双能X线骨密度仪测量不同条件椎骨的精度差异初探

目的 探讨DPX－MD双级X线骨密度仪测量腰椎铝体模，活体腰椎，死体腰椎（带软组织）骨密度（BMD）的短期精密度，以我骨密度检测质量控制和减少误差提供依据。方法 用DPX－MD骨密度仪测量铝体模和3个活体，1个死体腰椎标本，作短期精度研究。结果 变异系数铝体模最小，活体以骨密度正常是系数较骨密度异常小，死体最大，其L2－4变异系数各为0．131％，0．542％，1．033％和3．442％。结论 铝体模短期精度最好，活体以骨密度正常短期精度较骨密度异常好，死体最差。说明不同条件椎骨的精度存在差异。     

双能X线骨密度仪测量不同条件椎骨的精度差异初探

目的探讨DPX-MD双能X线骨密度仪测量腰椎铝体模、活体腰椎、死体腰椎(带软组织)骨密度(BMD)的短期精密度,以便为骨密度检测质量控制和减少误差提供依据。方法用DPX-MD骨密度仪测量铝体模和3个活体、1个死体腰椎标本,作短期精度研究。结果变异系数铝体模最小,活体以骨密度正常者变异系数较骨密度异常者小,死体最大,其L2～4变异系数各为0.131%、0.542%、1.033%、2.844%和3.442%。结论铝体模短期精度最好,活体以骨密度正常者短期精度较骨密度异常者好,死体最差。说明不同条件椎骨的精度存在差异。     

不同性别Singh指数与双能X射线骨密度仪测量骨密度的相关性

背景:Singh指数和骨密度测量是临床常用来了解骨强度及骨质疏松情况的方法,而二者之间的相关性及其性别差异性未见报道.目的:了解Singh指数与双能X射线骨密度仪测量骨密度在不同性别的相关性.方法:取股骨颈骨折行假体置换患者股骨颈标本42份,将42份标本按性别分组采用双能X射线骨密度仪测量体外股骨颈骨密度值;对术前X射线片进行Singh指数分级,了解Singh指数与骨密度的双变骨量相关性.结果与结论:男性Singh指数与骨密度的双变骨量相关性分析结果显示,Spearman相关指数r=0.646,P=0.002,二者有非常显著的相关性,并且男性骨密度值与Singh指数有正相关性,根据二者的检查结果可初步判断患者骨质疏松情况;女性Singh指数与骨密度的双变骨量相关性分析结果显示,Spearman相关指数r=0.304,P<0.181,二者无统计学上的相关性,说明女性患者因绝经后骨质疏松加剧,骨密度值与Singh指数相关性不明确,临床治疗时需根据个体情况采用不同治疗方法.     

双能X线骨密度仪与定量CT测量骨密度的比较

骨质疏松必须有症状、体征、实验室检查(骨代谢生化和激素指标等)，X线片等方法的帮助，特异的定量的诊断骨质疏松的手段是骨密度测量，没有骨密度的支持是不能诊断骨质疏松。有创的骨组织形态计量法的手段难于在临床上推广，目前广泛应用的是各种无创性骨密度测量手段。故而临床中骨密度的测定目前主要是双能X线骨密度仪(dual-X-ray absorptiometry，DXA)与定量CT，但DCA与定量CT测量骨密度的争论由来已久。文章拟从两者的测量方式、原理及临床运用中遇到的问题作一综述。     

双能X射线骨密度仪不同测量方式检测大鼠骨密度的准确性

背景:双能X射线骨密度仪是诊断骨质疏松症的金标准,但采用其系统默认方式测量小动物骨密度误差很大。目的:观察双能X射线骨密度仪不同测量方式对大鼠骨密度测量准确度的影响。方法:应用双能X射线骨密度仪对六七月龄雌性SD大鼠进行全身扫描,分别采用自定义手动矩形方式、手动椭圆形方式与系统默认标准方式依次测量大鼠的全身、头部及脊柱部位的骨密度。结果与结论:手动椭圆形方式与系统默认方式测得的大鼠全身、头部和脊柱的骨密度差异无显著性意义(P>0.05),而手动矩形方式与系统默认标准方式间差异有显著性意义(P<0.01)。双能X射线骨密度仪应用手动椭圆形方式与系统默认标准方式对测量结果影响不大,但手动矩形测量方式误差较大。提示手动椭圆形方式可作为小动物骨密度测量后的分析方法之一。     

双能X线骨密度仪在15cm水深中测量骨密度的准确性

目的：探讨双能X线骨密度仪(dual energy X-ray absorptiometry，DXA)测量骨密度的准确性。方法：用DXA(前后位扫描)测量5具浸泡在15cm水深中的猪腰段脊柱，共计20例椎骨，计算测量的结果与灰重及灰重密度相关性。结果：骨矿含量与灰重呈显著正相关性(r=0．95，P&;lt;0．01)，而骨密度与灰重无明显相关性(r=0．41，P&;gt;0．05)。结论：DXA测量骨密度中骨矿含量较准确，而骨密度较差。     

双能X射线骨密度仪测量离体羊股骨骨折端及钢板对接骨折端的骨密度

背景:目前,羊已逐渐成为骨质疏松研究中很有前途的动物模型。目的:采用双能X射线骨密度仪测量羊股部骨折断端及全部骨密度,探讨双能X射线骨密度仪测量过程中的准确度和精确度。方法:对双能X射线骨密度仪自带的Lunar腰椎模型扫描10次/d,确定机器准确度,再连续扫描25d,根据所测数据建立Shewhart控制图。选取3只羊中5根股骨进行7次重复扫描,采用骨密度仪自带的小动物分析软件分析羊股部骨折断端的骨密度、全部的骨密度,计算其精密度。另外选取4只羊8根股骨,用2种钢板对骨折断端固定,分析骨密度及骨矿含量的变化。结果与结论:双能X线骨密度仪的准确度为-1.0%,离体羊股部骨折断端及全部的骨密度测量精密度为0.005～0.537g/cm2。股骨全部骨和骨折断端密度的短期精密度分别为0.8%和1.5%,股骨全部和骨折断端骨矿物含量的短期精密度为0.9%和7.5%。不同钢板固定后的羊股骨骨密度、骨矿含量差异无显著性意义。结果证实,双能X射线骨密度仪能准确测量离体羊股骨的骨密度,但在骨折断端骨矿含量精密度分析有一定的误差。     

双能X射线骨密度仪测量离体羊股骨骨折端及钢板对接骨折端的骨密度

背景：目前,羊已逐渐成为骨质疏松研究中很有前途的动物模型。目的：采用双能X射线骨密度仪测量羊股部骨折断端及全部骨密度,探讨双能X射线骨密度仪测量过程中的准确度和精确度。方法：对双能X射线骨密度仪自带的Lunar腰椎模型扫描10次/d,确定机器准确度,再连续扫描25d,根据所测数据建立Shewhart控制图。选取3只羊中5根股骨进行7次重复扫描,采用骨密度仪自带的小动物分析软件分析羊股部骨折断端的骨密度、全部的骨密度,计算其精密度。另外选取4只羊8根股骨,用2种钢板对骨折断端固定,分析骨密度及骨矿含量的变化。结果与结论：双能X线骨密度仪的准确度为-1.0%,离体羊股部骨折断端及全部的骨密度测量精密度为0.005～0.537g/cm2。股骨全部骨和骨折断端密度的短期精密度分别为0.8%和1.5%,股骨全部和骨折断端骨矿物含量的短期精密度为0.9%和7.5%。不同钢板固定后的羊股骨骨密度、骨矿含量差异无显著性意义。结果证实,双能X射线骨密度仪能准确测量离体羊股骨的骨密度,但在骨折断端骨矿含量精密度分析有一定的误差。     

双能X线骨密度仪椎体骨密度测定骨质疏松症临床价值分析

目的:对骨质疏松症应用双能X线骨密度仪测定锥体骨密度的临床疗效展开分析。方法:选择我院2018年11月-2019年期间收治的80例骨质疏松患者作为研究对象,对所有患者均实施双能X线骨密度仪,测定不同年龄阶段椎体骨质疏松的情况。结果:不同年龄阶段骨质量测定的均值存在差异。根据骨密度的测定将其分为两个标准,骨密度≤x-2.0SD,骨密度≤x-2.5SD。经测定发现,所有患者的骨密度均不足x-2.0SD,其中65例骨密度不足。随着年龄的增长,骨质量均差的值越小。结论:对骨质疏松症应用双能X线骨密度仪测定锥体骨密度能够起到较高的临床应用价值,为临床治疗提供详细的数据,诊断价值较高。     

两种双能X射线吸收法骨密度仪数据共享:Challenger与Holigic仪器的交叉校正

背景：为达到数据共享的目的,不同厂家生产的双能X射线吸收骨密度仪需要进行仪器之间的校正。目的：利用峰值骨量的人群尝试确立Challenger与Holigic QDR4500型DXA之间的数据换算关系。设计、时间及地点：数据直线相关及回归分析实验,于2007-10在青岛海慈医院骨密度室完成。对象：25～35岁符合青岛地区峰值骨密度的健康成年女性30人。方法：受试者分别经法国DMS公司产的Challenger型扇形束X射线吸收骨密度仪和美国Hologic公司产的QDR-4500A型扇形束X射线吸收骨密度仪测得骨密度值。主要观察指标：通过直线相关与回归分析分别计算出L2～4正位和左侧股骨颈、大转子、Ward三角区6个骨骼区域的骨密度换算公式,并进行青岛与长沙两地区健康女性多骨骼部位骨密度数据库校正前后的比较以验证公式的可行性。结果：两种骨密度仪测定得到的数据显著相关,存在线性关系。校正之前,青岛地区女性髋骨骨密度高于长沙地区;校正之后两地区骨密度无显著性差别。结论：峰值骨量人群可用于Challenger与Holigic QDR4500型双能X射线吸收骨密度仪之间的校正。     

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

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.     

Bone mineral density measured by dual-energy X-ray absorptiometry in normal men

A cross-sectional study of 222 healthy Finnish men aged 20-69 years was performed to establish reference values of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DEXA). The effects of age, and of some physical and lifestyle factors on BMD of the lumbar spine and proximal femur (femoral neck, Ward's triangle and trochanter) were investigated. The maximal mean BMD was observed at the age of 20-29 years in all the measurement sites. Except for the trochanteric area, BMD diminished along with age, the over-all decrements being 4%, 11%, and 23% in the lumbar, femoral neck and Ward's triangle areas, respectively. BMD was in a positive relationship to weight and height in all the measurement sites. The adjusted (for age, height and weight) BMDs were higher (P less than 0.05) in the group of daily dietary calcium intake greater than 1200 mg as compared with the group of lowest calcium intake (less than 800 mg day-1) in the three femoral areas. Cigarette smoking or alcohol drinking had no obvious effect on BMD.     

Validation of a body condition scoring system in rhesus macaques (Macaca mulatta): assessment of body composition by using dual-energy X-ray absorptiometry

Body condition scoring (BCS) is a subjective semiquantitative method of assessing body fat and muscle by palpation of key anatomic features. A previously published BCS system for rhesus macaques (Macaca mulatta) uses a scale comprising both whole and half units, in which the midrange represents optimal body condition (3.0), lower values represent emaciated to lean conditions (1.0 to 2.0), and higher values (4.0 to 5.0) indicate excessive body fat. A valid BCS system is well described, relevant to the species, has agreement within and between raters, and is consistent with objective measures. Here we correlate the subjective BCS assigned during physical exam with percentage body fat as determined by dual-energy X-ray absorptiometry (DEXA). Adult rhesus monkeys from an indoor-housed breeding colony were evaluated by the veterinary staff and assigned to 1 of 9 BCS score groups to give a minimum of 6 animals in each group. DEXA was used to obtain objective body composition measurements for macaques in each BCS group. Animals in the 'optimal' BCS group (3.0) had 25% body fat on average. Each full unit change in BCS was associated with an approximate 10% change in body fat percentage for macaques in the 2.0-to-5.0 BCS range. Absolute body fat in animals with BCS of 1.0 or 1.5 may be too low for accurate assessment by DEXA.     

Maximal respiratory pressures: Measurements at functional residual capacity in individuals with different health conditions using a digital manometer

BackgroundMeasuring maximal respiratory pressure is a widely used method of investigating the strength of inspiratory and expiratory muscles.ObjectivesTo compare inspiratory pressures obtained at functional residual capacity (FRC) with measures at residual volume (RV), and expiratory pressures obtained at FRC with measures at total lung capacity (TLC) in individuals with different health conditions: post-COVID-19, COPD, idiopathic pulmonary fibrosis (IPF), heart failure (CHF), and stroke; and to compare the mean differences between measurements at FRC and RV/TLC among the groups.MethodsInspiratory and expiratory pressures were obtained randomly at different lung volumes. Mixed factorial analysis of covariance with repeated measures was used to compare measurements at different lung volumes within and among groups.ResultsSeventy-five individuals were included in the final analyses (15 individuals with each health condition). Maximal inspiratory pressures at FRC were lower than RV [mean difference (95% CI): 11.3 (5.8, 16.8); 8.4 (2.3, 14.5); 11.1 (5.5, 16.7); 12.8 (7.1, 18.4); 8.0 (2.6, 13.4) for COVID-19, COPD, IPF, CHF, and stroke, respectively] and maximal expiratory pressures at FRC were lower than TLC [mean difference (95% CI): 51.9 (37.4, 55.5); 60.9 (44.2, 77.7); 62.9 (48.1, 77.8); 58.0 (43.9, 73.8); 57.2 (42.9, 71.6) for COVID-19, COPD, IPF, CHF, and stroke, respectively]. All mean differences were similar among groups.ConclusionAlthough inspiratory and expiratory pressures at FRC were lower than measures obtained at RV/TLC for the five groups of health conditions, the mean differences between measurements at different lung volumes were similar among groups, which raises the discussion about the influence of the viscoelastic properties of the lungs on maximal respiratory pressure.     

Measurement of myocardial extracellular volume using cardiac dual-energy computed tomography in patients with ischaemic cardiomyopathy: a comparison of different methods

The International Journal of Cardiovascular Imaging - To clarify the consistency and efficiency of four methods for myocardial extracellular volume (ECV) measurement (manual method using...     

Determination of creatine and guanidinoacetate by GC-MS: study of their stability in urine at different temperatures

ObjectivesEvaluation of a GC-MS method using N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) as the silylating agent for GC-MS. Study of the stability of creatine and guanidinoacetate in urine.Design and methods22 urines were kept at RT, 4 °C and ? 30 °C for 15 days.ResultsMTBSTFA produces a single chromatographic peak in contrast with other derivatizing agents. Creatine concentration increases at room temperature (326% on average), and at 4 °C (75%). However, detection decreases after freezing (? 37%). Guanidinoacetate is stable, but decreases after freezing (? 37%). Sonication before analysis is crucial to obtain repetitive results.ConclusionsA modified GC-MS method has been validated and the conditions for preservation of the urine have been established.     

双能X线吸收与定量CT对比评价北京地区中老年女性与年龄相关的骨丢失

目的 采用双能X线吸收(DXA)和定量CT(QCT)对比评价北京地区中老年女性骨密度与年龄相关的骨丢失。方法 收集北京地区接受腰椎正位及髋部DXA检查(面积骨密度测量)的社区女性10 472名,接受腰椎QCT检查(体积骨密度测量)的女性562名。将接受两种检查的受检者分别按每10岁年龄段分组。计算各组别的平均骨密度,并计算峰值骨密度各组别的骨丢失率,分析骨密度与年龄间的相关性。结果 DXA测量北京地区女性腰椎、股骨颈及全髋部的峰值骨密度均在30~39岁年龄组,40岁以后各部位骨密度开始不同程度减低,至80~94岁组腰椎、股骨颈、全髋部累计骨丢失率分别为21.7%、31.4%和29.5%;QCT测量腰椎松质骨的峰值骨密度在20~29岁组,至80~97岁组累计骨丢失率达58.2%。累计骨丢失率从高到低依次为腰椎松质骨 >股骨颈 >全髋部 >腰椎正位。结论 腰椎QCT可较DXA更早、更准确地显示中老年女性的骨丢失情况,对增龄性骨丢失更敏感。