课题背景：骨质疏松症的诊断标准一直为学者们所关注，鉴于目前生化检查尚不能作为诊断指标，故骨矿含量测定或骨密度测定成为目前诊断骨质疏松的重要手段，而骨矿含量的测定方法多种多样，其临床应用方面还有许多相关问题值得商榷，在质控方面及诊断骨质疏松的敏感指标的问题就是其中之一。国内较多报道了体质量、身高对骨量的影响，但对双能X线骨密度测量仪测定中骨矿含量、骨密度、骨矿含量/椎体宽诊断骨质疏松的敏感性报道较少。

应用要点：实验结果表明：①在诊断骨质疏松时，骨密度能反映骨矿含量、骨矿含量/椎体宽在骨量及累积丢失率的变化。②骨密度的变异系数值、有临床意义的最小变化率最小。③骨密度为双能X线骨密度测量仪测定诊断骨质疏松更敏感指标。

相关链接：骨密度仪的差异或漂移可以通过质控加以校正。骨密度仪自身的纵向质控可依照生产厂家的说明书进行。目前，许多机构在做多中心或多地区的骨矿测量用于诊断和治疗随访的研究，但不同地区、不同厂家的骨密度仪如何参照对比是一直存在的问题，现还不能用一个固定的模式来解决这类问题，只有在做多中心研究同时进行横向质控才可在一定程度上解决这方面的问题。若要比较多中心或多地区的骨矿测量的诊治结果，质控实施势在必行。

摘要
目的:通过DPX-MD双能X射线骨密度仪测量腰椎铝体模、活体腰椎、带软组织死体腰椎骨矿密度、骨矿含量、骨矿含量/椎体宽的短期精密度及其最小变化率差异比较，探索双能X线吸收法骨密度测定仪测定诊断骨质疏松症的敏感指标。
方法：实验于2004-05/2006-12在川北医学院人体解剖实验室与川北医学院附属医院内分泌科骨密度室完成。①实验材料：铝体模为双能X线骨密度仪（DPX-MD，美国Lunar公司）所配备的自检模块；3个活体椎体分别来源于38岁骨密度正常男性，40岁骨质疏松症男性，62岁轻微骨量减少女性，均为自愿参与实验的川北医学院附属医院医生；1个带软组织的死体椎体，由川北医学院人体解剖实验室提供。②测量方法及评估：采用的双能X射线骨密度仪测量各椎体的骨密度。3次/d，连续测定5 d。铝体模和死体椎体两端均用小木块固定在6.5 cm的高度，放在15 cm的水浴中，为减少误差由一人操作。由不同骨矿含量、骨矿含量/椎体宽、骨矿密度可得到各自的变异系数，由不同的变异系数可得到有临床意义的最小骨矿含量、骨矿含量/椎体宽、骨矿密度变化率，由不同的变异系数及不同的最小变化率比较来判断诊断骨质疏松的敏感指标。
结果：①铝体模和正常男性椎体的骨矿密度、骨矿含量均高于轻微骨量减少女性椎体、骨质疏松症男性椎体和死体椎体，且以死体椎体骨矿含量最低。②各椎体或L2~4骨矿密度变异系数均比骨矿含量、骨矿含量/椎体宽变异系数小。③各椎体和L2~4的有临床意义的最小骨矿密度变化率值均比各椎体和L2~4的有临床意义的骨矿含量、骨矿含量/椎体宽变化率值小。
结论：从短期精密度及有临床意义的最小变化率比较可以看出，无论是仪器的自检模块铝体模还是骨密度正常男性椎体、骨质疏松症男性椎体、轻微骨量减少但有骨质增生女性椎体、严重骨质疏松死体椎体，各椎体和L2~4变异系数值与有临床意义的最小变化率值骨矿密度的改变均比骨矿含量、骨矿含量/椎体宽的改变小，那么它在质量控制中受到的影响更小。双能X线骨密度测量仪测定中骨矿密度更能较好反应骨矿含量、骨矿含量/椎体宽变化，是诊断骨质疏松症的敏感指标。
关键词：骨密度；光密度测定法；腰椎；骨质疏松；组织构建

康后生，左莹，孙昆，邱平，任伶俐，严宗逊，毛淑芳.双能X线骨密度测定仪测定腰椎铝体模、在体及离体腰椎骨矿密度、
含量及含量/椎体宽短期精密度及最小变化率差异比较[J].中国组织工程研究与临床康复，2008，12(11):2015-2020
[www.zglckf.com/zglckf/ejournal/upfiles/08-11/11k-2015(ps).pdf]

Short-term precision and minimal change rate of bone mineral density, bone mineral content and content/vertebral width in living, dead and aluminum models of lumbar vertebra: Detection using DPX-MD dual-energy X-ray densitometry

Abstract

AIM：To explore the sensitive indexes for the diagnosis of osteoporosis by the comparison in the short-term precision and minimal change rate of bone mineral density (BMD), bone mineral content (BMC), BMC/vertebral width (W) in aluminum model of lumbar vertebra, living lumbar vertebra, and dead lumbar vertebra with soft tissue by DPX-MD dual-energy X-ray densitometry.
METHODS: From May 2004 to December 2006, the experiment was performed in the BMD Laboratory of Endocrinology Department at Affiliated Hospital of North Sichuan Medical College and the Laboratory of Human Anatomy in North Sichuan Medical College. ①Aluminum model was the self-test module prepared by the dual-energy X-ray densitometry station (DPX-MD, Lunar, U.S.); 3 living lumbar vertebra were from a 38-year-old male with normal BMD, a 40-year-old male with osteoporosis, and a 62-year-old female with light osteopenia, respectively, who were the doctors in the Affiliated Hospital. One dead vertebra with soft tissue was offered by the Laboratory of Human Anatomy in North Sichuan Medical College. ②DPX-MD dual energy X-ray bone densitometry was used to measure the BMC of each lumbar vertebra, three times daily for five successive days. The two ends of the aluminum model and dead vertebra were fixed using small wood block at a height of 6.5 cm, and put in waterbath of 15 cm. These operations were performed by the same person to avoid errors. Individual variation coefficient was obtained from different BMC, BMC/W and BMD, and the change rate with significance in clinic of minimal BMC, BMC/W and BMD was obtained based on the variation coefficient, both of which were used to determine the sensitive indexes from osteoporosis.
RESULTS: ①The BMD and BMC in aluminum model and normal male vertebra were higher than those in female vertebra with light osteopenia, male vertebra with osteoporosis and dead vertebra, and the BMC in dead vertebra was the lowest. ②The variation coefficients of BMC in each vertebra or L2-4 were lower that those of BMC and BMC/W. ③The minimal change rate of BMD with clinical significance in each lumbar vertebra or L2-4 was lower than that of BMC and BMC/W.
CONCLUSION: Based on the short-term precision and minimal change rate with clinical significance, the change in variation coefficient and minimal change rate of BMD in each vertebra or L2-4 is lower than that of BMC and BMC/W in the self-test aluminum model, male vertebra with normal BMD, male vertebra with osteoporosis, female vertebra with light osteopenia and dead vertebra with severe osteoporosis. Therefore, it is lightly influenced in quality control. In the detection by DPX-MD dual energy X-ray bone densitometry, BMD can better reflect the changes in BMC and BMC/W, so it can serve as the sensitive index for diagnosing osteoporosis.

Kang HS, Zuo Y, Sun K, Qiu P, Ren LL, Yan ZX, Mao SF.Short-term precision and minimal change rate of bone mineral density, bone mineral content and content/vertebral width in living, dead and aluminum models of lumbar vertebra: Detection using DPX-MD dual-energy X-ray densitometry.Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(11):2015-2020(China) [www.zglckf.com/zglckf/ejournal/upfiles/08-11/11k-2015(ps).pdf]