Quantification of bone mineral contents using dual photon absorptiometry in a normal Japanese population — total body bone mineral

We established reference values for total body bone mineral of normal Japanese subjects utilizing dual photon absorptiometry. The index of measurement, total body bone mineral content (TBBM) divided by lean body mass (LBM), might be suitable for the evaluation of total body bone mineral. TBBM/LBM did not correlate with age in male subjects; however, reduced bone mineral was noted in female subjects after fifth decade. The rate of change in bone after the fifth decade was 0.82% per year. The bone mineral density (BMD) of each region including total body also showed a significant decrease with aging in women after the age of 40. Again no significant age-related changes were obtained in male BMD of any region (head, trunk, pelvis, legs, arms). The annual loss in women after the bone loss began was 0.72% in total body BMD. The rate of BMD change in each region of bone after 40 years of age ranged from 0.91% (trunk) to 0.51% (arms) per year. The bone mineral content (BMC) in “trunk” portion of TBBM decreased significantly with aging, while BMC of other portions did not show a significant age-related change. These results differ slightly from results which we have already reported for lumbar spine BMD, in which case average annual rates of bone loss once begun, were 0.32% for male and 0.97% for female.     

Comparative assessment of bone mineral density of the forearm using single photon and dual X-ray absorptiometry

Summary Forearm bone mineral density (BMD) was measured at proximal and distal sites by ¹²⁵I single photon absorptiometry (SPA) and by dual energy X-ray absorptiometry (DXA) in 67 consecutive subjects, aged 18–75 years. Correlations and regression equations between these two techniques were determined. All forearm measurements were significantly correlated with each other (r=0.599–0.926; P0.0001). Although SPA and DXA correct for fat in different ways, we found similar correlation and regression equations in women with body mass index measurements above and below the mean. In addition, forearm measurements by both techniques were moderately correlated with vertebral spine and hip BMD. We conclude that overall, SPA forearm measurements in a population can be calibrated to DXA measurements if necessary, and that DXA forearm measurements are as predictive of the remainder of the skeleton as SPA measurements.     

A comparison of quantitative dual-energy radiographic absorptiometry and dual photon absorptiometry of the lumbar spine in postmenopausal women

Summary Noninvasive bone densitometry is an important aspect in the detection and management of osteoporosis and other forms of metabolic disease of calcified tissue. A system using quantitative dual-energy digital projection radiography (QDR) of the lumbar spine was systematically tested against dual-photon absorptiometry (DPA) of the lumbar spine in 131 women over 55 years of age and free from major risk factors for osteoporosis. All subjects were scanned by both QDR and DPA under the same conditions. Measurements for a given subject were made within 15 minutes of each other. Bone mineral densities (BMD) were determined for four individual levels in the lumbar spine (L1-L4). Regression equations for BMD vs. age, height, and weight were calculated. The results of this investigation indicate that DPA- and QDR-derived BMD values are comparable. BMD values derived by QDR were consistently lower than those obtained by DPA (DPA=1.115 QDR+0.137, r=0.942). The L2 lumbar region was the most strongly correlated determination.     

Determination of bone mineral density by dual x-ray absorptiometry in patients with uncemented total hip arthroplasty.

Bone remodeling is an expected sequela with total hip arthroplasty (THA). Although there are several methods of estimating bone response in THA patients from radiographs, there are no accurate and generally accepted methods for quantitative determinations in vivo. In this study, we describe an application of dual x-ray absorptiometry (DXA) for measuring bone mineral content and bone mineral density in the proximal femur following THA. DXA is a noninvasive technique with minimal radiation exposure (< 5 mrem). Various aspects of measurement error (accuracy and reliability) of this application of DXA were determined in a series of studies reported here. Accuracy error (how similar are the measured and actual values) was < 1% determined in bone phantoms of four densities. Precision error (how reproducible are the measurements) was also < 1% at all four densities in the phantoms and was only slightly elevated (0.9-1.5%) in repeated measurements of implanted cadaver femora. Precision error in vivo, determined both from multiple replicates on five patients and from duplicate scans on 30 patients, was further elevated but remained < 5%. Contributions to precision error, rotation of the leg, and interoperator variability were assessed; none was found to elevate precision error appreciably. We suggest that DXA is a feasible method for quantifying bone response following THA, and will allow discrimination of small changes (> 5%) not previously measurable.     

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.     

体重和身长对大白鼠骨量影响的双能X线吸收法的应用

体重、体组成指数和其它因子对双能X-线吸收法(DXA)测量的骨密度(BMD)和骨矿物质音量(BMC)的影响巳经在人体上被广泛研究。然而它们对大白鼠骨量的影响仍未见报道．为此．秘们应用DXA仪测量了雌性Wistar大鼠全身骨密度和全身骨矿物质含量以及腰椎骨密度和腰椎骨矿物质音量．61其大鼠(体重范围220g～300g)的测定结果表明：体重明显相关于全身骨矿物质含量（r=0．835，P=0.0001)、全身骨密度(r=0．561，P=0．0001)、腰椎骨矿物质含量(r=0．681，P=0．0001)和腰椎骨密度(r=0.531，P=0．0001)；身长也相关于上述指标，相关系数和P值分别为r=0．545，P=0．0001；r=0．371，P=0．0032；r=0．496，P=0．0001和r=0．289，P=0．024。为进一步调查体重对骨量的影响，我们将这些动物接体重分成3组，当二组之间的体重差在20g以上时，两组的骨量就显示了差异，在等身长条件下，体重明显相关于骨量；然而在等体重条件下，身长和骨量不相关。结果表明，体重和身长也影响大鼠骨量．也许前者施加的影响更明显。大鼠体重和身长明显相关于BMD，BMC的结果与人体情况是一致的。     

Normative values of lumbar spine mineral density and fracture threshold in Japanese measured by dual photon absorptiometry based on scinticamera methods (Dualomex HC-1)

Using a dual photon absorptiometer Dualomex HC-1 based on the scinticamera system utilizing¹⁵³Gd, bone density of the lumbar vertebrae was measured to set up normative values for each group in both sexes along with fracture threshold. Bone density of the lumbar spine was measured in 712 male and female subjects ranging in age between 16 and 96 years at 11 medical instructions all over Japan, to establish normative values for each age and sex group. The peak bone mass of 0.75 g/cm² was reached in the 30s in males and that of 0.76 g/cm² in the 40s in females. The lumbar spine density obtained by this method showed good parallelism with the Singh index and degree of lumbar spine bone loss according to Jikei University method. A high correlation was also found between the bone density obtained by this method and that obtained by Lunar DP-4 (r=0.902, n=28). Spinal compression fracture was found in about 2/3 of the subjects with L2 – L4 bone density measured in the anterior-posterior direction of less than 0.58 g/cm² and 3/4 of those with the corresponding value less than 0.49 g/cm². Bone density less than 0.49 g/cm² was therefore tentatively called the range predicting fracture (dangerous range) and that between 0.49 and 0.58 as the range warning fracture (warning range).     

The accuracy of volumetric bone density measurements in dual X-ray absorptiometry

New developments in dual x-ray absorptiometry (DXA) allow the performance of high precision anteroposterior (AP) and lateral scans of spinal bone mineral density (BMD, units: g/cm²) without the patient moving from the supine position. Data from both projections may be combined to give an estimate of the true volumetric bone mineral density (VBMD, units: g/cm³) of the lumbar vertebral bodies. This report presents a cadaver study designed to validate DXA measurements of volumetric bone density. Sections of whole lumbar spine were scanned in AP and lateral projections in a water tank to simulate soft tissue. Individual vertebrae were then divided to separate the vertebral body from the neural arch, and vertebral body volume was measured using the displacement of sand. The bone mineral content (BMC) of vertebral bodies and neural arches was measured by ashing at 250°C for 60 hours followed by 500°C for a further 24 hours. The results showed that DXA scanning systematically underestimated ashing data by 14% for AP BMC, 33% for vertebral body BMC, 23% for vertebral body volume, and 12% for VBMD. Despite these significant systematic errors, the DXA measurements and ashing values were highly correlated (r=0.979-0.992). The results suggested that after allowing for the systematic errors, lateral DXA parameters related closely to true BMC, volume, and VBMD.     

Vertebral and total body bone mineral content by dual photon absorptiometry

Conclusions Techniques have been developed using dual-photon absorptiometry for precise and accurate measurement of bone mineral content in the lower spine and in the total body. A spinal measurement requires only 20 min and a total body scan about 60 min. The dose from these measurements is very low allowing them to be repeated at frequent intervals. We feel these improved techniques will prove of great value both for examining the skeleton in normal populations and for evaluation of osteoporosis and other skeletal abnormalities.     

Effective dose values in bone mineral measurements by photon absorptiometry and computed tomography

A high degree of uncertainty and irritation predominates in the assessment and comparison of radiation dose values resulting from measurements of bone mineral density of the lumbar spine by photon absorptiometry and X-ray computed tomography. The skin dose values which are usually given in the literature are of limited relevance because the size of the irradiated volumes, the relative sensitivity of the affected organs and the radiation energies are not taken into account. The concept of effective dose, sometimes called whole-body equivalent dose, has to be applied. A detailed analysis results in an effective dose value of about 1 µSv for absorptiometry and about 30 µSv for computed tomography when low kV and mAs values are used. Lateral localizer radiographs, which are necessary for slice selection in CT, mean an additional dose of 30 µSv. Lateral X-ray films of the spine which are frequently taken in combination with absorptiometry result in a dose of 700 µSv or more. The concept of effective dose, the basic data and assumptions used in its assessment and a comparison with other dose burdens (for example the natural background radiation, of typically 2400 µSv per year) are discussed in detail.     

去卵巢对大鼠骨密度的影响

目的：探讨去卵巢对大鼠骨密度（BMD）的影响。方法；20只3．5月龄SD雌性大鼠分别除双侧卵巢（OVX）或假性去卵巢（Sham)，术后14周处死，应用QDR－4500A型扇形束双能X射线吸收法（DXA）测量大鼠全身、离体股骨、胫骨、腰维及兴趣区的BMD。结果：①术后6周OVX组全身BMD显低Sham组（P＝0．048），术后14周两组无显性差异；②术后14周OVX组离体股骨BMD显低于Sham组（P＜0．01），股骨远侧干骺端平均降低11．6％（P＜0．001）；③术后14周右侧离体胫骨BMD两组间差异无显性，但OVX组胫骨的端干骺端BMD显低于Sham组（P＜0．001）；④术后14周OVX组腰椎（L4－L6）的BMD显低于Sham组（P＝0．014），第六腰椎降低明显，平均降低8．1％（P＝0．005）。结论：去卵巢所致骨丢失以松质骨含量丰富的兴趣区明显。     

In vitro comparability of dual energy X-ray absorptiometry (DEXA) bone densitometers

Summary Six Hologic QDR-1000 DEXA bone densitometers at different centers across the USA were compared to determine the intermachine variability. Nine scans in succession were acquired on each machine using a single anthropomorphic lumbar spine phantom (manufactured by Hologic). Values for BMC, area, and BMD were recorded for each measurement. Means, standard deviations (SD), and coefficients of variation (CV) were calculated for each machine. All the CVs (BMC, area, BMD) were less than 1% (range 0.3%–0.6%). The CV of the means at the six sites were 0.4%, 0.6%, and 0.5% for BMC, area, and BMD, respectively. Although several significant differences for BMC, area, and BMD were noted by ANOVA between machines at different sites, the difference between the highest and lowest means of the individual machines was only 1.1%, 1.31%, and 1.07% for BMC, area, and BMD. The small variations between the DEXA systems are encouraging for researchers involved in multicenter trials in which data are pooled.     

Fundamental evaluation of dual x-ray absorptiometry (DXA) for measurement of bone mineral density in rats

This study was designed to assess the precision and accuracy of newly developed ultra high resolution mode (rat mode) in DXA (Hologic, QDR-1000), determine how body thickness affects measured BMD values and to derive a formula by which BMDs in animals with varying degrees of body thickness can be compared. The long term reproducibility on two phantoms (BMD: 170 and 300 mg/cm²) were under CV 1.0%. The repeated precision in vivo and in vitro lumbar spines and phantoms were within CV 1.5%. Accuracy was evaluated by determining the correlation coefficient between ash weight and tibial BMC. The correlation was excellent (r=0.999, p<0.001) over the ash range of 250–600 mg. Using single regression equations, QDR-1000 BMC values were compared with those obtained by conventional methods. There was a close linear correlation with both SPA (Norland Co., r=0.997) and DCS-600 (Aloka Co., r=0.996) measurements. The effects of body thickness were assessed by immersing phantoms at various water depths. There was a significant linear decrease in BMD, as measured by QDR-1000, with increasing water depth. BMDs in vivo with varying body thickness can be compared with each other by using the following correcting formula: BMD₁=(BMD₂+5.5w+7.6) × 10³/(977-4.8w), where BMD₁=expected BMD of extracted bone (mg/cm²), BMD₂=BMD in vivo (mg/cm²), w=body thickness (cm). There was a significant positive correlation (r=0.996, p<0.001) between calculated BMDs from this equation and the values actually obtained. These results confirm that QDR-1000 rat mode yields data useful for assessing BMD and BMC in small animal bones.     

Lumbar vertebral bone mineral density in Japanese infants and children: Measurement with dual x-ray absorptiometry

Dual x-ray absorptiometry (DXA) (Hologic QDR-1000/W; Hologic, Inc.) was used to measure lumbar vertebral bone mineral density (BMD) in 83 healthy Japanese infants and children (55 boys and 28 girls) aged 0–17 years, and the values obtained were correlated with age, body weight and body height. The lumbar BMD (average of L1–L4 values) increased with age, with a nearly twofold increase found from preschool age to adolescence. It also increased with body weight and body height. Our results on normal Japanese infants and children appear almost similar to those reported in French and American studies. Because of its great precision and accuracy, low radiation exposure and rapid scanning, DXA may be the most suitable for use in infants and children. With normal Japanese data now available with this technique, pediatricians can better detect metabolic bone diseases in infants and children and follow the bone response to medical intervention in patients with these conditions.     

Changes in bone mineral density following total knee arthroplasty: a 1-year follow-up study by dual energy X-ray absorptiometry

The assessment of bone density by means of dual energy Xray absorptiometry is a valid option for monitoring bone changes. In this study, time-related bone changes after total knee arthroplasty implantation were assessed in eight postmenopausal women (aged 62–72 years) up to one year from surgery. The pattern of bone changes followed a well-known design: an initial phase of accelerated bone loss and a subsequent phase of partial bone recovery. The greatest bone loss was observed at 2 months after surgery: 5.0% for the whole periprosthetic bone in the AP projection and 11.5% for the bone in the LL projection. In the following ten months the bone loss in the AP projection was completely recovered while the periprosthetic bone evaluated in the LL projection showed a residual bone loss of 9.0%. At 12 months from surgery, the distal femur in LL projection showed the greatest bone loss: 20.0% for the anterior region of interest and 17.0% for the posterior one. A significant correlation was found between the maximum postoperative bone loss and the residual bone loss at 12 months. These results suggest that pharmacological and rehabilitative strategies may be useful for the conservation of bone stock. Received: 9 February 2002, Accepted: 12 February 2002 Correspondence to: C. Trevisn     

Nondestructive measurement of bone mineral in femurs from ovariectomized rats

Summary One hundred ninety-eight rats were ovariectomized (OX) or sham-ovariectomized (shOX) at 100 days of age. Groups were killed at 35, 70, 100, 125, 180, 270, 360, and 540 days postsurgery. Bone mineral content (BMC) of the right femur was assayed on a dual photon absorptiometer (DPA) optimized for human spine and whole body measurements. Three regions were studied: the distal measuring 0.8 cm, the proximal measuring 0.88 cm, and the diaphysis, the remainder. The DPA technique accurately showed the ash content (r=0.96), with a precision error of 3–5%. Whole femoral BMC was 4.3–11.1% lower in OX than shOX rats, with significant differences from 35–180 days. By 35 days, distal femoral BMC declined 6% in OX rats and rose 12% in shOX rats. Distal femoral BMC was 11.3–17.5% lower in OX than shOX rats, with significant differences at all times except 540 days. Femoral diaphyseal BMC of OX and shOX rats did not differ at any time. The relative distal femoral osteopenia which appeared by 35 days in OX rats did not worsen during the next 17 months. A DPA suited for human BMC studies is also accurate for BMC determination in bones with 250–500 mg of mineral It is less precise for this purpose than dedicated instruments using single photon absorptiometry. However, enough precision exists to monitor the development of relative osteopenia in OX rats. Osteopenia in OX rats is confined to a region containing appreciable cancellous bone. Its self-limiting nature suggests the existence of an estrogen-dependent quantum of cancellous bone in female rats. The adult rat model is accurate for cancellous bone of the adult human, but inaccuare for cortical bone.     

Bone mineral density measured by dual X-ray absorptiometry in Spanish patients with insulin-dependent diabetes mellitus

Previous studies suggest that low bone mass is a potential complication of insulin-dependent diabetes mellitus. Nevertheless, the factors that influence diabetic osteopenia are not well established. In order to evaluate the prevalence and magnitude of diabetic osteopenia and its association with clinical and metabolic variables, we studied 94 consecutive patients with insulin-dependent diabetes mellitus. Their age ranged from 20 to 56 years and duration of diabetes varied from 1 to 35 years. Bone mineral density (BMD) was measured by dual X-ray absorptiometry at lumbar spine and proximal femur and the values were expressed as z-score. The presence and extent of microvascular complications, degree of metabolic control, and other risk factors for osteoporosis were recorded and some biochemical markers of bone metabolism were assessed. Diabetic patients showed reduced BMD in all sites (lumbar spine: −0.89±1.21; femoral neck: −0.99±1.24; Ward triangle; −1.05±1.24;P<0.0001). Of the 94 patients 19.1% met diagnostic criteria for osteoporosis. BMD correlated with body mass index in all sites and with the duration of disease in Ward's triangle. Presence and extent of diabetic complications were associated with lower BMD, as was smoking. No correlation was found between BMD and biochemical markers. In conclusion, osteopenia is a common complication in patients with insulin-dependent diabetes mellitus. Microvascular complications are a critical point in the progression of diabetic osteopenia. Other risk factors for osteoporosis (nutritional status and smoking) must be taken into account. Preliminary results partially presented at the EASD Meeting in Prague, Czechoslovakia, September 1992     

DXA 髋结构分析参数预测髋部脆性骨折的价值

目的探讨双能X线吸收测量法(DXA)髋几何力学参数在预测髋部脆性骨折风险中的应用价值。方法髋部骨折女性患者41例(年龄52.3~89.4岁)及正常对照组259例(年龄28.2~88.3岁)行DXA扫描获取股骨颈骨密度(femur neck BMD,FN_BMD)及髋几何力学分析参数,包括股骨颈横截面惯性矩(CSMI)、股骨颈横截面面积(CSA)、截面模数(SM)、曲率比率(BR)、颈宽度(FNW)、髋轴长(HAL)、股骨颈干角(NSA),并计算股骨近端强度指数(FSI)。利用受试者工作特征曲线(ROC)分析相关变量判定髋部骨折的效能。结果校正年龄、身高、体重、BMI混杂因素,髋部骨折组与非骨折组间FN_BMD差异有显著性意义(P0.01),髋部骨折组FSI、SM、CSMI、CSA较非骨折组低(P均0.05),而BR、FNW、NSA、HAL较非骨折组高(P均0.05);当校正FN_BMD时,只有FSI、NSA及HAL在两组间差异仍有统计学意义(P均0.05)。控制混杂因素,FN_BMD与FSI(r=0.339)、BR(r=-0.291)、SM(r=0.644)、CSMI(r=0.425)、NSA(r=-0.291)呈轻-中度相关性,FN_BMD与CSA相关密切性最好(r=0.908,P0.001)。FN_BMD、FSI、HAL、NSA判定髋部骨折的ROC曲线下面积(AUC)分别为0.794±0.031、0.790±0.032、0.652±0.049、0.684±0.049。FN_BMD及FSI判定髋部骨折的效能相仿(P=0.9128)。FN_BMD联合FSI判定髋部骨折的AUC为0.844±0.039,较FN_BMD大(P0.05)。结论 FSI独立于FN_BMD起作用,可作为判断骨质疏松性髋部骨折的有用因子。FN_BMD联合FSI可以提高预测髋部骨折风险的能力。     

Vertebral bone mineral density measured laterally by dual-energy X-ray absorptiometry

The bone mineral density (BMD) of lumbar vertebrae in the anteroposterior (AP) view may be overestimated in osteoarthritis or with aortic calcification, which are common in elderly. Furthermore, the risk of spinal crush fracture should be more closely related inversely to the BMD of the vertebral body than to that of the posterior arch. Therefore, we measured BMD of lumbar vertebrae in lateral (LAT) view (L2–L3), using a standard dual-energy X-ray absorptiometer (DEXA), thus eliminating most of the posterior spinal elements. The precision of BMD LAT measurement was determined both in vitro and in healthy volunteers. Then, we compared the capability of BMD LAT and BMD AP scans for monitoring bone loss related to age and for discriminating the BMD of postmenopausal women with nontraumatic vertebral fractures from that of young subjects. In vitro, when a spine phantom was placed in lateral position in the middle of 26 cm of water in order to simulate both soft-tissue thickness and X-ray source remoteness, the coefficient of variation (CV) of six repeated determinations of BMD was 1.0%. In vivo, the CV of paired BMD LAT measurements obtained in 20 healthy volunteers after repositioning was 2.8%. The age-related difference between a peak bone mass group estimated in a group of 27 healthy women aged 20 to 35 years and a group of 50 women aged 60 to 75 years, in whom neither vertebral fracture nor osteoporosis risk factors could be detected, were 21.7% and 37.6% in AP and LAT view, respectively. An arbitrary BMD fracture threshold was defined in AP and LAT views as the 90th percentile of the BMD value of a group of 22 osteoporotic women with vertebral fractures. The distribution of BMD AP and LAT above and below this threshold in 169 consecutively screened women without vertebral fracture was then analysed. In both AP and LAT views, 39.1% and 31.3% had BMD values above and below this threshold, respectively. Of the remaining, 16.0% had a BMD below this threshold only in AP and 13.6% only in LAT view. Thus, if BMD LAT was a better reflection of vertebral body bone mass than BMD AP, and thereby a better predictor of the resistance to crush fracture, our results would suggest that only the use of the standard AP view could under- or overestimate spinal fracture risk in about 30% of women screened for osteoporosis. In conclusion, our results indicate that BMD measurement in lateral view is feasible with a standard DEXA instrument. This mode of scanning, besides overcoming artefacts due to osteoarthritis of the posterior arch and aortic calcifications, appears to provide a greater sensitivity for assessing bone mass loss of the vertebral body than the standard anteroposterior scan.