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    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 61 (1997), S. 393-399 
    ISSN: 1432-0827
    Keywords: Key words: Bone mineral measurements — Dual X-ray absorptiometry — Weight change — Clinical trials.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Variation in soft tissue composition is a potential cause of error in dual X-ray absorptiometry (DXA) measurements of bone mineral density (BMD). We investigated the effect of patients' change of weight on DXA scans in 152 women enrolled in a 2-year trial of cyclical etidronate therapy. Scans of the spine, hip, and total body were performed at baseline, 1 and 2 years on a Hologic QDR-2000. The study was completed by 135 subjects (64 on etidronate, 71 on placebo). Results were expressed as the percentage change in BMD (spine, femoral neck, total body) or bone mineral content (BMC) (total body only) at 2 years. Total body scans were analyzed using the manufacturer's `standard' and `enhanced' algorithms. Analysis was performed using multivariate regression with percentage change in BMD or BMC as the dependent variable, and treatment group and percentage change in weight as the independent variables. Weight change varied between −14.4% and +16.7%. All DXA variables showed a statistically significant treatment effect. Standard total body BMD and BMC and enhanced total body BMC all showed a significant dependence on weight change (P 〈 0.01, P 〈 0.001 and P 〈 0.01, respectively). No effect of weight change was seen on spine, femoral neck, or enhanced total body BMD. In order to investigate the effects of weight on long-term precision, patients were allocated to two groups according to baseline body mass index (BMI 〈25 and 〉25 kg/m2, respectively). For femoral neck BMD the root mean square (RMS) residual percentage change was statistically significantly larger in the high BMI group (P 〈 0.05) but all other bone density variables showed no significant difference. With patients allocated to two groups according to their absolute percentage change in weight (〈5% and 〉5%, respectively) the RMS residual percentage changes in the bone density variables were statistically significantly larger in the large weight change group for femoral neck BMD (P 〈 0.05) and for standard and enhanced total body BMC (P 〈 0.01 and P 〈 0.05, respectively). With the exception of the standard total body algorithm, weight change in a longitudinal study of postmenopausal women was not found to cause systematic errors in the results of DXA studies but may adversely affect precision.
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  • 3
    ISSN: 1432-0827
    Keywords: Key words: Cyclical etidronate therapy — Treatment withdrawal — Bone mineral measurements.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The objective of this study was to evaluate whether the pharmacological activity of cyclical etidronate therapy is sustained beyond the dosing period. A group of 121 postmenopausal women who had completed a 2-year, double-blind, placebo-controlled parallel study with etidronate or placebo (400 mg/day for 14 days every 3 months) and calcium agreed to participate in a 1-year open-label follow-up study to evaluate the effect of discontinuing etidronate treatment. Fifty-nine subjects in the former etidronate group and 62 in the placebo group received 500 mg/day of elemental calcium; 54/59 and 58/62 subjects, respectively, completed the study. Outcomes of the study were bone mineral density (BMD), measured by dual energy X-ray absorptiometry (DXA), and biochemical markers of bone turnover (urinary deoxypyridinoline/creatinine and serum osteocalcin). To determine whether there was a residual effect of previous therapy we compared mean percentage changes from baseline (year 0) to year 3 for both spinal and femoral neck BMD and markers of bone turnover in the former cyclical etidronate and placebo groups. To evaluate the carryover effect of treatment we compared the percent change from year 2 to year 3 for the same variables. Mean percentage change (SEM) from year 2 to year 3 for spinal BMD in the former cyclical etidronate group was −2.87% (0.48%) versus −0.99% (0.36%) in the placebo group (P= 0.0022). In the femoral neck, the BMD changes were −0.86% (0.42%) versus −1.01% (0.41%) (NS). Biochemical markers increased within 6 months toward baseline levels. Mean percentage changes from baseline (year 0) in both spinal and femoral neck BMD were significantly different between groups 1 year after treatment discontinuation. No differences between groups were maintained in deoxypyridinoline and osteocalcin. It is concluded that following withdrawal of cyclical etidronate therapy bone loss resumes at a normal and moderately accelerated rate in the proximal femur and lumbar spine, respectively. A positive effect on BMD at both cortical and trabecular sites is maintained for 1 year after treatment withdrawal.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 52 (1993), S. 263-268 
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Bone density ; Postmenopausal ; Vertebral collapse ; Bisphosphonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bone mineral density (BMD) at the lumbar spine, femoral neck, trochanteric region, and Ward's triangle was measured using dual-energy X-ray absorptiometry (DXA) in 118 women with osteoporotic vertebral collapse (average age 65 years), divided into four groups according to numbers and SD of vertebral deformation below norms: group 1:-3SD deformations only; group 2: one-4SD deformation; group 3: two-four-4SD deformations; and group 4: 5 or more-4SD deformations. There were no significant differences between the groups. Results were compared with those from 80 premenopausal (average age 32 years, range 20–40 years) and 109 postmenopausal normal women (average age 64, range 60–70 years). Mean BMD in osteoporotic group 1 was lower than premenopausal normal women by 32% at the lumbar spine, 31% femoral neck, 30% trochanteric region, and 44% at Ward's triangle, and postmenopausal controls by 17% lumbar spine, 16% femoral neck, 17% trochanter, and 14% Ward's triangle. There was a clear trend to reduction in mean BMD between osteoporotic groups 1 and 4 at all four measured sites with significant differences at the spine of 0.102 g/cm2 (P〈0.01) and Ward's triangle 0.059 g/cm2 (P〈0.01). When compared with premenopausal controls, there was a reduction in mean BMD between osteoporotic groups 1 and 4 of 10% at the lumbar spine, 7% femoral neck, 8% trochanteric region, and 13% Ward's triangle. Receiver operating characteristic analysis showed no significant differences in diagnostic sensitivities among the four measured sites for vertebral fractures. We conclude from this crosssectional data that the majority of bone loss in spinal osteoporosis occurs before the onset of fractures.
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  • 5
    ISSN: 1432-0827
    Keywords: Postmenopausal women ; Lumbar vertebrae ; Trabecular organization ; Macroradiography ; Fractal signature analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract High definition macroradiography was used to provide an image of the detailed structural organization of the cancellous bone in human lumbar vertebrae. The fractal signature analysis (FSA) method was used to quantify the horizontal and vertical trabecular organization recorded within the image. Comparison of the FSA of the posteroanterior and lateral macroradiographs in postmortem lumbar vertebrae showed that neither the superimposition of the neural arch nor the radiographic angle affected the trabecular measurement within the vertebral body. FSA analysis of the trabecular structure measured from the macroradiographs of lumbar vertebrae in two groups of postmenopausal women, with high and low bone mineral density (BMD), showed that the large vertical trabecular structures correlated with the women's body weight (P〈0.01–0.03) and body mass index (P〈0.005–0.05), the fine horizontal structures correlated with the women's age (P〈0.005–0.05), and fine vertical trabecular structures were significantly greater (P〈0.005–0.05) in the low compared with the high BMD group.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 56 (1995), S. 210-214 
    ISSN: 1432-0827
    Keywords: Bone mineral measurements ; Dual x-ray absorptiometry ; Volumetric bone density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0827
    Keywords: Bone mineral measurements ; Broadband ultrasonic attenuation ; Calcaneus ; Ultrasonic velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Measurements of broadband ultrasonic attenuation (BUA) and velocity of ultrasound through the heel (heel velocity, HV) were performed with a Contact Ultrasonic Bone Analyzer (CUBA-Research model) in 229 women. The subjects consisted of 16 healthy young volunteers (Group 1, mean age 26 years), 170 healthy pre- and postmenopausal women (Group 2, mean age 53 years), and 43 osteoporotic women with radiographically defined vertebral crush fracture (Group 3, mean age 66 years). Subjects in Group 1 had 10 repeated measurements in a study of short-term precision. Women in Groups 2 and 3 also had dual X-ray absorptiometry (DXA) scans to measure lumbar spine and femoral neck bone mineral density (BMD). The BUA and HV measurements for all 229 women showed a significant correlation (r = 0.75,P 〈 0.001). The precision study on the subjects in Group 1 gave a root mean square coefficient of variation of 6.3% for BUA and 1.04% for HV. Linear regression analysis gave the following relationship between BUA and age for the 170 normal women in Group 2: BUA = 83.6 − 0.86 (age 40) dB/MHz (r = −0.31,P 〈 0.001, SEE = 16.3 dB/MHz). The relationship between HV and age was as follows: HV = 1614 − 2.3 (age 40) m/s (r = −0.33,P 〈 0.001, SEE = 42 m/s). Multivariate regression analysis showed that in addition to age, years since the menopause was also a significant factor in determining both BUA and HV. In the first 5 years following the menopause, BUA and HV decreased by 2.2% and 0.3%/year, respectively, whereas in the next 10 years the rates of decrease fell to 0.5% and 0.03%/year. The BUA and HV measurements on the 43 osteoporotic subjects in Group 3 gave mean T-scores of −2.1 and −1.9 compared with 59 premenopausal women, and mean Z-scores of −1.3 and −0.9 compared with 26 age-matched normal women in Group 2, respectively. In comparison, the lumbar spine and femoral neck DXA measurements in the same subjects gave mean T-scores of −2.9 and −2.1 and mean Z-scores of −1.7 and −1.0, respectively. Lumbar spine BMD gave the best discrimination between women with osteoporotic vertebral fractures and normal subjects. However, the difference between the lumbar spine and BUA Z-scores was not statistically significant. Femoral neck BMD was equivalent to the ultrasound parameters in T-score and Z-score values.
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