title: BMD measurements of the spine derived from sagittal reformations of contrast-enhanced MDCT without dedicated software.
abstract: OBJECTIVE
  To assess QCT equivalent BMD of the lumbar spine in sagittal reformations of routine abdominal contrast-enhanced MDCT with simple PACS measurement tools and to apply this method to MDCT datasets for differentiating patients with and without osteoporotic vertebral fractures.
  
  
  METHODS
  Eight postmenopausal women (65±5 years) underwent standard QCT to assess BMD of L1-L3. Afterwards routine abdominal contrast-enhanced MDCT images of these women were obtained and apparent BMD of L1-L3 was measured using the sagittal reformations. The MDCT-to-QCT conversion equation for BMD was calculated with linear regression analysis. The conversion equation was applied to vertebral BMD datasets (L1-L3) of 75 postmenopausal women (66±4 years). Seventeen of the 75 patients had osteoporotic vertebral fractures.
  
  
  RESULTS
  BMD values of contrast-enhanced MDCT were on average 56 mg/ml higher than those of standard QCT. A correlation coefficient of r=0.94 (p<0.05) was calculated for the BMD values of MDCT and standard QCT with the conversion equation BMDQCT=0.69×BMDMDCT-11 mg/ml. Accordingly converted BMD values of patients with vertebral fractures were significantly lower than those of patients without vertebral fractures (69 mg/ml vs. 85 mg/ml; p<0.05). Using ROC analysis to differentiate patients with and without vertebral fractures, AUC=0.72 was obtained for converted BMD values (p<0.05). Short- and long-term reproducibility errors for BMD measurements in the sagittal reformations amounted 2.09% and 7.70%, respectively.
  
  
  CONCLUSIONS
  BMD measurements of the spine could be computed in sagittal reformations of routine abdominal contrast-enhanced MDCT with minimal technical and time effort. Using the conversion equation, the acquired BMD data could differentiate patients with and without osteoporotic vertebral fractures.
authors.affiliation: Institut für Röntgendiagnostik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München, Germany. thbaum@gmx.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Baum
authors.forename: Dirk
authors.initials: D
authors.lastname: Müller
authors.forename: Martin
authors.initials: M
authors.lastname: Dobritz
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Rummeny
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
authors.forename: Jan S
authors.initials: JS
authors.lastname: Bauer
mesh_terms: D000368:Aged; D019540:Area Under Curve; D015519:Bone Density; D003287:Contrast Media; D005260:Female; D006801:Humans; D007479:Iopamidol / Q000031:analogs & derivatives; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000293:injuries; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging*; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016103:Spinal Fractures / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol