Volumetric DXA (VXA): A new method to extract 3D information from multiple in vivo DXA images

Omar Ahmad, Krishna Ramamurthi, Kevin E. Wilson, Klaus Engelke, Richard L. Prince, Russell H. Taylor

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Three-dimensional geometric and structural measurements of the proximal femur are of considerable interest in understanding the strength of the femur and its susceptibility to fracture. Quantitative computed tomography (QCT) with a small voxel size (≤mm per side) is the current "gold standard" to examine the macrostructure of the femur, but it has a high effective radiation dose (approximately 2 to 5 mSv) and cost. Volumetric dual-energy X-ray absorptiometry (VXA) uses a commercially available DXA system (Hologic Discovery A) to reconstruct the proximal femur from four DXA scans delivering an effective radiation dose of 0.04 mSv. VXA was compared with QCT (voxel size of 0.29 × 0.29 × 1mm) in 41 elderly women (age 82±2.4 years) at slices located at the femoral neck and trochanteric regions of interest. For parameters of shape, the femoral neck axis length (FNAL) and the cross-sectional slice area (SA), accuracy and strong linear correlations (r=0.84 to 0.98) were demonstrated. Similar correlations (r=0.81 to 0.97) were observed for the density parameters, the cross-sectional bone area (CSA) and volumetric bone mineral density (vBMD). VXA also demonstrated strong correlations (r=0.76 to 0.99) for the engineering parameters of the minimum, maximum, and polar cross-sectional moments of inertia (CSMIs) and the section modulus (Z). We conclude that VXA is capable of generating a variety of 3D geometric and structural measurements that are highly correlated with QCT in elderly subjects in vivo. Moreover, the VXA measurements can be made with a commercially available DXA device at a very low radiation dose.

Original languageEnglish (US)
Pages (from-to)2744-2751
Number of pages8
JournalJournal of Bone and Mineral Research
Issue number12
StatePublished - Dec 2010


  • Bone Densitometry
  • Bone Structure
  • DXA
  • Hip Structure Analysis
  • QCT

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine


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