Dual photon absorptiometry of the proximal tibia

Summary Bone mineral content (BMC) and bone mineral density (BMD) of the proximal tibia were determined by dual photon absorptiometry on 44 women, aged 23–87 years. The area of the tibia measured was a 2.01 cm region immediately distal to the medial and lateral tuberosities. Values of BMC ranged between 5.09 and 14.57 g and BMD between 0.380 and 1.180 g/cm². Both tibial BMC and BMD declined with age and tibial BMD was significantly correlated with lumbar spine (r=0.70), femoral neck (r=0.73), and femoral trochanter (r=0.74). However, the large standard errors of estimate (SEE) (0.08–0.14 g/cm²) do not allow for reliable prediction in an individual of other skeletal sites by the tibia. Repeated measurements demonstrated that dual photon absorptiometry of the proximal tibia is a reliable measurement and may be a useful tool in the monitoring of therapeutic or intervention modalities in those individuals with skeletal diseases in whom measurement of the lumbar spine or proximal femur may not be possible.     

体重标准化骨矿含量及应用前景

放射线测量骨矿的原始数据是骨矿含量(bone mineral content,BMC)。由于该值与骨大小和(或)体重成正比,因而用骨投影面积、骨体积和体重标准化BMC以消除它们的影响,分别称为面积骨密度、体积骨密度和体重标准化BMC(BMC/体重)。用面积骨密度诊断骨质疏松,易造成漏诊和误诊;体积骨密度可消除骨大小的影响,但整体骨体积尚难于在活体中获得;体重标化BMC,数据易获得,且在应用中初步表现出其优越性,可能在骨质疏松诊断应用中有较好的前景。     

The Effect of Peritoneal Dialysate on DXA Bone Densitometry Results in Patients with End-Stage Renal Disease

The bone mineral density of patients undergoing peritoneal dialysis (PD) is low compared to a healthy population. No studies have been conducted to investigate whether the presence of peritoneal dialysate affects dual-energy X-ray absorptiometry (DXA) results. We hypothesized that the presence of peritoneal dialysate would not affect the measurement of bone mineral density (BMD) or bone mineral content (BMC) in the spine. Thirty patients on PD had DXA scans of the lumbar spine and hip completed before and after the drainage of peritoneal dialysate. A paired t-test was used to compare the difference in area, BMC, and BMD before and after drainage of dialysate. A significant difference was found in the BMC of the spine before and after the drainage of dialyzate. We recommend that peritoneal dialyzate be removed prior to scanning patients on PD and that densitometry technologists should be observant about the presence of peritoneal dialysate.     

北京城区10?12岁女孩骨密度的研究

目的 观察10－12岁女孩骨密度（BMD）的变化。方法 对375例健康女孩行全身扫描和左前臂扫描，按首位（10岁）平均体重指数（BMI）分组为超重组（BMMI＞19．6）、正常组（BMI＝14．2－19．6）、偏轻组（BMI＜14．2）。1年和2年后，利用同台双能X线骨密度仪再次扫描，连续3年追踪观察该年龄段女孩每年BMD的变化。结果 全身各部位的BMD值和全身总的骨矿含量（BMC）值第2年明显高于第1年（P＜0．01－0．001）。第3年（12岁）与第2年（11岁）相比：仅前臂远端1／10处BMD值有明显增加（P＜0．001），前臂远端1／3处BMD值和全身总的BMD值无增加，且全身总的BMD值略有下降（P＞0．05）；但全身总的BMC值有明显增加（P＜0．001）。BMD、BMC值均以超重组最高，正常组次之，偏轻组最低。结论 青春期女孩不同部位的BMD值年增长率快慢不一，但全身总的BMC值总是随着年龄增长而增加。     

葛根素对绝经后骨质疏松大鼠不同部位骨骼的抗骨质疏松作用差异的研究

目的本文拟通过动物实验研究葛根素对大鼠骨密度的影响，探讨葛根素对不同部位骨骼抗骨质疏松作用的差异。 方法对24只雌性SD大鼠行双侧卵巢切除术，构建大鼠绝经后骨质疏松模型。采用葛根素处理大鼠后，分别于第2、4、8、12周采用双能X射线吸收法（DXA）检测其各部位骨骼骨密度随时间发生的变化，并对比不同部位骨骼骨密度、骨矿含量的差异，同时通过组织切片观察葛根素对骨组织微结构的影响。 结果葛根素应用后的第8周疗效最为显著，经葛根素处理后股骨远端、腰椎等松质骨的骨密度、骨矿含量显著提高，且骨小梁更粗、数量更多，而股骨中段等皮质骨的骨密度、骨矿含量变化则不大。 结论葛根素对绝经后骨质疏松大鼠松质骨的抗骨质疏松作用优于皮质骨。     

Proximal femur bone mineral levels of US adults

This paper describes bone mineral levels in the proximal femur of US adults based on a nationally representative sample of 7116 men and women aged 20 years and older. The data were collected in phase 1 of the third National Health and Nutrition Examination Survey (NHANES III, 1988–1991) using dual-energy X-ray absorptiometry, and included bone mineral density (BMD), bone mineral content (BMC) and area of bone scanned in five selected regions of interest (ROI) in the proximal femur: femur neck, trochanter, intertrochanter, Ward's triangle and total. These variables are provided separately by age and sex for non-Hispanic whites (NHW), non-Hispanic blacks (NHB) and Mexican Americans (MA). BMD and BMC in the five ROI tended to decline with age, whereas area did not. BMD and BMC were highest in NHB, intermediate in MA and lowest in NHW, but areas were highest in NHW, intermediate in NHB and lowest in MA. Men had greater BMD, BMC and area than women in all three race/ethnic groups. Differences by age, sex or race/ethnicity tended to be the largest in Ward's triangle, followed by the femur neck; patterns in the trochanter, intertrochanter and total ROI were reasonably similar to each other. This report provides extensive data on femur bone mineral levels of adults from one of the largest samples available to date and should be valuable as reference data for other studies which examine this skeletal site in adults.     

中药骨康对去势大鼠骨矿含量和骨密度的影响

本实验旨在观察骨康口服液对通过切除卵巢诱发的绝经后骨质疏松症大鼠模型骨矿含量(BMC)和骨密度(BMD)的影响。通过双能X线扫描．结果显示：给药3个月时骨康组大鼠胫骨干骺端处的BMC和BMD显著高于造模组;骨康高、低剂量组与阳性对照组无显著差异。提示骨康和尼尔雌醇均可显著提高去势大鼠胫骨干骺端处的BMC和BMD．二者作用相当,且BMC和BMD的变化较一致。     

用骨强度概念探索骨密度测量的诊断指标

30多年来，医学上一直用骨矿密度（BMD,g/cm^2）诊断骨质疏松，骨质疏松引起骨折，骨折由骨强度减低引起，体重是骨强度的重要决定因素。 本引入体重评价BMC（g）和BMD两个指标。结果，体重与BMC的相关明显强于与BMD的相关，证明男女之间的BMC差由体重引起，男女间相同体重配对的BMC没有差异，所以在评价骨的 力学强度上体重标准化后BMC优于BMC指标。     

A comparison of two dual-energy X-ray absorptiometry systems for spinal bone mineral measurement

Summary Two dual-energy X-ray absorptiometry (DEXA) systems—the Hologic QDR-1000 and the Norland XR-26 bone densitometers—were evaluated in terms of precision, accuracy, linearity of response, X-ray exposure, and correlation of in vivo spinal measurements. In vitro precision and accuracy studies were performed using the Hologic anthropomorphic spine phantom; linearity of response was determined with increasing thicknesses of aluminum slabs and concentrations of Tums E-X in a constant-level water bath. Both systems were comparable in precision, achieving coefficients of variation (CVs) of less than 1% in bone mineral content (BMC, g), bone area (cm²), and bone mineral density (BMD, g/cm²). Both were accurate in their determination of BMC, bone area, and BMD with reference to the Hologic spine phantom. Both systems also showed good BMC and BMD linearity of response. Measured X-ray skin surface exposures for the Hologic and the Norland systems were 3.11 and 3.02 mR, respectively. In vivo spinal measurements (n=65) on the systems were highly correlated (BMC: r=0.993, SEE=1.770 g; area: r=0.984, SEE=1.713 cm²; BMD: r=0.990, SEE=0.028 g/cm²). In conclusion, both systems are comparable in terms of precision, accuracy, linearity of response, and exposure efficiency.     

糖皮质激素对成年大鼠骨量的影响

目的利用双能X线吸收法(DXA)探讨成年大鼠接受糖皮质激素后骨量变化的规律。方法 21只44周龄SD雌性大鼠分别假性去卵巢+未注射糖皮质激素(SHAM组)、摘除双侧卵巢(OVX组)或注射甲基强的松龙[2.5 mg/(kg·d)](PRED组),应用扇形束DXA(QDR-4500A)每4周测定一次全身骨密度(BMD)、骨矿含量(BMC)、骨骼面积(AREA);术后12周处死,测定离体腰椎、股骨、胫骨及其兴趣区的BMD、BMC、AREA。压缩试验测定第二腰椎最大载荷和弹性模量。结果 (1)术后8周开始OVX组体重显著重于同龄SHAM组(8周时,P0.05,12周时P0.01),术后4周开始PRED组体重显著轻于同龄SHAM组(P0.05);(2)术后12周OVX组整体BMC显著高于SHAM组(P0.05),术后8、12周OVX组整体BMC显著高于PRED组(P0.05);(3)术后12周OVX组离体第5、6腰椎BMD及第6腰椎BMC显著低于SHAM组和PRED组(P0.05),PRED组离体各腰椎BMD、BMC、AREA与SHAM组无明显差异;(4)术后12周与SHAM组比较,OVX组离体股骨(-7.42%)、股骨远端(-10.85%)和近端(-6.92%)、胫骨近端(-11.40%)BMD显著降低(P0.05),其中股骨、股骨远端、胫骨近端BMC也显著降低(P0.05);(5)术后12周与SHAM组比较,PRED组离体股骨及各区BMD、BMC、AREA无显著性差异,整体胫骨及各区BMD无显著性差异;(6)术后12周与SHAM组比较,OVX组及PRED组胫骨中远端骨量增加;(7)与SHAM组比较,OVX组最大载荷和弹性模量显著降低,PRED组最大载荷显著降低。结论成熟期大鼠接受甲基强的松龙后,皮质骨和松质骨骨量没有显著变化,DXA检查难以发现其骨丢失情况;力学性能改变提示糖皮质激素更多的是引起骨质量的改变而导致了力学性能的下降及骨折的发生。     

Apparent bone mineral density estimated from DXA in healthy men and women

The aim of this study was to measure bone mineral density (BMD) in healthy people and examine the influence of age, anthropometry, and postmenopause on calculated bone mineral apparent density (BMAD). The study included 541 healthy subjects (249 men and 292 women), aged 20 to 79 years. Anthropometric measurements included height, weight, and body mass index (BMI). Bone mineral content (BMC) and areal BMD were measured at the lumbar spine and proximal femur, using dual-energy X-ray absorptiometry (DXA). The calculation of volumetric density relied on the formula BMAD=BMD/BA (where BA = bone area). Association between densitometric parameters and age, height, weight, and postmenopause was analyzed with multiple regression. BMC and BMD decreased with age, especially in postmenopausal women. The average annual bone loss in spine was 0.2% in both sexes, whereas femur loss was 0.5% in men and 0.3% in women. Bone area slightly increased with age in both sexes, and BMD loss after the age of 50 could be attributed to bone area increase. To minimize the effect of bone size on bone density, volumetric density and areal density were regressed to age, anthropometry, and postmenopause. Age and postmenopause were significantly associated with BMD and BMAD in the spine and femur. Furthermore, BMD showed a stronger association with height and weight than BMAD, in both regions. Weaker association of body height and weight with BMAD than with BMD suggests that BMD depends on the bone size and body size and that the different BMDs could be the consequence of the difference in those parameters.     

Interpretation of whole body dual energy X-ray absorptiometry measures in children: comparison with peripheral quantitative computed tomography

The assessment of bone health in children requires strategies to minimize the confounding effects of bone size on dual energy X-ray absorptiometry (DXA) areal bone mineral density (BMD) results. Cortical bone composes 80% of the total skeletal bone mass. The objective of this study was to develop analytic strategies for the assessment of whole body DXA that describe the biomechanical characteristics of cortical bone across a wide range of body sizes using peripheral quantitative computed tomography (pQCT) measures of cortical geometry, density (mg/mm³), and strength as the gold standard. Whole body DXA (Hologic QDR 4500) and pQCT (Stratec XCT-2000) of the tibia diaphysis were completed in 150 healthy children 6–21 years of age. To assess DXA and pQCT measures relative to age, body size, and bone size, gender-specific regression models were used to establish z scores for DXA bone mineral content (BMC) for age, areal BMD for age, bone area for height, bone area for lean mass, BMC for height, BMC for lean mass, and BMC for bone area; and for pQCT, bone cross-sectional area (CSA) for tibia length and bone strength (stress-strain index, SSI) for tibia length. DXA bone area for height and BMC for height were both strongly and positively associated with pQCT CSA for length and with SSI for length (all P < 0.0001), suggesting that decreases in DXA bone area for height or DXA BMC for height represent narrower bones with less resistance to bending. DXA BMC for age (P < 0.01) and areal BMD (P < 0.05) for age were moderately correlated with strength. Neither DXA bone area for lean mass nor BMC for lean mass correlated with pQCT CSA for length or SSI for length. DXA BMC for bone area was weakly associated with pQCT SSI for length, in females only. Therefore, normalizing whole body DXA bone area for height and BMC for height provided the best measures of bone dimensions and strength. DXA BMC normalized for bone area and lean mass were poor indicators of bone strength.     

High parity is associated with increased bone size and strength

Some, but not all, studies report an association between decreased hip fracture risk and high parity despite similar bone mineral density (BMD). Our hypothesis was that bone size, a major determinant of bone strength, is greater in women with high parity compared with low parity or nulliparous women. A cross-sectional study of 168 Hutterite women aged 40–80 years was conducted. BMD, bone mineral content (BMC) and bone area of the total body (TB), hip, femoral neck (FN), and lumbar spine (LS) were measured, as well as bone geometry at the 4% and 20% distal radius and bending strength at 20% radius. Diet and activity recall and strength measurements were obtained. Of the 168 women, 42 (25%) were nulliparous while the remaining women reported 1 to 16 births (median=6). Of the 126 parous women, 122 (97%) breast-fed their infants (range 1.5–24 months). Hip, FN and LS BMD were not associated with either parity or months of breast-feeding. TB BMC and bone area (both, p <0.05) and FN bone area ( p <0.01) were associated with parity. FN bone area was 4% greater in women with 7+ vs 1–4 children. Torsional bending strength, which includes structural and material bone properties, at the 20% distal radius was greater with higher parity ( p =0.01). No bone measure was associated with average months of breast-feeding. High parity is associated with increased radial torsional bending strength and femoral neck size. The greater femoral neck size, without higher BMD, may explain the reduced hip fracture risk among women with high parity previously reported in some studies.     

体重、身高对成都地区青壮年腰椎、髋部骨量的影响

目的　研究体重、身高对青壮年腰椎、髋部骨量的影响。方法　随机抽取成都地区年龄在 2 0～ 39岁 ,排除心肝肺肾、内分泌等慢性病、骨代谢疾病及脊椎畸形者 2 37名 (其中男性 10 8名 ,女性 12 9名 ) ,采用美国Lunar公司生产DPX L型双能X线骨密度仪测定受试者腰椎和髋部的骨矿含量 (BMC)、面积 (AREA)、骨密度 (BMD)。全部资料输入微机 ,用SPSS软件进行统计学处理。结果　体重、身高、体重指数 (BMI)与腰椎、髋部的BMC、Area、BMD呈正相关 ,其中体重与腰椎、髋部的BMC、Area中等程度相关 (r=0 39～ 0 5 5 ,P <0 0 1) ,身高与腰椎 (L2 - 4)AREA相关性最好 (r=0 75 8,P <0 0 1) ,体重、身高与BMD相关性差 (r=0 15 2～ 0 2 2 5 ,P <0 0 5 )。男性腰椎及髋部的BMC、AREA均明显高于同年龄组女性 (P <0 0 1) ,男、女L2 - 4BMD无显著性差异 (P >0 0 5 ) ,男性略低于女性。L2 - 4BMC与体重比值及L2 - 4AREA与体重比值 ,男、女无显著性差异 (P >0 0 5 )。L2 - 4Area与身高比值男性明显高于女性 (P <0 0 1)。结论　体重对青壮年BMC的影响大于身高 ,身高对L2 - 4AREA影响最大 ,男、女体重、身高的差异决定了峰值骨量的差异。BMC、Area、BMD 3项指标中 ,BMC更能反映体重、身高的差异 ,用BMC诊断骨质疏松     

Body size from birth to adulthood and bone mineral content and density at 31 years of age: results from the northern Finland 1966 birth cohort study

The purpose of this study was to evaluate the association between body size from birth to adulthood and bone mineral content (BMC) and bone mineral density (BMD) at the age of 31 years in a longitudinal study of the Northern Finland birth cohort for 1966. Data were collected at birth, 1, 14, and 31 years. This analysis was restricted to a subsample of individuals ( n =1,099) for whom the BMC (g) and BMD measurements (g/cm²) were performed on the distal and ultradistal radius by dual-energy X-ray absorptiometry (DXA) at the age of 31 years. Determinants of low BMC and BMD were analyzed using multivariate logistic regression. Growth retardation at birth, being underweight (BMI 20.0 kg/m²) at 31 years, and having a low calcium intake at 31 years were associated independently with low BMD at 31 years. Additionally, the proportion of subjects with low BMD was higher among those who had low standardized body weight (<1 SD) both at birth and at 14 years, and both at 14 and 31 years. Body weight at 31 years was the strongest associating factor of BCM at 31 years. Growth retardation at birth has long-lasting effects on adult bone mineral content and density of the distal and ultradistal radius independently of later body size, although adult body weight seems to be a most important determinant of BMC at the age of 31 years. Thinness and a low calcium intake are associated with low bone mineral content and density at 31 years of age. Further studies are needed to evaluate if these groups are at increased risk of osteoporosis in old age.     

骨密度测量评价股骨头无菌坏死的应用研究

目的探讨骨密度测量在评估股骨头无菌坏死病情程度和治疗效果中的应用价值。方法运用NORLAND EXCELL双能骨密度测量仪对临床筛选的128例正常人，47例股骨头无菌坏死的患者进行骨密度测量，测量数据包括骨密度值（BMD）、骨矿含量（BMC），对异常组治疗前后的BMD和BMC进行对比研究。结果44例股骨头无菌坏死患者的BMD、BMC较正常人减低（P〈0．05），经治疗后患者BMD、BMC均有升高。结论通过骨密度值的分析比较，BMD与股骨头无菌坏死程度具有显著相关性，通过骨密度测量可间接反映临床治疗效果。     

Osteoclastogenesis Inhibitory Factor/Osteoprotegerin Reduced Bone Loss Induced by Mechanical Unloading

Skeletal unloading resulting from space flight and prolonged immobilization causes bone loss. Such bone loss ostensibly results from a rapid increase in bone resorption and subsequent sustained reduction in bone formation, but this mechanism remains unclear. Osteoclastogenesis inhibitory factor/osteoprotegerin (OCIF/OPG) is a recently identified potent inhibitor of osteoclast formation. We studied effects of OPG administration on tail-suspended growing rats to explore the therapeutic potential of OPG in the treatment and prevention of bone loss during mechanical unloading, such as that which occurs during space flight. Treatment with OPG in tail suspension increased the total bone mineral content (BMC g) of the tibia and femur and the total bone mineral density (BMD g/cm²) of the tibia. Moreover, treatment with OPG prevented reduction not only of BMC and BMD, but also of bone strength occurring through femoral diaphysis. Treatment with OPG in tail-suspended rats improved BMC, BMD and bone strength to levels of normally loaded rats treated with vehicle. Treatment with OPG in normally loaded rats significantly decreased urinary excretion of deoxypyridinoline, but the effect of OPG in tail suspension was unclear. These results indicate that OPG may be useful in inhibiting bone loss-engendered mechanical unloading.     

Single X-ray absorptiometry of the forearm: Precision,correlation, and reference data

The performance of a single X-ray absorptiometry (SXA) device incorporating an X-ray tube as a photon source was evaluated with respect to precision in vivo and in vitro, scan time, image quality, and correlation with an existing dual energy X-ray absorptiometry (DXA) device. SXA precision in vivo, expressed as a coefficient of variation (CV), was 0.66% for bone mineral content (BMC) and 1.05% for bone mineral density (BMD). Precision in vitro, based on 78 BMC measurements of a forearm phantom over 195 days, was 0.53%. Correlation with DXA at the 8 mm distal forearm site was high (r=0.97 for BMC and r=0.96 for BMD). A preliminary SXA reference database composed of 151 healthy Caucasian American women was developed to facilitate the interpretation of patient measurements. SXA scan time was 4 minutes and delivered a radiation exposure of 1.68 mrem. SXA image quality and spatial resolution were superior to SPA and comparable to DXA.     

绝经后肥胖女性骨密度与血管内皮功能的关系研究

目的 探讨绝经后肥胖女性中骨密度(BMD)与血管内皮功能的相关性.方法 选择自然绝经1～5年的单纯肥胖者(体重指数≥25kg/m2),年龄40～55岁,按照双能X线检测结果选择正常骨量组39例,骨量减少组37例和骨质疏松组19例.所有受试者测定体脂、BMD、骨矿含量(BMC)和血管内皮功能,包括血流介导的内皮依赖性血管舒张(EDD)和硝酸甘油介导的非内皮依赖性血管舒张.结果 骨质疏松组平均年龄和平均绝经时间显著高于正常骨量组和骨量减少组(P<0.05或P<0.01).骨质疏松组及骨量减少组BMD和BMC均显著低于正常骨量组(P<0.05或P<0.01).骨质疏松组EDD显著低于正常体重组和骨量减少组(分别为5.45±2.99、7.76±3.70和7.32±3.41,均P<0.05).相关分析显示各部位的BMD、BMC均与EDD相关(P<0.05和P<0.01).结论 肥胖女性绝经后骨质疏松与血管内皮功能异常有关,对绝经后肥胖女性低骨量人群干预治疗可能有助于防治动脉硬化及心血管疾病.     

Dual Energy X-Ray Absorptiometry in Small Rats with Low Bone Mineral Density

The feasibility of dual energy X-ray absorptiometry (DXA) using the Norland XR-26 Mark II bone densitometer for measurements of bone mineral content (BMC) and bone mineral density (BMD) in small rats was evaluated. Thirty-two young, isogenic, Lewis rats (weights from 119 g to 227 g) were used; normal rats (n = 7) and rats with low BMD obtained from three different vitamin D-depleted models (n = 25). DXA measurements were performed using the special software for small animals. Duplicate scans of excised femurs performed at 2 mm/second (pixel size of 0.5 mm × 0.5 mm) were very precise measurements with a coefficient of variation (CV) below 1.6% in animals with normal BMD; in rats with low BMD, the CV was significantly higher (P= 0.02–0.04), 7.8% and 4.4% for BMC and BMD, respectively. Regression analysis demonstrated that these measurements were related to the ash weight (R² > 98.6%). The CV for measurements of the lumbar spine at 10 mm/second (pixel size 0.5 mm × 0.5 mm) was 2.6% and 2.2% for BMC and BMD, respectively in rats with normal BMD, and again higher (P= 0.03–0.14) in rats with low BMD, 7.3% and 4.7%, respectively, for BMC and BMD. Even though low CVs were obtained for total body duplicate scans (scan speed of 20 mm/second and a pixel size of 1.5 mm × 1.5 mm), the measurements were problematic for accuracy because of an overestimation of both BMC and the area of bone. Using these scan parameters the measurements of total body bone mineral could not be recommended in small rats with low BMD. Received: 21 May 1999 / Accepted: 3 August 2000 / Online publication: 22 December 2000