Prediction of Bone Loss Rate in Healthy Postmenopausal Women

Prevention of fractures is the only way to drastically reduce osteoporosis-related health expenditures. In order to optimize the cost/benefit ratio of a strategy of prevention, it is essential to identify, as early as possible, women who will develop fractures later in their life. Therefore, and since postmenopausal bone loss is an asymptomatic process, screening procedures should detect, at the time of the menopause, women whose postmenopausal bone loss is higher than the mean, and will, a couple of years later, exhibit a low mineral content and a subsequent high risk for fractures. For 3 years we have followed a cohort of 92 healthy women who had undergone menopause less than 36 months previously. By a multivariate discriminant analysis based on the differences in lumbar bone density, assessed by dual photon absorptiometry, and in a few routine biochemical parameters (serum phosphorus, estrone, androstenedione, and urine calcium) observed during the first 6 months of the study, we have been able to correctly predict the rate of spinal bone loss, observed at the end of the 3 years, in 76% of the subjects. All of the women who presented a bone loss higher than 10% over the 3 years were correctly isolated by our discriminant functions after 6 months of follow-up. We conclude that a measurement of lumbar bone mineral density coupled with a few routine biochemical determinations, repeated twice at a 6-month interval in healthy postmenopausal women, can isolate 100% of postmenopausal ``fast bone losers' with an overall specificity of 76%. Received: 22 December 1995 / Accepted: 23 September 1996     

Influence of Spondylopathy on Bone Densitometry Using Dual Energy X-Ray Absorptiometry

Spinal cord injury (SCI), as well as other neuromuscular disorders, not only results in osteopenia but also induces various patterns of osseous, articular, and soft tissue alterations. In the spinal column, a variety of abnormalities occur. To evaluate the magnitude of discrepancy of bone densitometry results caused by spondylopathy in SCI patients, we analyzed anteroposterior (AP) radiographs of the lumbar spine [obtained within 1 month of dual energy X-ray absorptiometry (DXA)] in 116 SCI patients for various manifestations of spondylopathy, and matched the result to each vertebral level (L1, 2, 3, 4). The dataset was stratified by individual vertebra (totally 463 vertebrae) as valid (no demonstrable other abnormal density on plain radiograph except osteopenia), abnormal without, and abnormal with hardware. The influence of spondylopathy on bone densitometry results was determined by the analysis of variance (ANOVA) and post hoc analysis. Our results showed that 227 (49%) vertebrae were abnormal. Significant elevation (15%, 15%, 18%, 20%; P < 0.001–P < 0.05) of bone mineral density (BMD; g/cm²) was observed at all levels (L1, 2, 3, 4, respectively), particularly at those abnormal vertebrae without hardware compared with valid (no other abnormal density on radiograph except osteopenia (Table 1). The L4 level was most severely affected. We concluded that in SCI patients, owing to various secondary progressive skeletal abnormalities, particularly neuropathic spondylopathy, can have strongly and significantly elevated vertebral bone densitometry results, which can obscure underlying osteoporosis, leading to misinterpretation and underestimation of fracture risk. DXA, although characterized by improving spatial resolution, cannot replace radiography in establishing the magnitude of this skeletal pathology. Therefore, determination of bone density in this region with corresponding plain radiographs is highly recommended. Received: 30 July 1996 / Accepted: 3 December 1996     

生脉饮中五味子醇甲的薄层分离技术与扫描定量法

本文将高效薄层色谱法和常规薄层色谱法的程序多次展开技术和小孔线形技术用于生脉饮中难分离物质五味子醇甲的分离研究。结果表明:常规薄层小孔线形分离技术具有实用、简便和快速的特点;生脉饮经乙醚萃取后,硅胶GF薄层分离,薄层扫描法测定五味子醇甲的回收率达99.4%。     

Prevention of postmenopausal bone loss by rectal calcitonin

A group (150) of healthy women, who had been menopausal for less than 5 years and who had never received any form of treatment to prevent bone loss were entered into a randomized, controlled study comprising three arms. They were randomly allocated to the double-blind administration of five suppositories per week containing either 100 IU of salmon calcitonin or a placebo, or to a group receiving a suppository containing 200 IU of salmon calcitonin three times per week. All women received 500 mg/day of calcium supplementation. After 12 months, bone mineral density (BMD) of the spine, measured by dual energy X-ray absorptiometry, decreased significantly (P<0.01) in the placebo group by 3.1% (SD: 3.6%) but did not change in the two calcitonin groups [+1.3% (3.5%) with 100 IU/day and +2.3% (4.0%) with 200 IU 3/week]. The differences in response between the placebo group and the two calcitonin groups were significant (P<0.05), but the difference between the two regimens of calcitonin administration was not. No differences appeared among the three groups for the response at the level of the hip. Evolution of biochemical markers reflecting bone turnover did not differ significantly among groups. Nearly 40% of the women withdrew prematurely because of local (rectal or intestinal) intolerance to repetitive suppositories, with a nonsignificantly different frequency in the placebo or calcitonin groups. We conclude that rectal calcitonin might be an interesting preventive approach against trabecular postmenopausal bone loss but that long-term acceptability of suppositories should be evaluated in view of each patient's sensibility or cultural background.     

The Tromsø Study: Artifacts in Forearm Bone Densitometry – Prevalence and Effects

Suboptimal performance of bone densitometer, operator and/or subject may cause artifacts of consequence both for individual patient management and research. The prevalence and effects of such artifacts are largely unknown in densitometry. A cross-sectional population-based study was carried out of artifacts in forearm bone densitometry with single X-ray Absorptiometry (SXA) of the nondominant hand (distal and ultradistal site). After the screening, all scans were reviewed for artifact detection and reanalysis. The effect on the bone mineral density (BMD) result was found by comparing artifactual scans with a reanalyzed version or with normal repeat scans. All women aged 50–74 years, all men aged 55–74 years and 5–10% samples of other age groups aged ≥25 years attending the fourth Troms? health study were invited to have bone densitometry. The response rate from the background population was 80% (n= 7948). Fourteen percent of subjects had a movement artifact at either the distal or ultradistal site. The individual BMD variation was twice as large in scans with a movement artifact (0.94%) compared with normal scans (0.58%) (p= 0.0027). The radial endplate was inaccurately detected in 74% of the scans. Reanalysis of these scans led to a mean 3.8% decrease in the BMD value and an increase in the prevalence of osteoporosis of 10%. Artifacts were thus common, and their effects were clinically relevant in forearm bone densitometry. Artifacts and their effects need to be characterized in other bone densitometry settings also. Received: 25 February 1999 / Accepted: 3 May 1999     

Axial and Total-Body Bone Densitometry Using a Narrow-Angle Fan-Beam

We assessed a new dual-energy bone densitometer, the PRODIGY, that uses a narrow-angle fan-beam (4.5°) oriented parallel to the longitudinal axis of the body (i.e., perpendicular to the usual orientation). High-resolution scans across the body can be stepped at 17 mm intervals. The energy-sensitive array detector uses cadmium zinc telluride, which allowed rapid photon counting. Spine and femur scans required 30 s, and total-body scans required 4–5 min; the dose was only 3.7 mrem and 0.04 mrem respectively, or about 5 to 10 times lower than conventional fan-beam densitometry. We found only a small influence of soft-tissue thickness on bone mineral density (BMD) results. There was also a small ( ± 1%) influence of height above the tabletop on BMD results. A software correction for object height allowed a first-order correction for the large magnification effects of position on bone mineral content (BMC) and area. Consequently, the results for BMC and area, as well as BMD, with PRODIGY corresponded closely to those obtained using the predecessor DPX densitometer, both in vitro and in vivo; there was a generally high correlation (r= 0.98–0.99) for BMD values. Spine and femur values for BMC, area and BMD averaged within 0.5% in vivo (n= 122), as did total-body BMC and BMD (n= 46). PRODIGY values for total-body lean tissue and fat also corresponded within 1% to DPX values. Regional and total-body BMD were measured with 0.5% precision in vitro and 1% precision in vivo. The new PRODIGY densitometer appears to combine the low dose and high accuracy of pencil-beam densitometry with the speed of fan-beam densitometers. Received: 2 April 1999 / Accepted: 27 July 1999     

Comparison between metacarpal bone measurements by computarized radiogrammetry and total body DEXA in normal and osteoporotic women

Summary We evaluated the precision of metacarpal radiogrammetry by computed radiography as a technique for bone mass measurement. Measurements obtained using this method were compared with densitometric measurements of total body bone mass using dual-energy X-ray absorptiometry.Our results showed that the coefficients of variation for radiogrammetric measurements were similar in 60 women with osteoporosis and in 100 normal women: 0.7% in both groups for external diameter of the second metacarpal, 2.41% in the normal women and 2.03% in the women with osteoporosis for internal diameter, and 2.3% and 2.4%, respectively, for cortical thickness. Except for external metacarpal diameter, which did not differ between normal and osteoporotic women, all the measurements were smaller in the women with osteoporosis (p<0.001). The correlation between metacarpal cortical thickness and total body bone mineral content was r²=0.462 in the women with osteoporosis, r²=0.476 in the controls, and r²=0.522 in the two groups combined (all p<0.001). There was a significant correlation (p<0.001) between cortical thickness and densitometric metacarpal measurements of both the diaphysis and epiphysis. These results confirm the value of radiogrammetry as a technique for quantitating bone mass under normal and pathological conditions. Additional advantages of the method are minimal radiation dose delivered, possibility for storing the image and data, and technical facility.     

用三次回归模型建立女性多骨骼部位骨密度参考数据库及其应用评价

目的　建立和评价诊断女性骨质疏松 (OP)的多骨骼部位骨密度 (BMD)参考数据库。方法用QDR 45 0 0A型扇形束DXA骨密度仪测量 2 70 2例 5～ 96岁女性参考人群和 14 71例女性OP患者腰椎前后位和仰卧侧位、髋部及前臂 3 8个骨骼区域的BMD ,用 8种回归模型拟合整个健康女性人群BMD随年龄的变化 ,找出最佳拟合模型的方程建立参考数据库 ,与仪器配置的“东方女性”参考数据库同时诊断14 71例女性患者 ,评价两种参考数据库对OP检出率的差异。结果　 3 8个骨骼区域BMD随年龄变化 ,用三次回归模型拟合程度均优于其他回归模型 ,拟合曲线的决定系数 (R2 )为 0 .3 6～ 0 .65 (P <0 .0 0 1)。建立的长沙女性参考数据库 ,对患者腰椎及髋部的OP检出率比“东方女性”参考数据库低 18.8%～ 3 3 .7% ,而对前臂的OP检出率则高 2 0 .4%和 2 3 .8%。两种参考数据库对OP检出率之间的差异均具有显著性 (P <0 .0 0 1)。结论　仪器配置的“东方女性”参考数据库不适合长沙地区女性诊断OP。本研究建立的女性参考数据库 ,不仅为湖南地区女性 ,而且也为中国南方地区女性诊断OP提供了可靠的参考标准。     

Visual grading of motion induced image degradation in high resolution peripheral computed tomography: impact of image quality on measures of bone density and micro-architecture

Motion artifacts are a common finding during high-resolution peripheral quantitative computed tomography (HR-pQCT) image acquisitions. To date it is not clear (i) when to repeat an acquisition, (ii) when to exclude a motion-degraded dataset post hoc, and (iii) how motion induced artifacts impact measures of trabecular and cortical parameters. In this study we present inter- and intra-observer reproducibility of a qualitative image quality grading score and report the prevalence of repeat acquisitions in our population. Finally the errors in bone density and micro-architectural parameters estimated from repeat acquisitions with and without motion degradation are presented. The relationship between these errors and the image quality grade is evaluated for each parameter. Repeat acquisitions performed due to operator-observed motion in the reconstructed image occurred for 22.7% of the exams (29.7% radius, 15.7% tibia). Of this subset, 88 exams with repeat acquisitions had at least one acquisition graded 1 (best quality). In this subset, the percent differences in bone density and micro-architecture measures tended to increase as the relative image quality decreased. Micro-architectural parameters were more sensitive to motion compared to geometric and densitometric parameters. These results provide estimates of the error in bone quality measures due to motion artifacts and provide an initial framework for developing standardized quality control criteria for cross-sectional and longitudinal HR-pQCT studies.