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The reduction in the trabecular parameters at the radius was worse in women than in men [ 9 ]. Thus, although invasive bone biopsy remains the gold standard for determination of bone mineralization and turnover, it is probably not the best measure of bone volume.
Clearly the cortex is an important contributor of bone strength. The use of micro-CT in dialysis patients is novel and this allows more precise definition of the bone structure than the 2-dimensional histology. However, both techniques are limited by the small size of the bone sample and the location of the biopsy. Although not as precise, dual energy radiographic densitometry measurements of the radius provide a measure of cortical bone loss that is practical and widely available, but we lack prospective studies in dialysis patients that have adequate power to determine relationship to skeletal fractures.
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Product | Noninvasive Assessment of Trabecular Bone Architecture and the Competence of Bone
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Institutional Login Shibboleth or OpenAthens For the academic login, please select your organization on the next page. Forgot Password? Sign up for MyKarger Institutional Login. Download Fulltext PDF. Free Access. Susan M. Related Articles for " ". Am J Nephrol ;— Go to Top Abstract. FullText PDF. Related Articles:. Parfitt AM: Misconceptions 2 : turnover is always higher in cancellous than in cortical bone.
Bone ; — References Parfitt AM: Misconceptions 2 : turnover is always higher in cancellous than in cortical bone. Library Recommendation.
In this context, the study of trabecular microarchitecture has much to contribute. The emerging field of trabecular microarchitecture, however, is diverse, inter-disciplinary and encompasses many different imaging modalities. This volume represents a compilation of papers from world-renowned researchers, reflecting the most current research in the area of noninvasive assessment of trabecular microcarchitecture. This varied research applies sophisticated imaging tools to questions of bone biomechanics at both the basic science and clinical levels.
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The invention is applicable in vivo, particularly on human subjects, or ex vivo. Provisional Application No. The government may have certain rights in this invention. This invention relates generally to the field of digital topological analysis DTA to derive structural parameters from trabecular bone images obtained by magnetic resonance imaging MRI , computed tomography CT , or other imaging technologies, and the use of these parameters to assess trabecular bone structure in patients at risk of developing fractures from osteoporosis or those suffering from metabolic bone disorders. Trabecular bone TB also known as cancellous bone , which occurs in most of the axial skeleton and at locations toward the ends of the long bones, consists of a lattice of interconnected plates and rods that confer mechanical strength to the skeleton at minimum weight.
In addition to the volume fraction of the trabecular bone often quantified in terms of bone density , the three-dimensional 3D arrangement of the trabecular network is a major determinant of elastic modulus Odgaard et al. In general, characterization of the strength of trabecular lattices from three-dimensional 3D images can be divided into three major categories: material, scale and topology DeHoff et al.
Microscopy These parameters change characteristically with subject age. It is also widely accepted that the mechanical competence of trabecular bone i. This method, however, does not distinguish between trabecular and cortical bone and ignores the role of structure as a contributor to mechanical competence. It has been shown that the 3D arrangement Mosekilde, Bone and the nature of the trabeculae e. Orthopaedic Res.
Biomechanics In models of trabecular bone, Jensen et al.
Bone demonstrated that the apparent stiffness can vary by a factor of when the arrangement of the network goes from a perfect cubic lattice to maximum irregularity, even though trabecular bone volume remains almost constant. The independent role of architecture in conferring strength to the trabecular network is supported by a large number of experimental studies Gordon et al. Tissue Int. The clinical evidence for an independent contribution from trabecular architecture is equally compelling.
In the past, studies concerned with the quantitative description of trabecular bone have used histomorphometry from sections in conjunction with stereology to reconstruct the third dimension Parfitt, In Bone Histomorphometry: Techniques and Interpretation , Boca Raton, Fla. Several studies involving histomorphometry in patients with and without vertebral fractures, matched for gender and BMD, found the two groups of subjects to differ in histomorphometric indices.
Kleerekoper et al.
toiuatexam.thinkexam.com/tracking-device-for-motorola-moto-z3.php Similarly, Recker Calcif. Legrand et al. Bone Miner.
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However, trabecular number was lower and trabecular separation greater in the fracture group. Other distinguishing histomorphometric parameters were found to relate to network connectivity. As pointed out, most measurements of trabecular architecture are based on two-dimensional 2D images Gordon et al. Yet, it is well known that connectivity analysis of 2D sections does not accurately define the 3D structures found in trabecular bone networks Odgaard et al. For example, what appears to be a rod in a 2D section, may actually be a cross-section of a plate-like structure in the 3D network, or even a junction between two plates.
A 3D analysis is thus essential to unambiguously establish the topology of the trabecular architecture Wessels et al. In vivo assessment of trabecular bone architecture can be achieved by computed tomography Gordon et al. Bone Mineral Res.
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Health Care 6 , and magnetic resonance MR micro-imaging Link et al. Health Care A. Studies performed in patients are usually conducted at peripheral skeletal locations, such as the wrist Majumdar et al. Recent advances have permitted analysis of the resulting images by probability-based image processing techniques Hwang et al. Imaging Systems and Technol.
One potentially powerful approach toward characterizing and quantifying trabecular network architecture is based on topological evaluation of the structure. Topology is the branch of mathematics concerned with the geometric properties of deformable objects that are invariant in scale, rotation and translation Maunder, Algebraic Topology , Cambridge, UK: Cambridge Univ.
Press, For example, topological criteria allow a determination as to whether a particular point in the network is part of a surface, curve, or junction. To illustrate the difference between topology and scale, one can consider a trabecular bone network that undergoes slight uniform thickening. Topologically, the network remains unaltered, but the scale properties have changed, which will result in changes to the mechanical properties.
Here, the two networks differ in topology. Feldkamp et al. The investigators reasoned that connectivity is impossible to derive from images of two-dimensional sections, hence they expressed connectivity in terms of a global network, referred to as the Euler characteristic or number. The Euler characteristic, derived from the Euler-Poincare formula, assumes the number of bone objects to be one, and that marrow cavities do not exist in the network.
These assumptions make the Euler characteristics equivalent to the first Betti number Feldkamp et al.