CT能谱成像技术定量测定羊骨骨密度的可行性

Feasibility and accuracy of bone density measurement by CT spectral imaging: an in vitro study on sheep bone

目的利用CT能谱成像(gemstone spectral imaging,GSI)技术定量分析测定骨密度的可行性及准确性。方法新鲜羊离体腰椎体骨5付,每付4个椎体作为一组,首先分别对每组羊骨使用双能量X线吸收法(dual-energy X-ray absorptiometry,DXA)进行扫描,获得每块羊骨的骨密度值(bone mineral density,BMD);再将每组羊骨放置于CT机中,采用GSI模式进行扫描,利用能谱成像物质分离技术测量每块羊骨的钙含量;最后将每块羊骨测定体积后进行高温灰化并称重,计算出每块羊骨的骨灰密度值,采用骨灰钙含量作为金标准,将GSI、DXA方法测得结果分别与之进行对照分析,即采用均行pearson相关性分析法,计算GSI技术、DXA与骨灰钙含量之间的相关度。结果 GSI及DXA扫描所得的各种测量数据与骨灰Ca含量均呈线性正相关(P<0.01),GSI技术测量结果与骨灰Ca含量的相关度为(r=0.879),稍高于DXA测量值的相关度(r=0.845)。结论 CT能谱成像在离体羊骨骨密度的定量分析方面,准确性优于DXA骨密度测量方法,有望应用于人体骨骨密度的定量测量。

Objective To evaluate the feasibility and accuracy of bone mineral density measurement by gemstone spectral CT （GSI）. Methods 5 isolated fresh sheep lumbar vertebral body bone, including 4 vertebras for each bone, were used in this study. Each bone was scanned with both gemstone spectral CT （ Discovery CT 750HD, GE healthcare） and DXA （ Dual energy X- ray absorptiometry）. Then, each bone got high temperature incineration and weighed, bone density was calculated. For CT data, monochromatic images were reconstructed; the bone calcium content was measured on quantitative calcium/water-based material decomposition images with a dedicated software （GSI Viewer）. Using calcium content of bone ash as the gold standard, pearson correlation analysis was taken for the calcium content of GSI and BMD value of DXA are respectively. Results Both calcium con- tent of GSI and BMD value of DXA had high positive-correlation with calcium content of bone ash （ both P 〈 0.01 ）. The correla- tion efficient of calcium content of GSI （ r =0. 879） was slight higher than that of BMD value of DXA（ r =0. 845）. Conclusion Quantitative calcium content t by gemstone spectral CT provides compatible accuracy with bone mineral density meas- urement of DXA. So it is prosperous for GSI applied for quantitative measurement of mineral density of human bones.