title: Osteoporosis: diagnosis with lateral and posteroanterior dual x-ray absorptiometry compared with quantitative CT.
abstract: OBJECTIVE
  To compare the diagnostic sensitivity of posteroanterior and lateral dual x-ray absorptiometry (PA-DXA, L-DXA, respectively) and quantitative computed tomography (CT).
  
  
  METHODS
  Among 108 women undergoing lumbar spine bone mineral density assessment, 66 were healthy (mean age, 52.9 years +/- 1.2 [standard error of mean]) and 42 had osteoporosis (mean age, 66.9 years +/- 1.2).
  
  
  RESULTS
  Although both L-DXA and PA-DXA correlated well with quantitative CT (r = .73 and .72, respectively; P < .0001), L-DXA correlated better than PA-DXA with age (r = -.69 and -.50, respectively; P < .0001). Women with osteoporosis showed higher bone loss with quantitative CT (1.33% per year) and L-DXA (0.3% per year) than with PA-DXA (0.07% per year). Logistic regression analysis indicated that quantitative CT and L-DXA but not PA-DXA are significant predictors of osteoporotic fractures. Receiver-operating-characteristic curve analyses showed L-DXA to have a sensitivity and specificity closer to those of quantitative CT than did PA-DXA.
  
  
  CONCLUSIONS
  Performance of L-DXA helped discriminate better than PA-DXA between healthy subjects and those with osteoporosis.
authors.affiliation: Division of Bone and Mineral Diseases, Washington University School of Medicine, St Louis, MO.
authors.forename: G
authors.initials: G
authors.lastname: Guglielmi
authors.forename: S K
authors.initials: SK
authors.lastname: Grimston
authors.forename: K C
authors.initials: KC
authors.lastname: Fischer
authors.forename: R
authors.initials: R
authors.lastname: Pacifici
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015519:Bone Density; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging*; D012372:ROC Curve; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed