双能X线吸收比色法测量骨密度的临床应用

双能Ｘ线吸收比色法近年来越来越广泛地应用于骨密度测量，并以精确度高、低放射性、省时而优于其它方法。直接对髋部等部位骨胳进行骨密度测量，使利用骨密度测量骨折、研究骨质疏松更为可靠。该方法还可用于骨再生过程的定量观察及骨改建过程的研究。     

双能X线吸收法及定量CT法诊断骨质疏松症的比较研究

本研究比较了双能Ｘ线吸法（ＤＸＡ）与定量ＣＴ（ＱＣＴ）在骨质疏松症诊断中的应用。对５６例健康妇女（Ｈ组）及４８例骨折后骨质疏松妇女（ＯＰ组）进行了ＤＸＡ及ＱＣＴ测量。ＤＸＡ与ＱＣＴ在Ｈ、ＯＰ组均显著相关（ｒ＝０．７５，Ｐ＜０．０００１，ｒ＝０．５８，Ｐ＜０．０００１）。Ｈ组及ＯＰ组，随年龄增长的骨减少率，ＱＣＴ较ＤＸＡ法为高。而两组中骨密度的差别，ＱＣＴ较ＤＸＡ法更大（Ｐ＜０．０５）。结论；由于ＱＣＴ可以选择性测量椎体松质骨，故可较ＤＸＡ更能很好地区分健康人与骨质疏松病人。     

双能X线吸收法腰椎侧位骨密度测定的临床研究

目的评价双能X线吸收法测定腰椎骨密度时侧位的临床价值。方法178例女性患者(按年龄分组)接受腰椎后前位和侧位骨密度测定,以BMD表示骨密度值,以T值为标准判断骨量正常、骨量减少和骨质疏松,评价腰椎后前位与侧位T值对骨量减少程度的判断和骨质疏松诊断的差别。结果①各年龄组患者腰椎后前位BMD值均高于侧位值;②各年龄组患者腰椎后前位及侧位T值对骨量减少程度的判断有显著性差别;③当大于50岁时,腰椎后前位及侧位T值对骨质疏松诊断有显著性差别。结论腰椎侧位对女性患者骨量减少程度的判断和骨质疏松的诊断(>50岁)都有一定临床价值。     

双能X线和单光子吸收法及定量超声诊断骨质疏松症的比较

了解三种方法诊断骨质疏松症（ＯＰ）之间的关系。方法应用双能Ｘ线吸收法（ＤＸＡ）和单光子吸收法（ＳＰＡ）及定量超声（ＱＵＳ），同时随机测量２９４例受试者腰椎后前位和侧位、左侧髓部和前臂骨矿密度（ＢＭＤ）及右侧胫骨超声速度（ＳＯＳ）。结果ＤＸＡ和ＳＰＡ测量桡骨ＯＰ的检出率分别为２５．９％和２１．４％，ＤＸＡ测量腰椎后前位、侧位、侧位兴趣区、Ｗａｒｄ’ｓ区和股骨颈ＯＰ检出率分别为１６．０％、２２．８％、２６．２％、１９．４％和４．４２％，ＱＵＳ的ＯＰ检出率为１７．７％。三种方法及不同部位之间的测量结果呈显著相关（ｒ＝０．４９４～０．９６７，Ｐ＜０．０１）。ＤＸＡ测量前臂１／３处ＢＭＤ显著高于ＳＰＡ。诊断ＯＰ的齐同率ＤＸＡ各部位相互之间平均为４０．１％±１５．５％，ＤＸＡ与ＳＰＡ平均为４８．４％±１９．０％，ＱＵＳ与ＤＸＡ和ＳＰＡ平均为３８．８％±１０．２％，各平均值之间无显著差异。结论ＯＰ的检出率取决于受检部位，腰椎侧位兴趣区和挠骨是检出率最高的部位，股骨颈和尺骨是最低的部位。ＳＰＡ与ＤＸＡ测量前臂ＢＭＤ高度相关，诊断结果无显著性差别。     

双能X线吸收法骨密度测定

骨质疏松作为老年人的常见病之一 ,越来越受到社会各界的关注。骨密度测量是明确骨质疏松的诊断、估计骨质疏松的程度、评价骨质疏松的疗效[1 ] 的必要手段。随着骨密度测量技术的发展 ,越来越多的精确度和准确度越来越高的骨密度测量方法问世。双能Ｘ线吸收法 (ＤＸＡ)以其准确度和精确度高、辐射剂量低、扫描时间短、调节稳定等优点广泛地应用于临床[2 ] 。本文就ＤＸＡ测定方法有关内容进行综述 ,供广大临床工作者参考。ＤＸＡ的工作原理ＤＸＡ用Ｘ线管代替同位素产生独立的双能量光子 ,通过单独测量这两种能量光子的吸收情况 ,计算出骨…     

两种双能X线吸收法骨密度仪测量骨块模型的精密度和灵敏度比较

目的　了解扇形束 (HologicQDR 450 0A)和笔形束 (LunarDPX IQ)DXA骨密度仪测量结果之间的关系 ,探讨两者的数据换算关系。方法　 1 6个骨块模型分别在HologicQDR 450 0A型和Lu narDPX IQ型DEXA仪上测量 3次 ,比较两者的灵敏度。选取其中 3个骨块模型连续测量 2 0次求变异系数 ,比较两仪器的批内精密度。每天测 5次连续 2 0d求变异系数 ,比较两仪器的批间精密度。人体腰椎骨块模型每天测 5次连续 8d,建立两仪器之间数据换算关系。结果　 (1 )LunarDPX IQ型DEXA仪的灵敏度高于HologicQDR 450 0A型DEXA仪。 (2 )用小动物软件测量BA、BMC、BMD ,HologicDEXA仪的批内精密度分别为 0 57%、0 8%、1 1 % ;LunarDPX IQ型DEXA仪分别为 2 2 %、1 0 0 %、1 0 4%。HologicDEXA仪的批间精密度分别为 1 2 %、2 8%、2 4% ;LunarDPX IQ型DEXA仪分别为2 0 %、1 0 3 %、1 0 5 %。结果均显示HologicDEXA仪的精密度高于LunarDEXA仪。 (3)两仪器之间的BA、BMC、BMD绝对值差异明显 (P <0 0 5) ,但可用线性回归方程进行数据换算 :①BMD :Hologic值 =0 80 2×Lunar值 +0 31 8(r=0 991 ;P <0 0 0 1 ;SEE =0 0 3g/cm2 ) ;②BMC :Hologic值 =1 2 0×Lunar值 +1 685(r=0 984;P <0 0 0 1 ;SEE =0 81 6g) ;③BA     

应用双能X线骨密度仪探讨糖尿病性骨质疏松症的影响因素

目的探讨2型糖尿病患者骨质疏松的影响因素。方法选择2011年9月至2013年3月在内分泌科住院的男性2型糖尿病患者209例为糖尿病组,选择同期体检的健康男性103例为对照组,应用双能X线骨密度仪(DXA)进行正位腰椎(L1-L4)及左侧股骨骨密度(BMD)测定,检测糖化血红蛋白(Hb A1C)、空腹血糖(FPG)及空腹C肽(CP),并进行统计学分析。结果糖尿病组骨量减少、骨质疏松发生率分别为14.35%、13.87%,明显高于对照组(P0.05)。两组检测者随着年龄增加,骨密度均呈下降趋势,50岁以上糖尿病患者腰椎及股骨颈骨密度均明显低于同龄对照组(P0.05)。糖尿病组骨密度多因素相关性分析显示,糖尿病患者骨密度与年龄、病程、Hb A1C呈显著负相关(P0.05),而与体重指数(BMI)、空腹C肽(CP)呈显著正相关(P0.05)。结论 2型糖尿病患者骨量减少及骨质疏松发生率较健康体检者明显升高;高龄、病程长及血糖控制不良是糖尿病患者BMD降低的危险因素。     

双能X线骨密度仪测定83例2型糖尿病人骨密度分析

目的 了解2型糖尿病患腰椎及髋部骨矿物密度的变化。方法 双能X线骨密度仪测定2型糖尿病病人共83例(年龄40—79岁)，其中男性43例，女性40例；健康对照组71例(年龄40—79岁)，男性38例，女性33例。对比分析糖尿病组与同性别同龄正常组的测量结果，另根据病程将糖尿病组分为大于5年及小于5年组，并对2组结果进行分析。结果①糖尿病组与健康对照组比较，腰椎及髋部骨密度差异无显性；②病程大于5年与小于5年的2型糖尿病患间骨密度差异无显性。结论 2型糖尿病是否引起骨矿物密度降低或增高有待进一步研究。     

应用双能X线骨密度仪对辽宁地区正常人群骨密度的流行病学调查

目的 调查辽宁地区正常人群骨密度值及骨质疏松患病率，为骨质疏松的预防提供科学依据。方法 对辽宁地区一般人群随机抽样2300例，应用美国Lunar公司生产的双能X线骨密度仪分别测试受试的L2－4及股骨上段（包括股骨颈，Ward's区及粗隆部位）的BMD值。结果 各检测组的BMD峰值均出现于20－29岁组，且BMD随年龄增加而逐渐降低，进入50－59岁组，女性的骨量丢失速度明显加快，尤以Ward's区明显。60－69岁年龄组的骨质疏松症患病率，男性为27％，女性为46．8％。结论 BMD随年龄增长而下降，骨质疏松发病率也随之增加，女性发病率明显高于男性。     

An evaluation of dual-energy X-ray absorptiometry and comparison with dual-photon absorptiometry

Dual-photon absorptiometry (DPA) is a well-established procedure for measuring bone mineral density (BMD). Recently, dual-energy X-ray absorptiomery (DXA) has become available, which has the ability to measure BMD both regionally and in the total body (TB). We have evaluated the in vivo and in vitro precision of a DXA instrument and compared it with a DPA instrument with similar software characteristics.The short-term precision of BMD measurements using DXA was assessed in 65 postmenopausal women who had duplicate scans performed, with repositioning between scans. Precision was 0.9% in the lumbar spine and 1.4% in the femoral neck.The midterm precision of DXA was compared with DPA by scanning 10 volunteers a mean of four times over 24 weeks, on both instruments. The precision of the bone mineral content (BMC) and area measurements was significantly better (P<0.05) with DXA than with DPA. Long-term in vitro precision was assessed by scanning an aluminium spine phantom over 42 weeks, and a cadaveric sample over 52 weeks, on both instruments. Precision was similar using the aluminium phantom, but was significantly improved (P<0.001) when using DXA for scanning the cadaveric sample.Highly significant correlations (allP<0.001) of BMD, BMC and area measurements were observed when 70 volunteers were scanned on both instruments. However, there was a systematic difference in BMD values between the instruments. The precision of TB composition measurements assessed in 16 volunteers, over a 16-week period, were TB BMD 0.65%, TB lean tissue 1.47%, and TB fat tissue 2.73%. The correlation between weight measured by electronic scales and TB mass as measured by DXA, which was assessed in 70 volunteers, was excellent (r=0.99,p<0.001).We conclude that DXA offers improvements in measuring BMD over DPA in terms of faster scanning times and improved resolution, resulting in better precision, with the additional advantage of the ability to measure TB composition with high precision.     

Precision and stability of dual-energy X-ray absorptiometry measurements

Summary This study was performed to determine the precision and stability of dual-energy X-ray absorptiometry (DEXA) measurements, to compare bone mineral density (BMD) of subjects measured by DEXA and radionuclide dual-photon absorptiometry (DPA), and to evaluate different absorber materials for use with an external standard. Short-term precision (% coefficient of variation, CV) was determined in 6 subjects scanned six times each with repositioning, initially and 9 months later. Mean CV was 1.04% for spine and 2.13% for femoral neck BMD; for whole-body measurements in 5 subjects, mean CV was 0.64% for BMD, 2.2% for fat, and 1.05% for lean body mass. Precision of aluminum phantom measurements made over a 9-month period was 0.89% with the phantom in 15.2 cm, 0.88% in 20.3 cm, and 1.42% in 27.9 cm of water. In 51 subjects, BMD by DEXA and DPA was correlated for the spine (r=0.98,P=0.000) and femoral neck (r=0.91,P=0.000). Spine BMD was 4.5% lower and femoral neck BMD 3.1% higher by DEXA than by DPA. An aluminum phantom was scanned repeatedly, in both water and in an oil/water (30∶70) mixture at thicknesses ranging from 15.2 through 27.9 cm. Phantom BMD was lower at 15.2 cm than at higher thicknesses of both water and oil/water (P=0.05, ANOVA). The phantom was scanned repeatedly in 15.2, 20.3, and 27.9 cm of water over a 9 month period. In 15.2 and 20.3 cm of water, phantom BMD did not vary significantly whereas in 27.9 cm of water (equivalent to a human over 30 cm thick), phantom BMD increased 2.3% (P=0.01) over the 9 months.     

Spurious dual-energy X-ray absorptiometry images in a patient exposed to the contrast agent thorotrast

A 69-year-old woman presented with a 20-year history of back pain and a 10 cm height loss. She had received an injection of the contrast agent, Thorotrast, at age 23. There was no history of fluoride exposure. Multiple vertebral compression fractures were seen on radiographs. Dual-energy X-ray absorptiometry (DXA) scans revealed high normal bone mineral content on the spine and, on whole body scan, visualization of the liver and spleen regions. Given the attenuation coefficient of thorium and the thorium concentrations reported for liver, spleen and vertebral bodies, it is likely that thorium was visualized in the liver and spleen and that it caused spurious elevation in her DXA bone mineral content values.     

The geographic availability and associated utilization of dual-energy X-ray absorptiometry (DXA) testing among older persons in the United States

Summary  Using national Medicare data from 1999–2006, we evaluated the relationship between travel distance and receipt of dual-energy X-ray absorptiometry (DXA). After adjusting for potentially confounding factors, travel distance was strongly associated with DXA testing. Rural residents were most strongly dependent on the availability of DXAs performed in physician offices. Introduction  Medicare reimbursement for DXAs performed in non-facility settings (e.g., physician offices) decreased in 2007. With declining reimbursement, some DXA providers may cease providing this service, which would increase travel distance for some people. The impact of travel distance on access to DXA is unclear. Methods  Using national Medicare data, we identified claims for DXA to evaluate trends in the number and locations of DXAs performed. Travel distance was the distance from beneficiaries’ residence and the nearest DXA provider. Binomial regression evaluated the relationship between travel distance and receipt of DXA. Results  In 2006, 2.9 million DXAs were performed, a 103% increase since 1999. In 2005–2006, 8.0% of persons were tested at non-facility sites versus 4.2% at facility sites. The remainder (88%) had no DXA. Persons traveling 5–9, 10–24, 25–39, and 40–54, and ≥55 miles were less likely to receive DXA (adjusted risk ratios = 0.92, 0.79, 0.43, 0.32, and 0.26, respectively, <5 miles referent). Rural residents were more dependent than urban residents on the availability of DXA from non-facility providers. Conclusion  Approximately two-thirds of DXAs in 2005–2006 were performed in non-facility settings (e.g., physician offices). Rural residents would have preferentially reduced access to DXA if there were fewer non-facility sites.     

Optimizing data acquisition and analysis of morphometric X-ray absorptiometry

Morphometric X-ray absorptiometry (MXA) uses dual-energy X-ray absorptiometry (DXA) scanners to perform vertebral morphometric measurements of the vertebrae. In this study we evaluated the four available MXA scan modes - single-energy (SE) and dual-energy fast (F), array (A) and high definition (HD) - on a commercial bone densitometer (Hologic QDR-4500A). Sixty postmenopausal women (mean age 59 years, range 40–73 years) were recruited and split into two groups matched for body mass index (BMI, kg/m²). Three MXA scans, covering 13 vertebrae from T4 to L4, were acquired on each subject; all subjects were scanned in SE and A modes, while the third scan was performed in F mode in group 1 and in HD mode in group 2. Subjects were invited to return 6 months after the commencement of the study to repeat their scans. The HD mode produced the most reliable image, with 97% of all scans analyzable to T7 and the fewest vertebrae being lost to analysis (1.5/13 vertebrae lost per scan). A SE + HD combination (using whichever image allows the analysis of more vertebrae) further decreased the number of vertebrae lost to 0.8 of 13 vertebrae, i.e. a typical scan was analyzable up to and including T5. BMI had a noticeable and scan-mode-dependent effect on MXA image quality, an increase in the number of vertebrae lost to analysis occurring once BMI exceeded 30. BMD had a far smaller effect on image quality and no effect at all using the SE+HD combination. Precision (CV%) was similar for all three dual-energy modes at around 3.5% without the scan ‘compare’ facility and 2.6% with it. The best precision was obtained with SE scan (2.7%/2.2%). BMI and BMD had little or no effect on precision. We conclude that optimal results are obtained by the acquisition of both SE and HD scans. However, for rapid assessment by trained operators SE scans alone offer almost equal utility.     

Precision and accuracy of in vivo bone mineral measurement in rats using dual-energy X-ray absorptiometry

The aim of this study was to evaluate the precision and accuracy of dual-energy X-ray absorptiometry (DXA) for measuring bone mineral content at different sites of the skeleton in rats. In vitro the reproducibility error was very small (<1%), but in vivo the intra-observer variability ranged from 0.9% to 6.0%. Several factors have been shown to affect in vivo reproducibility: the reproducibility was better when the results were expressed as bone mineral density (BMD) rather than bone mineral content (BMC), intra-observer variability was better than the inter-observer variability, and a higher error was observed for the tibia compared with that for vertebrae and femur. The accuracy of measurement at the femur and tibia was assessed by comparing the values with ash weight and with biochemically determined calcium content. The correlation coefficients (R) between the in vitro BMC and the dry weight or the calcium content were higher than 0.99 for both the femur and the tibia. SEE ranged between 0.0 g (ash weight) and 2.0 mg (Ca content). Using in vitro BMC, ash weight could be estimated with an accuracy error close to 0 and calcium content with an error ranging between 0.82% and 6.80%. TheR values obtained between the in vivo and in vitro BMC were 0.98 and 0.97 respectively for femur and tibia, with SEE of 0.04 and 0.02 g respectively. In conclusion, the in vivo precision of the technique was found to be too low. To be of practical use it is important in the design of experimentation to try to reduce the measurement error. This can be achieved by performing measurements in the same position, by repeating measurements several times and by using the mean values of several BMD calculations performed by the same observer on each BMD measurement. Furthermore, better reproducibility can be obtained on the vertebra or the femur than on the tibia.     

Dual-energy X-ray absorptiometry in normal women: A cross-sectional study of 717 finnish volunteers

The bone mineral density (BMD) of the lumbar spine and proximal femur was measured using dual-energy X-ray absorptiometry in 717 healthy women aged 20–70 years. The maximal mean BMD was found at the age of 35–39 years in the spine and at the age of 20–24 in the femoral neck and Ward's triangle. No significant change in lumbar BMD was found from the age of 20 to 39 years. The spinal BMD values were relatively stable from age 20 to 39 years, whereas a linear decrease in BMD in the femoral neck and Ward's triangle was already apparent in the youngest age group (20–24 years). The major fall in BMD in all sites was related to the menopause. The overall decreases in BMD from the peak values to those at age 65–70 years were 20.4%, 19.0% and 32.6% in the lumbar spine, femoral neck and Ward's triangle, respectively. The correlation of trochanteric BMD with age was poor. BMD was positively correlated with weight in all measurement sites. Nulliparity was found to be a risk factor for osteoporosis. The present study confirmed that the menopause has a significant effect not only on spinal BMD but also on femoral BMD. Lumbar BMD was lower and BMDs in the proximal femur were higher in Finnish women than in white American women. This emphasizes the importance of national reference values for BMD measurements.     

Accuracy and precision of lumbar bone mineral content by dual-energy X-ray absorptiometry in live female monkeys

Summary Dual-energy X-ray absorptiometry (DXA) was used to determine thein vivo bone mineral content (BMC) of lumbar vertebrae in 20 feral adult female cynomolgus macaques (Macaca fascicularis). The ash weight of the third lumbar vertebra (L3) was compared to the measured L3BMC of thein vivo DXA analyses. Correlation between the estimated L3BMC by DXA and the actual ash weight was significant (r=0.965,P<0.01); however, DXA methodology underestimated ash weight on the average of 6.2%. Correlation was significant between two sequentialin vivo DXA scans (r=0.988,P<0.001). Noninvasivein vivo DXA was a fast, precise, and effective method for measuring the lumbar BMC in female cynomolgus macaques.     

体重体成分与骨密度的关系

为了研究体成分与骨密度（ＢＭＤ）之间的关系，因体重与ＢＭＤ显著相关，体成分各个组成相加等于体重，而体成分与ＢＭＤ的关系仍不清楚。方法随机选取２０６名１６～５２岁健康的男女性汉族人，用双能Ｘ射线吸收法（ＤＸＡ）测量ＢＭＤ与体成分，进行ＢＭＤ与体重，体成分的多元线性回归分析。结果体重，瘦组织（ＬＴＭ）与男女性的ＢＭＤ显著正相关，脂肪组织（ＦＴＭ）仅对女性全身，腰椎ＢＭＤ起显著性作用。结论影响男女性ＢＭＤ的体成分中，ＬＴＭ是主要因素，ＦＴＭ仅对女性ＢＭＤ有影响。本文较全面地研究了体成分与ＢＭＤ的关系。