Dual-energy digital radiography in the assessment of bone mechanical properties

Abstract

At present, bone fragility and fracture risk are estimated with bone mineral density (BMD), measured by dual-energy x-ray absorptiometry (DXA). It is known that DXA-based BMD (BMDDXA) has a relationship with mechanical characteristics of bone. Dual-energy digital radiography (DEDR) has also been shown to be a potential method to determine BMD, but the ability of DEDR-based BMD (BMDDEDR) to predict bone mechanical properties is not yet known. In this study, we investigated the ability of BMDDEDR to predict the mechanical characteristics of bone. Reindeer femora (N = 50) were imaged at two different energies (79 and 100 kVp) using a clinical digital radiography system. BMD was determined in four regions from these images using the DXA calculation principle. Femora were mechanically tested using axial loading configuration. Mechanical parameters were correlated with the BMDDEDR and BMDDXA of the femoral neck (FNBMDDEDR and FNBMDDXA). FNBMDDEDR and FNBMDDXA both correlated moderately with mechanical parameters. The highest correlations were found with maximal load (r = 0.53 and r = 0.65, p < 0.01, respectively). No statistically significant differences were found between the correlation coefficients when comparing the FNBMDDEDR or FNBMDDXA values and mechanical parameters. The correlation coefficient between BMDDEDR and BMDDXA varied between r = 0.56 and 0.86 (p < 0.01) in different regions of the upper femur. In conclusion, BMDDEDR predicts the mechanical parameters of reindeer bone with similar accuracy as BMDDXA.