title: The use of routine non density calibrated clinical computed tomography data as a potentially useful screening tool for identifying patients with osteoporosis.
abstract: OBJECTIVE
  To evaluate whether lumbar vertebral body density CT attenuation values measured in Hounsfield Units (HUs) on routine Computed Tomography (CT) examinations can be reliably measured with limited variability, and to evaluate for a correlation between HUs and bone mineral density as measured by dual energy X-ray absorptiometry (DXA) scan.
  
  
  METHODS
  Retrospective review of a total of 249 routine MDCT examinations, performed to measure HUs at the first non-rib bearing lumbar vertebral body on axial images, cross-referenced to the lateral scout image.
  
  
  RESULTS
  The overall ICC and RC for intra-reader variability on CT HU were 0.987 (95% CI 0.973 - 0.999) and 15.664 (95% CI 11.66-16.97). The overall ICC and RDC for inter-reader variability on CT HU were 0.952 (95% CI 0.892 - 0.999) and 30.20 (95% CI 23.73 - 34.48). The ICC and RC for interscanner variability were 0.98 (95% CI 0.95 - 0.99) and 16.67 (95% CI 13.13 - 22.85). The correlation between the L1 HUs and L1 BMD, L1 t-score, and overall t-score was 0.437, 0.392, and 0.400, respectively.
  
  
  CONCLUSIONS
  CT attenuation values of the first lumbar vertebra can be measured on routine abdomen CTs with limited variability despite multiple readers and scanners. Correlation between HU and BMD as measured by DXA scan was only weakly positive, and by this method measuring the density of a lumbar vertebral body from a routine MDCT scan does not provide the sensitivity or specificity necessary for a screening test. However above a certain measured value (180 HU), patients have a low chance of osteoporosis and therefore may not need additional screening, potentially limiting radiation exposure and cost.
authors.affiliation: Hospital for Joint Diseases, NYU Langone Medical Center, Department of Radiology, Division of Musculoskeletal Radiology, NY, NY, USA.
authors.forename: Christopher John
authors.initials: CJ
authors.lastname: Burke
authors.affiliation: Duke University Medical Center, Department of Radiology, Division of Musculoskeletal Radiology, Durham, NC, USA.
authors.forename: Manjiri M
authors.initials: MM
authors.lastname: Didolkar
authors.affiliation: Duke University, Department of Biostatistics and Bioinformatics, Duke Clinical Research Institute, Durham, NC, USA.
authors.forename: Huiman X
authors.initials: HX
authors.lastname: Barnhart
authors.affiliation: Duke University Medical Center, Department of Radiology, Division of Musculoskeletal Radiology, Durham, NC, USA.
authors.forename: Emily N
authors.initials: EN
authors.lastname: Vinson
keywords: bone mineral density; computed tomography; dual-energy X-ray absorptiometry; osteoporosis