European Spine Journal

, Volume 14, Issue 10, pp 971–976 | Cite as

Accuracy of DXA scanning of the thoracic spine: cadaveric studies comparing BMC, areal BMD and geometric estimates of volumetric BMD against ash weight and CT measures of bone volume

  • Meena M. Sran
  • Karim M. Khan
  • Kathy Keiver
  • Jason B. Chew
  • Heather A. McKay
  • Thomas R. Oxland
Original Article

Abstract

Biomechanical studies of the thoracic spine often scan cadaveric segments by dual energy X-ray absorptiometry (DXA) to obtain measures of bone mass. Only one study has reported the accuracy of lateral scans of thoracic vertebral bodies. The accuracy of DXA scans of thoracic spine segments and of anterior-posterior (AP) thoracic scans has not been investigated. We have examined the accuracy of AP and lateral thoracic DXA scans by comparison with ash weight, the gold-standard for measuring bone mineral content (BMC). We have also compared three methods of estimating volumetric bone mineral density (vBMD) with a novel standard–ash weight (g)/bone volume (cm3) as measured by computed tomography (CT). Twelve T5–T8 spine segments were scanned with DXA (AP and lateral) and CT. The T6 vertebrae were excised, the posterior elements removed and then the vertebral bodies were ashed in a muffle furnace. We proposed a new method of estimating vBMD and compared it with two previously published methods. BMC values from lateral DXA scans displayed the strongest correlation with ash weight (r=0.99) and were on average 12.8% higher (p<0.001). As expected, BMC (AP or lateral) was more strongly correlated with ash weight than areal bone mineral density (aBMD; AP: r=0.54, or lateral: r=0.71) or estimated vBMD. Estimates of vBMD with either of the three methods were strongly and similarly correlated with volumetric BMD calculated by dividing ash weight by CT-derived volume. These data suggest that readily available DXA scanning is an appropriate surrogate measure for thoracic spine bone mineral and that the lateral scan might be the scan method of choice.

Keywords

DXA Accuracy Thoracic spine Ash weight Bone volume 

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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Meena M. Sran
    • 1
    • 2
    • 3
  • Karim M. Khan
    • 2
    • 4
  • Kathy Keiver
    • 5
  • Jason B. Chew
    • 6
  • Heather A. McKay
    • 2
    • 7
  • Thomas R. Oxland
    • 1
    • 7
    • 8
  1. 1.Division of Orthopaedic Engineering Research, Department of Orthopaedics, Faculty of MedicineUniversity of British Columbia and the Vancouver Coastal Health Research InstituteVancouverCanada
  2. 2.Bone Health Research GroupUniversity of British Columbia and the Vancouver Coastal Health Research InstituteVancouverCanada
  3. 3.Department of MedicineUniversity of British ColumbiaVancouverCanada
  4. 4.Department of Family PracticeUniversity of British ColumbiaVancouverCanada
  5. 5.Food, Nutrition and HealthUniversity of British ColumbiaVancouverCanada
  6. 6.Department of RadiologyUniversity of British Columbia and the Vancouver Hospital and Health Sciences CentreVancouverCanada
  7. 7.Department of OrthopaedicsUniversity of British Columbia and the Vancouver Coastal Health Research InstituteVancouverCanada
  8. 8.Department of Mechanical EngineeringUniversity of British ColumbiaVancouverCanada

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