Reliability of Hounsfield Unit for Assessing Asymmetrical Vertebral Bone Mass in Adult Degenerative Scoliosis

OBJECTIVE: Hounsfield Unit (HU) has been used to investigate the asymmetrical vertebral bone mass in patients associated with adult degenerative scoliosis (ADS). Therefore, there is an inevitable need to evaluate the performance of HU values in ADS subjects. METHODS: A total of 162 patients (81 ADS patients and 81 non-ADS patients) aged ≥50 years undergoing the CT examination were reviewed. The HU values of the lumbar vertebral body (including total, convex side, and concave side) at bilateral pedicle plane were obtained and compared. The paired t-test, chi-squared test, independent samples t-test, and interclass correlation coefficient (ICC) were used for statistical analyses. RESULTS: The HU values were significantly different between the convex and concave sides of the lumbar vertebral body (P < 0.01). The total prevalence of osteoporosis (OP) in ADS patients was higher than that of non-ADS patients. The prevalence of OP in female or male of ADS patients was higher than that of non-ADS patients, respectively. Intra- and inter-rater reliability were very strong (both >0.8) for measuring asymmetrical vertebral bone mass in ADS patients. CONCLUSION: HU value was a high reproducibility method for evaluating the vertebral bone mass in ADS patients. The HU values at the concave sides were significantly higher than that of convex sides at the lumbar vertebral body on the pedicle plane. The prevalence of OP in ADS patients was higher than that of non-ADS patients, especially for females associated with ADS. Moreover, the static asymmetric load did not enhance the bone mass at the concave side compared with the left/right side of non-ADS patients.