定量CT测量髋关节骨密度的重复性与DXA测量的一致性

目的 探讨定量CT（QCT）髋关节骨密度（BMD）测量重复性及与双能X线骨密度测定仪（DXA）测量的一致性.方法 随机抽取28名（男10例,女18例）老年受试者（男性＞60岁,女性＞50岁）,并分别采用QCT与DXA测量髋关节骨密度.收集左侧髋关节QCT扫描CT原始数据,分别由3名操作者各测量1次,其中1名操作者在不同时间重复测量3次,用于评价QCT髋关节骨密度结果的重复性.比较QCT和DXA测量左侧髋关节骨密度结果.结果 3名不同操作者或同一操作者不同时间采用QCT测量28名受试者左侧髋关节的骨密度值之间具有很好的相关性（ICC：0.93～0.98,P＜0.01）,全髋骨密度值之间差异无统计学意义.DXA与QCT测量的股骨颈和全髋骨密度结果之间具有显著相关性（r=0.88,0.89,P＜0.01）,DXA测量的骨密度值较QCT相对应骨密度值大10.5%和9.7%（t=7.53,9.68,P＜0.01）.上述骨密度值系统误差可被校正.结论采用QCT测量髋关节BMD具有较好的重复性,其BMD值与DXA所测BMD结果具有相关性.QCT髋关节（CTXA）骨密度测量可用于骨质疏松症的诊断和疗效随访,具有临床应用前景.

Reproducibility of hip bone mineral density measurement by quantitative CT and its consistency with DXA bone mineral density

Objective To evaluate the reproducibility of bone mineral density （ BMD ） in hip measured by quantitative CT （QCT） and the correlation with dual X-ray absorptionetry （DXA） measurements. Methods 28 elderly men and women were randomly selected from a prospective urban and rural epidermiology （ PURE ） study population. DXA and QCT scan of left hip were performed in the same day. CT raw data with QCT phantom scanned simultaneously were transferred to QCT workstation for analysis. In order to evaluate the reproducibility of QCT measm＇ements, 3 opera- tors performed the hip QCT BMD measurement with Mindways＇ QCT Pro software separately. One operator did nmasure- ment 3 times. Then, QCT results were compared with the DXA results to assess the consistency of these two methods. Re- sults The hip BMD measured with QCT by 3 independent operators or 3 times by one operator was highly correlated （ICC 0. 93 -0. 98, P 〈0. 01 ）, and the BMD results of the total hip between operators or repeat measurements did not differ significantly. The QCT BMD was highly correlated with the BMD measured by DXA （ r =0. 88, 0. 89, P 〈0. 01 ） , the absolute BMD value of DXA in the femoral neck and total hip were higher than those of QCT by 10. 5% and 9. 7% （t = 7.53, 9.68, P 〈 0. 01 ） and this systemic difference in absolute BMD value between QCT and DXA can be calibra-ted and the T score by these two methods will be comparable if appropriate reference data used. Conclusion Hip BMD measurements by QCT shows good reproducibility, and its results are comparable to DXA measurements. It validated the application of QCT hip BMD measurement for the diagnosis of osteoporosis.