU values of the L1-midline, L2-midline, L1 lower subendplate, upper and lower subendplates of L2-L5, and S1 upper subendplate were obtained based on lumbar CT in DLSS patients. The modified Pfirrmann grading system was used to classify the disc degeneration observed in the magnetic resonance imaging (MRI) of DLSS patients. RESULTS: The demographic data, including age, BTMs, bone metabolism indicators, and HU values of the L1- and L2-midlines, showed no significant differences between the male and female DLSS patients. The L1-midline HU value was positively correlated with the Ca levels and negatively correlated with the β-CTX levels in both male and female DLSS patients. The L2-midline HU value was positively correlated with all the lumbar HU values in male DLSS patients. The Pfirrmann grades of all the lumbar discs showed a significant correlation. Additionally, the Pfirrmann grades of L1-L2 to L5-S1 discs were higher in males than in females, but the difference was not statistically significant. Moreover, the Pfirrmann grades showed an increasing trend with age in all lumbar discs, especially in the L1-L2, L2-L3, and L3-L4 segments. The L3-L4 and L5-S1 Pfirrmann grades were positively correlated with the HU values of the corresponding adjacent vertebral subendplates. The differences in the HU values of the adjacent vertebral subendplates were negatively correlated with severe intervertebral disc degeneration (IDD), compared to mild-to-moderate IDD, especially in Pfirrmann grade VIII cases. CONCLUSION: The Pfirrmann grades of the lumbar discs were positively correlated in DLSS patients and showed an increasing trend with age, especially in the L1-L2, L2-L3, and L3-L4 segments. Additionally, the HU values of the adjacent vertebral subendplate were positively correlated with the Pfirrmann grades of the L3-L4 and L5-S1 discs. Relatively lower HU values of the caudal subendplate was associated with severe IDD, and bone mineral density(BMD) in the caudal subendplate correlated with preserving disc height.
Song et al. (Wed,) studied this question.