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  • 1
    Electronic Resource
    Electronic Resource
    Automatic quantification of vertebral cancellous bone remodeling during aging (1985)
    Springer
    Surgical and radiologic anatomy 7 (1985), S. 203-208 
    Details
    ISSN: 1279-8517
    Keywords: Vertebra ; Image analysis ; Trabecular bone ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les modifications anatomiques de l'os spongieux vertébral au cours du vieillissement ont été quantifiées par analyse automatique d'image, à partir de microradiographies de coupes sagittales de 1 mm d'épaisseur, effectuées sur des vertèbres lombaires autopsiques normales (24 hommes et 28 femmes de 35 à 96 ans). En quatre décennies, la perte osseuse due à l'âge est, au centre de la vertèbre, de 60% chez les femmes et 45% chez les hommes. Il y a une nouvelle répartition des travées: mesurées sur une coupe sagittale, les travées porteuses sont deux fois (sujets jeunes) à six fois (sujets âgés) plus nombreuses que les travées transverses. Avec l'âge, les espaces intertrabéculaires s'agrandissent, tandis que les travées s'amincissent et disparaissent.
    Notes: Summary Anatomical transformation changes in vertébral spongy bone were quantified by automatic image analysis of microradiographs of 1 mm-thick sagittal slices from autopsied normal lumbar vertebrae (24 men and 28 women, age 35 to 96). Over a period of four decades, aging bone loss is 60% in women and 45% in men in the center of the vertebral body. With age, there is a new distribution of trabeculae: weight-bearing ones are twice (in young people) to six times (in old people) more numerous than transverse ones (measured on a sagittal slice). In the elderly, intertrabecular spaces enlarge while the proportion of the thinnest trabeculae increases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01654642
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  • 2
    Electronic Resource
    Electronic Resource
    CT image analysis of the vertebral trabecular network in vivo (1992)
    Springer
    Calcified tissue international 51 (1992), S. 8-13 
    Details
    ISSN: 1432-0827
    Keywords: CT analysis ; Vertebral trabecular network ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A method of computed tomography (CT) image analysis of lumbar vertebrae has been developed, providing a visualization of the trabecular network as it is represented in a 1.5 mm-thick CT image. We measured the length of the network and the number of discontinuities found in the image. The ratio of these measurements was called the “trabecular fragmentation index” (TFI). CT images from 71 women between the ages of 50 and 59, and 94 women between the ages of 60 and 69 were divided into three groups according to quantitative computed tomography (QCT) vertebral density and to the presence or absence of crushing and fractures. The measure of the network length versus the vertebral area was significantly higher in normal subjects than in osteoporotics. A TFI threshold at 0.195 could separate the normal subjects, regardless of the decade, from osteoporotic ones. In females between 50 and 69 years of age, TFI was 0.166 (SD=0.031) for the normal group and 0.248 (SD=0.082) for osteoporotics. The osteopenic group without fractures but low bone mineral density (BMD) showed an intermediate TFI of 0.195 (SD=0.05), placing this population on both sides of the threshold. Correlation between TFI and BMD was only-0.60. TFI could provide new information in vivo about the state of trabecular structure, particularly in the osteopenic group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296208
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  • 3
    Electronic Resource
    Electronic Resource
    European semi-anthropomorphic spine phantom for the calibration of bone densitometers: Assessment of precision, stability and accuracy the European quantitation of osteoporosis study group (1995)
    Springer
    Osteoporosis international 5 (1995), S. 174-184 
    Details
    ISSN: 1433-2965
    Keywords: Cross-calibration ; Dual X-ray absorptiometry (DXA) ; European Spine Phantom (ESP) ; Osteoporosis ; Quantitative computed tomography (QCT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 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 simulated 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02106097
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Dual-energy X-ray absorptiometry of the calcaneus: Comparison with vertebral dual-energy X-ray absorptiometry and quantitative computed tomography (1995)
    Springer
    Calcified tissue international 56 (1995), S. 14-18 
    Details
    ISSN: 1432-0827
    Keywords: Calcaneus ; Bone mineral content ; DXA ; QCT ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The purpose of this study was to determine the efficacy of using bone mineral measurements of the calcaneus to evaluate osteoporosis. Dual energy X-ray absorptiometry (DXA) of the calcaneus was compared with posteroanterior lumbar absorptiometry (DXA) and vertebral quantitative computed tomography (QCT) measurements in 171 white women (78 normal and 93 osteoporotic). DXA measurement of os calcis mineralization decreased significantly in osteoporosis, but to a lesser extent than in vertebral sites. In normal subjects, good correlations were observed between calcaneal and lumbar DXA (0.69) and QCT (0.56). In subjects with vertebral fractures, there was also good correlation between calcaneal DXA and QCT (0.59–0.69). This suggests that trabecular bone in calcaneus and vertebrae have related involution in cases of vertebral osteoporosis. However, the extent of bone loss is less marked in the calcaneus than in the vertebrae and is not sufficient to be accurately measured over time. We conclude, therefore, that although the global densitometric measurement at this site is not sufficiently sensitive for general use, it can be useful as a epidemiological research tool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298738
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  • 5
    Electronic Resource
    Electronic Resource
    Bone Density Reduction in Various Measurement Sites in Men and Women with Osteoporotic Fractures of Spine and Hip: The European Quantitation of Osteoporosis Study (1999)
    Springer
    Calcified tissue international 64 (1999), S. 191-199 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Dual X-ray absorptiometry — Quantitative computed tomography — Hip fracture — Spine fracture — Osteoporosis—Normal ranges.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. We have measured bone mineral density (BMD) using dual X-ray absorptiometry (DXA) of the spine and hip, spinal quantitative computed tomography (QCTspi), and peripheral radial quantitative computed tomography (pQCTrad) in 334 spine and 51 hip fracture patients. The standardized hip and spine BMD for each patient was calculated and compared with the combined reference ranges published previously, each densitometer having been cross-calibrated with the prototype European Spine Phantom (ESPp) or the European Forearm Phantom (EFP). Male and female fracture cases had similar BMD values after adjusting for body size, where appropriate. This suggests that the relationship between bone density (mass per unit volume) and fracture risk is similar between men and women. However, compared with age-matched controls, mean decreases in BMD ranged from 0.78 SD units (women with hip fracture, DXAspi) to 2.57 SD units (men with spine fractures, QCTspi). The proportion of spine and hip fracture patients falling below the cutoff for osteoporosis (T-score 〈−2.5 SD) proposed by the World Health Organization (WHO) study group varied according to different BMD measurement procedures (range 18–94%). This finding suggests that the WHO definition requires different thresholds when used with non-DXA BMD measurement techniques. Receiver operator characteristic (ROC) analysis was used to compare measurement techniques for their ability to discriminate between cases and controls. Among DXA sites, the proximal femur was preferred when evaluating generalized bone loss, particularly in elderly people. An additional spinal BMD measurement may add clinical value if spine fracture risk assessment has a high priority. Both axial and peripheral QCT techniques performed comparably to DXA in spinal osteoporosis, so investigators and clinicians may use any of the three technologies with similar degrees of confidence for the diagnosis of generalized or site-specific bone loss providing straightforward clinical guidelines are followed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900601
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    Paper (German National Licenses)
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