A Preliminary Study of DXA and QCT Derived Femur Cross-Section Stiffness

Dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) are the two clinic imaging modalities available for examining bone quality. However, there is a dilemma in their selection. DXA uses a lower and safer X-ray dosage, but the produced image is two-dimensional, the information of bone spatial geometry and heterogeneous material distribution required for evaluating bone quality is missing; On the other hand, although QCT is able to capture all the required information, it has to use amuch higher X-ray dosage that may be a potentialhealth concern. Femur cross-section stiffness is an important parameter forassessing bone quality. Although itcan be determined from both DXA and QCT image, it is best computed from QCT for the reason mentioned in the above. In this study, we attempted to establish the ‘equivalence’ between DXA and QCT derived femur cross-section stiffness. If it is successful, DXA can be used in replacement of QCT in assessing bone quality. The study results showed that there indeed exist strong correlations between DXA and QCT derived femur stiffness, but they are not equivalent to each other.