Influence of angulation on metacarpal bone mineral density measurements using digital X-ray radiogrammetry

Digital X-ray radiogrammetry (DXR) is a computer-assisted technique used to quantify cortical bone density of the metacarpals. The influence of metacarpal bone rotation and type of cast material on bone mineral density (BMD) measurements using the DXR technique was tested.

The bone mineral density of the hand was measured by DXR, and rotation error (DXR-RE) as coefficients of variation were calculated, to verify reliability and reproducibility of this radiogeometric technique to assess in particular minor disease-related changes in the metacarpal bone mass. The reproducibility of the DXR measurements was also investigated using different cast materials (mull, elastic, and plastic).

There were no significant changes in absolute values of DXR-BMD observed between 0 to [Formula: see text] angulation. The relative DXR-RE ranged between 0 % (degree 1) and 0.70 % (degrees 15 and 19) for DXR-BMD. Regarding the different cast materials, DXR-BMD revealed a coefficient of variation with 0.41 % (mull cast) and 0.21 % (elastic cast). For the plastic cast, the DXR technique was not able to perform an analysis of DXR-BMD.

The study revealed no significant influence of metacarpal rotation on the measurements of metacarpal bone mineral density as estimated by DXR. DXR measurements are not optimal when cast material is used. DXR can accurately quantify periarticular cortical bone mass. This is significant especially for rheumatoid arthritis and related conditions where X-ray imaging of arthritic hands with varying degrees of deformity is performed.