Reproducibility Of Bone Mineral Density Measurement By Quantitative CT Without External Reference Phantom And The Comparison With That Of DXA

Objectives The study aims to explore the following three objectives: 1)To compare the correlation for the bone mineral density(BMD)measured by quantitative CT(QCT)without external reference phantom and dual energy X-ray absorptiometry(DXA).2)To assess the diagnosis rate for osteoporosis by QCT without external reference phantom.3)To evaluate the intra-and inter-observer reproducibility of BMD measured by QCT without external reference phantom.Methods: The BMD measurement for 83 aged individuals was performed by QCT without external reference phantom and DXA.The correlation by the two measurements was evaluated to detect osteoporosis.31 of them were subjected to QCT-based BMD measurement twice by three trained spine surgeons.The intro-and inter-observer reproducibility of BMD measured by QCT without external reference phantom was evaluated..Results: 1.The results of BMD measured by QCT without external reference phantom in male patients,female patients and all patients were highly correlated with that of DXA.The correlation coefficients were 0.947,0.911 and 0.930 respectively and all P values were less than 0.05;2.The diagnosis rate for osteoporosis in specific sites including spine,proximal femur and the combination by DXA were 24.1%,21.7%,26.5% respectively.While the diagnosis rate for osteoporosis in the site of spine by QCT without external reference phantom was 38.6%.The diagnosis rate for osteoporosis was significantly different between three sites by DXA and the spine by QCT(P=0.010、0.009、0.019);3.The inter-differences for BMD measurement by three surgeon were 4.22%±2.55%,5.08%±3.83% and 4.16%±3.03% respectively.Variance analysis showed there were no statistically significant differences between inter-observer(P= 0.12,0.56,0.31).The intra-correlation coefficient showed that the two BMDs of the three measurements were highly stable(ICC=0.995,0.994,0.995).The BMD measured by three surgeons was no statistically significant different and highly stable(P=0.15,ICC=0.957,Cronbach’s alpha coefficient =0.985).Conclusion: The results of BMD measured by QCT without external reference phantom is highly correlated with that of DXA.The diagnosis rate for osteoporosis by QCT is higher than that by DXA.The BMD measured by QCT without external reference phantom have high reproducibility.QCT without external reference phantom is a potential evaluation tool for detecting osteoporosis in the aged population.