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D Felsenberg

Publications and source records attributed to D Felsenberg.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Vertebral morphometry with DXA/MXA equipment--an equipment comparison. Dual x-ray absorptiometry/morphometric x-ray absorptiometry].

PURPOSE: The accuracy and reproducibility of morphometric measurements (Morphometric X-ray Absorptiometry = MXA) of vertebrae were determined. The significant difference of the change in height of vertebral bodies in follow-up studies was computed for MXA methods and digitised spinal radiographs as well. MATERIAL AND METHODS: The measurements were carried out on two new Dual X-ray Absorptiometry (DXA) devices (device A = Expert, Lunar Corp., device B = QDR 2000 Plus, Hologic Inc.). The data were obtained by using the European Spine Phantom (ESP) and lumbar spine specimens. RESULTS: The accuracy of vertebral morphometry performed on radiographs is 2.0%, on the device A 2.3%, and on the device B 4.9%. Measurements taken with the ESP showed a reproducibility of 1.0 to 3.0%, whereas measurements of fractured vertebrae resulted in 5.1 to 6.0%. CONCLUSION: The results of the morphometric measurements demonstrate that a reliable fracture analysis in phantoms and specimens is possible. Further in-vivo studies are necessary.

Absorptiometry, Photon↗
PubMed1997

Bone density variation and its effects on risk of vertebral deformity in men and women studied in thirteen European centers: the EVOS Study.

In Europe there is a 3-fold variation, according to geographical center, in risk of vertebral deformity in men and women over the age of 50. We investigated the relationship between bone density, as assessed by dual-energy X-ray absorptiometry (DEXA) of the spine and hip and prevalent vertebral deformities in 13 of the 36 centers participating in the European Vertebral Osteoporosis Study (EVOS). Each center recruited an age-stratified sample of men and women aged 50 years and over, and of those who agreed to densitometry, 288/2088 women and 233/1908 men were found to have one or more deformities of the vertebrae between T4 and L4 as assessed by the McCloskey algorithm. DEXA was in each case performed on L2-L4, the proximal femur, or both. Bone densitometry results were cross-calibrated between centers using the European Spine Phantom prototype and results expressed as bone mineral density (BMD, g/cm2). In both genders, subjects with deformities involving loss of anterior vertebral body height alone comprised over 20% of the total with deformities and these related poorly to BMD. Other classes of deformity were found by logistic regression to relate significantly to BMD in one or both genders, with odds ratios for the risk of any of these ranging from 1.67 to 2.11 for a 1 SD reduction in bone density at spine, femoral neck, or trochanter (p < 0.001). Adjusting for anthropometric variables and BMD did not remove the effect of age on risk which rose 1.67- to 1.78-fold per decade according to gender. The greater unadjusted rate of increase in deformity risk with age in women was attributable to their faster rate of bone loss with age; after adjusting for age, body mass index (BMI), and BMD at the trochanter in grams per square centimeter, men had a 2-fold higher risk of deformity than women. Analysis of the relationship between mean bone density and the prevalence of deformity in each center demonstrated no significant differences between centers in either gender, after adjusting for BMD, age, and BMI together with an a posteriori statistical adjustment for imperfect cross-calibration of densitometers. It is concluded that BMD is an important determinant of deformity risk in both genders. Together with age, BMD explains much of the differences in risk both between the sexes and between individual geographical centers in Europe.

Aged↗
PubMed1997

Influence of physical activity on vertebral deformity in men and women: results from the European Vertebral Osteoporosis Study.

Physical activity is associated with an increased bone mass and a reduced risk of hip fracture. There are, however, no data from population samples of men and women concerning the effect of regular levels of physical activity on the risk of vertebral deformity. The aim of this study was to determine the relationship between regular physical activity and vertebral deformity in European men and women. A population survey method was used. Thirty-six centers from 19 European countries participated. Each center recruited a population sample of men and women aged 50 years and over. Those who took part received an interviewer-administered questionnaire and lateral thoracolumbar radiographs. Subjects were asked about two dimensions of physical activity: (1) the level of physical activity undertaken either at work or at home on a daily basis at three different age periods: 15-25 years, 25-50 years, and 50+ years; and (2) the amount of time spent walking or cycling out of doors each day. Spinal radiographs were evaluated morphometrically and the presence of vertebral deformity was defined according to the McCloskey method. In total, 14,261 subjects, aged 50-79 years, from 30 centers were studied, of whom 809 (12.0%) men and 884 (11.7%) women had one or more deformities. After adjusting for age, center, smoking, and body mass index, very heavy levels of activity in all three age groups were associated with an increased risk of vertebral deformity in men (odds ratios, age adjusted [OR], 1.5-1.7; with all 95% confidence intervals [CI] excluding unity). No increased risk was observed in women. Current walking or cycling more than 1/2 h/day was associated with a reduced risk of vertebral deformity in women (OR 0.8; 95% CI 0.7-1.0). We conclude that regular walking in middle-aged and elderly women is associated with a reduced risk of vertebral deformity. By contrast, heavy levels of physical activity in early and middle adult life are associated with an increased risk in men. These differences are of relevance in understanding the epidemiology of vertebral deformity and planning programs of prevention.

Adolescent↗
PubMed1996

The prevalence of vertebral deformity in european men and women: the European Vertebral Osteoporosis Study.

Our aim was to determine the prevalence of radiographically defined vertebral deformity, as a marker of vertebral osteoporosis, in different regions and populations within Europe. We used a cross-sectional population-based survey. Population-based sampling frames were obtained from 36 centers in 19 European countries. Stratified random sampling was used to recruit 15,570 males and females aged 50-79 years. Lateral spinal radiographs were taken according to a standardized protocol, and all X-rays were evaluated centrally. Vertebral deformity was morphometrically defined according to the published methods of McCloskey and Eastell. Based on the McCloskey method, the mean center prevalence of all deformities was 12% in females (range 6-21%) and 12% in males (range 8-20%). The prevalence increased with age in both sexes though the gradient was steeper in females. There was substantial geographical variation, with the highest rates in Scandinavian countries. Radiographically defined vertebral deformity is a common disorder and equally frequent in males and females. Using standardized methodology, there is important variation in occurrence across Europe, which might suggest clues to pathogenesis.

Age Distribution↗
PubMed1996

Radial cortical and trabecular bone densities of men and women standardized with the European Forearm Phantom.

We previously showed that it is possible to cross-calibrate peripheral bone densitometers using the European Spine Phantom (ESP). We have now performed a multinational study of cross-calibrated radius bone density based on normal subjects of both sexes in eight European centers. Six centers were equipped with machines made by Scanco or Stratec for determining distal radial trabecular bone density by quantitative computed tomography (QCT) and two were equipped with Lunar SP2 single photon absorptiometry (SPA) equipment for measuring midshaft cortical bone density. Subjects recruited ranged from 20 to over 80 years of age. Over one hundred and fifteen men were studied by QCT and a different cohort of 104 men were studied with SPA; the equivalent figures for women were 235 and 123. Reference ranges were derived for bone density against age for each of the four groups, and their applicability is discussed in relation to between-center differences in the results obtained. There were insignificant differences (P > 0.05 with Bonferroni correction) between centers in the values obtained by QCT in the different populations. However, there were considerably larger and highly statistically significant differences between midshaft cortical bone density values of about 10% of overall means between subjects from eastern Finland and central Belgium (P < 0.001), with higher Finnish values. Women had considerably lower radial trabecular bone density values than men at all ages, a result that differentiates the radius from the spine. This sex difference widened after menopause. These results have important implications for understanding the contribution of bone density to the differential risk of Colles' fracture in the two sexes and suggest that further work is needed to establish young normal reference ranges for radial bone density in Europe.

Absorptiometry, Photon↗
PubMed1996

[Cost and effectiveness of different strategies in diagnosis of osteoporosis].

Osteoporosis represents one of the most common disorders in Germany. Because of the general aging of the population and due to several secular trends (less exercise, nutritional deficits, higher standard of living) the prevalence of osteoporosis will increase substantially. Therefore, it is important to develop preventive strategies and analyze them according to both medical and economical criteria. During the last couple of years substantial progress has been made both in the area of diagnostic approaches as well as treatment modalities. Thus, from a medical point of view important conditions for a positive assessment of the cost-benefit-ratio of diagnostic approaches in osteoporosis are now fulfilled. Currently, a strategy for selective screening of well-defined high risk groups appears to be most appropriate. These include 1. women with subnormal hormonal status provided that other risk factors are present, 2. patients with low-trauma fractures, 3. patients under prolonged steroid therapy, and 4. patients with secondary osteoporosis due to other causes. International studies have demonstrated that even more far-reaching preventive strategies can be conceived that could be both medically and economically effective. Currently, however, data for a detailed cost-benefit-analysis are lacking or based on outdated diagnostic equipment or treatment agents. New Studies on this topic are critically needed to evaluate preventive strategies, specifically for Germany.

Absorptiometry, Photon↗
PubMed1996

Clinical utility of bone mass measurements in adults: consensus of an international panel. The Society for Clinical Densitometry.

Low bone mass predicts future fracture risk as well as high cholesterol or high blood pressure can predict the risk of heart disease or stroke. Prevention of the first fracture should be a clinical goal. In patients without fractures, osteopenia and osteoporosis can be diagnosed based on the extent of reduction in bone mass below mean peak bone mass of young healthy individuals. As bone mass decreases, fracture risk increases exponentially. Clinical situations in which an assessment of bone mass and fracture risk affects therapeutic decisions include estrogen deficiency, vertebral abnormalities, radiographic osteopenia, asymptomatic primary hyperparathyroidism, and long-term corticosteroid therapy. Serial measurements can also be used to monitor the effects of osteoporosis treatments. The appropriate technique and skeletal site for bone mass measurements should be chosen based on the patient's circumstances and the precision of measurement. A clinical interpretation can enhance the value of computer-generated bone mass measurement reports and improve decision making.

Absorptiometry, Photon↗
PubMed1996

[Systematics of osteodensitometric methods and acronyms].

The radiological diagnosis of osteoporosis is primarily based on osteodensitometry. The continuous development of new methods requires persistent analysis of its potential and limits. The knowledge of the differences of osteodensitometric methods is essential for understanding patient reports. The acronyms are internationally established, their correct usage is advocated.

Abbreviations as Topic↗
PubMed1996

[CT osteodensitometry in the area immediate to hip endoprostheses].

UNLABELLED: The value of metal artifact reduction in quantitative bone density determination in the vicinity of metallic implants was studied. METHOD: Ten cadaver femora with hip endoprostheses implanted intra vitam were examined in CT with varying slice thicknesses, tube voltage, scan time and magnification factor. The artifact-laden images were then processed using a metal artifact reduction programme (MAR). The metallic implant was removed, allowing the bone slices to be examined again with the same imaging parameters, but without the bothersome metal artifacts. This allowed comparison of bone density values obtained before and after application of MAR with data obtained after implant removal. RESULTS: A comparison of the bone density measurements between the sample group without implants and the group with indwelling implants prior to MAR showed an unexpected correlation coefficient r = 0.975-0.977. The correlation coefficients after MAR rose to r = 0.987-0.992 in 125 kV and r = 0.989-0.991 in 85 kV modes. The reproducibility of the density measurements for the groups without implants and with implants following MAR showed variation coefficients (VC) of 1.16% and 0.75% respectively. The reproducibility of the manual definition of the region of interest (ROI) in bone showed a VC = 2.19%. CONCLUSIONS: Bone density in the vicinity of metallic implants can be reliably and reproducibly determined using MAR.

Artifacts↗
PubMed1995

Dual X-ray absorptiometry of the proximal femur: normal European values standardized with the European Spine Phantom.

Measurements of the proximal femur by dual X-ray absorptiometry (DXA) are assuming increasing importance in clinical and epidemiological studies. However, different DXA manufacturers have adopted varying approaches to measuring the femoral neck and trochanter regions with the result that there is as yet no agreement on normal ranges and how to cross-calibrate between different machines. In this Concerted Action (of the EU's 2nd Framework Programme), 12 clinical centers in eight countries recruited a total of 855 female and 517 male Caucasian subjects who were judged to be free of conditions known to cause secondary osteoporosis and who had not been treated with drugs known to affect bone mass. The DXA machines used were made by Hologic, Lunar, and Norland. Each machine was cross-calibrated with the European Spine Phantom prototype designed by Kalender. All femoral neck and trochanter results were expressed as standardized values and were first examined for possible bias due to between-brand differences in choice of areas for measurement. On average, trochanter areas were similar between brands but Norland chose a narrower neck region for analysis. Bone mineral density (BMA or BMD g/cm2) was log-normally distributed for all groups at the femoral neck but normally distributed at the trochanter in men and postmenopausal women. There were substantial between-center differences after cross-calibration in age-adjusted mean values at both sites and also in the rates of apparent bone loss with age and the amounts of scatter within populations about mean age-adjusted values. With the proviso that locally derived normal ranges would allow more accurate comparisons for clinical purposes, European normal ranges were derived for both neck and trochanter. Data obtained with the three individual brands of machine fitted these overall ranges well. Bone loss was apparent in premenopausal women at the femoral neck but not the trochanter. Postmenopausal women's data was somewhat better fitted by reference to years since menopause than to chronological age. This work provides a basis for conducting future epidemiological and clinical studies with more than one brand of machine as long as each individual subject, if measured consecutively, is measured on the same machine throughout.

Absorptiometry, Photon↗
PubMed1995

European semi-anthropomorphic spine phantom for the calibration of bone densitometers: assessment of precision, stability and accuracy. The European Quantitation of Osteoporosis Study Group.

Up to now it has not been possible to reliably cross-calibrate dual-energy X-ray absorptiometry (DXA) densitometry equipment made by different manufacturers so that a measurement made on an individual subject can be expressed in the units used with a different type of machine. Manufacturers have adopted various procedures for edge detection and calibration, producing various normal ranges which are specific to each individual manufacturer's brand of machine. In this study we have used the recently described European Spine Phantom (ESP, prototype version), which contains three semi-anthropomorphic "vertebrae" of different densities made of stimulated cortical and trabecular bone, to calibrate a range of DXA densitometers and quantitative computed tomography (QCT) equipment used in the measurement of trabecular bone density of the lumbar vertebrae. Three brands of QCT equipment and three brands of DXA equipment were assessed. Repeat measurements were made to assess machine stability. With the large majority of machines which proved stable, mean values were obtained for the measured low, medium and high density vertebrae respectively. In the case of the QCT equipment these means were for the trabecular bone density, and in the case of the DXA equipment for vertebral body bone density in the posteroanterior projection. All DXA machines overestimated the projected area of the vertebral bodies by incorporating variable amounts of transverse process. In general, the QCT equipment gave measured values which were close to the specified values for trabecular density, but there were substantial differences from the specified values in the results provided by the three DXA brands. For the QCT and Norland DXA machines (posteroanterior view), the relationships between specified densities and observed densities were found to be linear, whereas for the other DXA equipment (posteroanterior view), slightly curvilinear, exponential fits were found to be necessary to fit the plots of observed versus specified densities. From these plots, individual calibration equations were derived for each machine studied. For optimal cross-calibration, it was found to be necessary to use an individual calibration equation for each machine. This study has shown that it is possible to cross-calibrate DXA as well as QCT equipment for the measurement of axial bone density. This will be of considerable benefit for large-scale epidemiological studies as well as for multi-site clinical studies depending on bone densitometry.

Absorptiometry, Photon↗
PubMed1995

The European Spine Phantom--a tool for standardization and quality control in spinal bone mineral measurements by DXA and QCT.

The lack of standardization in bone mineral measurements of the lumbar spine and other skeletal sites is generally recognized as an important and unresolved issue. We report and discuss efforts at standardization and cross-calibration of DXA and QCT equipment. We have designed and tested a geometrically defined, semi-anthropomorphic phantom, the European Spine Phantom (ESP). It contains a spine insert consisting of three vertebrae of increasing bone mineral densities and thicknesses of cortical structures; the respective parameters are given in tabular form for the final phantom design. Results for cross-calibration with the ESP compare well with patient results. Measurements on the first 30 phantoms confirmed that the ESP can be manufactured with a variation of about 1%. We conclude that the ESP is suitable for daily quality assurance, cross-calibration of instruments and universal standardization. The ESP was used to establish standardized BMD (sBMD) units for DXA equipment going into effect in late 1995. Its acceptance by manufacturers as a calibration standard for DXA and QCT measurements appears imminent.

Absorptiometry, Photon↗
PubMed1995

Recent developments in DXA. Quality of new DXA/MXA-devices for densitometry and morphometry.

The introduction of new devices demands the assessment of their capabilities in established terms. The accuracy, reproducibility and spatial resolution of in vitro (phantom) osteodensitometric and morphometric measurements of QDR 2000 Plus and EXPERT are presented. Design details of these DXA/MXA-devices are listed and discussed in combination with the data acquired in the test measurements and calculations. The image quality will improve with further software developments. The long-term reproducibility and in vivo reliability remains to be evaluated.

Absorptiometry, Photon↗
PubMed1995

Dual X-ray absorptiometry--cross-calibration and normative reference ranges for the spine: results of a European Community Concerted Action.

Bone density measurements by dual X-ray absorptiometry (DXA) of the spine can now be made precisely, but there is no uniformity in reporting results and in presenting reference data. A European Union Concerted Action therefore devised a uniform procedure for cross-calibrating and standardizing instruments, using the European spine phantom (ESP) prototype. This phantom differs in a number of respects from the final version of the ESP. Eighteen centers in nine countries obtained 1619 records (1035 women) from Caucasian subjects, aged 20-80 years, drawn from normal populations. The DXA machines used were made by the Hologic, Lunar, and Norland companies. Highly statistically significant differences were evident between populations, both in apparent rates of bone loss with age and in the spread of values about the age-adjusted means. There were small residual differences in the results obtained with the three machine brands which could have been due to the relatively large between-center population differences we observed. The alternative or additional explanation that they were attributable, in part, to the design differences between the ESP prototype and the definitive ESP, which became available after this study was completed, was shown to be a valid possibility. Results from postmenopausal women reported in relation to the years that have elapsed since menopause showed reduced population variance when compared with conventional reporting in relation to age. After cross-calibration, the center with the highest age-adjusted normal density value averaged 23% more than the center with the lowest. It is therefore crucially important to select appropriate reference data in clinical and epidemiological studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1995

Vertebral fractures in men and women: how discriminative are bone mass measurements?

Vertebral fractures are associated with osteoporosis. This study examined men and women with vertebral deformation/fractures, as defined by vertebral morphometry. These were compared with a population derived group measured contemporaneously who were defined as having no vertebral deformation/fracture by the radiographs. All patients underwent a dual energy X-ray absorptiometry (DXA) scan of the spine and hip, and a broadband ultrasound attenuation (BUA) scan of their os calcis. The abilities of these two techniques were compared for their discriminatory powers in this type of fracture. The results showed that DXA hip and spine had a better discriminatory power in the female vertebral group compared with BUA. In males none of the bone measurements could discriminate between the fracture and non-fracture groups.

Absorptiometry, Photon↗
PubMed1995

[Value of transdermal hormone substitution for postmenopausal osteoporosis].

The osteoporosis is a major public health problem occurring primarily among the postmenopausal women. The relationship to the loss of ovarian function is undoubtful. The consequence of this knowledge is to substitute the hormone deficiency. Hormone replacement therapy (HRT) is effective with oral, subcutaneous, parenteral, and transdermal application. The transdermal hormone replacement therapy for prevention and therapy (early phase) of postmenopausal osteoporosis is effective and sure. The osteoprotective effect was demonstrated in multiple studies. The effectiveness of the HRT can be demonstrated by osteodensitometry and measuring markers of bone resorption.

Administration, Cutaneous↗
PubMed1994

Variation in vertebral height ratios in population studies. European Vertebral Osteoporosis Study Group.

Vertebral height ratios are used to define vertebral deformity in clinical and epidemiologic studies of vertebral osteoporosis. However, few data have been obtained on the variation in these ratios in different populations using standard methods. We examined vertebral morphometric measurements obtained in a population survey from three centers: Malmö (Sweden), Montceau-les-Mines (France), and Graz (Austria), to study the influence of sex and the population center on vertebral height ratios. Radiographs were obtained according to a standardized protocol, and morphometric measurements, anterior height Ha, central height Hc, and posterior height Hp, made in Berlin. The height ratios anterior, Ha/Hp, central, Hc/Hp, posterior I, Hp/Hp', and posterior II, Hp/Hp" (Hp' = posterior height of vertebrae above, Hp" = posterior height of vertebrae below) were calculated for each vertebra from T4 to L4. The mean and standard deviation of these ratios for each sex and each center were derived using a statistical trimming procedure to normalize the distribution. Threshold values for defining grade 1 and grade 2 deformities, wedge, biconcavity, and compression, were calculated using these parameters. Anterior and central vertebral height ratios were smaller in males than females (p < 0.01). There were significant differences between the three centers (p < 0.01) both in the trimmed mean values for anterior and central vertebral height ratios and in the thresholds derived using standard criteria for defining wedge and biconcavity deformity. The data confirm the impression from single-center studies that vertebral height ratios vary between populations and suggest that reference values for vertebral height ratios should be derived separately for males and females within individual populations whenever possible.

Aged↗