Comparative Study On Bone Density Of Lumbar Vertebrae By Quantitative Computed Tomography Without External Reference Phantom And Dual-energy X-ray Absorptiometry

Objective:Bone mineral density(BMD)of the lumbar vertebrae in the same group of subjects by using quantitative computed tomography(QCT)without external reference phantom and dual-energy X-ray absorptiometry(DXA)was measured.By comparing the differences between the two methods in measuring BMD and detecting osteoporosis and analyzing the correlation between the measurements of the two methods,to investigate the value of QCT without external reference phantom in practical clinical applications.Methods:The imaging data of 120 middle-aged female patients who had undergone both lumbar orthogonal DXA and whole lumbar spine CT scans at our hospital were retrospectively collected.BMD was measured using the CT scan data by bone density measurement software from Neusoft Corporation with less-phantom method.The BMD of each vertebrae of L1～L4 measured by DXA and QCT without external reference phantom was counted,ANOVA and correlation analysis were performed,and the difference in detection rate between the two was tested by chi-square test after diagnosing the type of osteoporosis of the patients by their respective criteria,.Results:(1)Bone density measurement results of QCT without external reference phantom and DXA:a BMD of L1～L4 vertebrae measured by DXA was not all equal(F=6.67,P<0.05),in ascending order was:L1<L2<L3<L4(0.78±0.16 g/mm2<0.83±0.22g/mm2<0.90±0.27 g/mm2<0.91±0.21 g/mm2);while the differences in v BMD of each vertebrae from L1～L4 measured by QCT without external reference phantom were not statistically significant(F=1.54,P>0.05).(2)Difference in osteoporosis detection rate between QCT without external reference phantom and DXA:diagnostic agreement rate between QCT without external reference phantom and DXA in patients’bone mass types was 74.2%,and inconsistent rates was25.8%.The difference in the detection rate of patients’bone mass types between the two methods was statistically significant(χ~2=75.52,P<0.05):for osteoporosis:QCT without external reference phantom>DXA(55.8%>40.8%);for osteopenia:QCT without external reference phantom>DXA(31.7%>30.8%).(3)Correlation analysis of QCT without external reference phantom and DXA:v BMD of L1,L2,L3 and L4 measured by QCT without external reference phantom was significantly positive with a BMD by DXA(P<0.05),the correlation coefficients were:r L1=0.92,r L2=0.91 r L3=0.89,r L4=0.88.Conclusion:BMD is a major clinical indicator for the diagnosis,monitoring and prevention of osteoporosis.When diagnosing osteoporosis by measuring bone mineral density,the results of QCT without external reference phantom not only correlate highly with DXA,the"gold standard"for diagnosing osteoporosis,but also has greater accuracy,sensitivity and specificity for bone densitometry than DXA,and has a higher detection rate for osteoporosis than the latter,so QCT without external reference phantom can be used as a better bone mineral density measurement tool to help physicians diagnose osteoporosis.