title: Correlation between Bone Mineral Density Measured by Dual-Energy X-Ray Absorptiometry and Hounsfield Units Measured by Diagnostic CT in Lumbar Spine.
abstract: OBJECTIVE
  Use of quantitative computed tomography (CT) to evaluate bone mineral density was suggested in the 1970s. Despite its reliability and accuracy, technical shortcomings restricted its usage, and dual-energy X-ray absorptiometry (DXA) became the gold standard evaluation method. Advances in CT technology have reduced its previous limitations, and CT evaluation of bone quality may now be applicable in clinical practice. The aim of this study was to determine if the Hounsfield unit (HU) values obtained from CT correlate with patient age and bone mineral density.
  
  
  METHODS
  A total of 128 female patients who underwent lumbar CT for back pain were enrolled in the study. Their mean age was 66.4 years. Among them, 70 patients also underwent DXA. The patients were stratified by decade of life, forming five age groups. Lumbar vertebrae L1-4 were analyzed. The HU value of each vertebra was determined by averaging three measurements of the vertebra's trabecular portion, as shown in consecutive axial CT images. The HU values were compared between age groups, and correlations of HU value with bone mineral density and T-scores were determined.
  
  
  RESULTS
  The HU values consistently decreased with increasing age with significant differences between age groups (p<0.001). There were significant positive correlations (p<0.001) of HU value with bone mineral density and T-score.
  
  
  CONCLUSIONS
  The trabecular area HU value consistently decreases with age. Based on the strong positive correlation between HU value and bone mineral density, CT-based HU values might be useful in detecting bone mineral diseases, such as osteoporosis.
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea. ; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea. ; Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
authors.forename: Sungjoon
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea. ; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea. ; Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
authors.affiliation: Department of Medical Statistics, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: So Hee
authors.initials: SH
authors.lastname: Oh
authors.affiliation: Department of Neurosurgery, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Park
keywords: Bone mineral density; Computed tomography; Hounsfield unit; T-score