title: Opportunistic screening for osteoporosis using abdominal computed tomography scans obtained for other indications.
abstract: BACKGROUND
  Osteoporosis is a prevalent but underdiagnosed condition.
  
  
  OBJECTIVE
  To evaluate computed tomography (CT)-derived bone mineral density (BMD) assessment compared with dual-energy x-ray absorptiometry (DXA) measures for identifying osteoporosis by using CT scans performed for other clinical indications.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Single academic health center.
  
  
  METHODS
  1867 adults undergoing CT and DXA (n = 2067 pairs) within a 6-month period over 10 years.
  
  
  METHODS
  CT-attenuation values (in Hounsfield units [HU]) of trabecular bone between the T12 and L5 vertebral levels, with an emphasis on L1 measures (study test); DXA BMD measures (reference standard). Sagittal CT images assessed for moderate-to-severe vertebral fractures.
  
  
  RESULTS
  CT-attenuation values were significantly lower at all vertebral levels for patients with DXA-defined osteoporosis (P < 0.001). An L1 CT-attenuation threshold of 160 HU or less was 90% sensitive and a threshold of 110 HU was more than 90% specific for distinguishing osteoporosis from osteopenia and normal BMD. Positive predictive values for osteoporosis were 68% or greater at L1 CT-attenuation thresholds less than 100 HU; negative predictive values were 99% at thresholds greater than 200 HU. Among 119 patients with at least 1 moderate-to-severe vertebral fracture, 62 (52.1%) had nonosteoporotic T-scores (DXA false-negative results), and most (97%) had L1 or mean T12 to L5 vertebral attenuation of 145 HU or less. Similar performance was seen at all vertebral levels. Intravenous contrast did not affect CT performance.
  
  
  CONCLUSIONS
  The potential benefits and costs of using the various CT-attenuation thresholds identified were not formally assessed.
  
  
  CONCLUSIONS
  Abdominal CT images obtained for other reasons that include the lumbar spine can be used to identify patients with osteoporosis or normal BMD without additional radiation exposure or cost.
  
  
  BACKGROUND
  National Institutes of Health.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Avenue, Madison, WI 53792-3252, USA. ppickhardt2@uwhealth.org
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: B Dustin
authors.initials: BD
authors.lastname: Pooler
authors.forename: Travis
authors.initials: T
authors.lastname: Lauder
authors.forename: Alejandro Muñoz
authors.initials: AM
authors.lastname: del Rio
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bruce
authors.forename: Neil
authors.initials: N
authors.lastname: Binkley
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D050815:Fractures, Compression / Q000000981:diagnostic imaging; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging; D012372:ROC Curve; D011860:Radiography, Abdominal; D016103:Spinal Fractures / Q000000981:diagnostic imaging