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Paolo Russo - One of the best experts on this subject based on the ideXlab platform.
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dataset of patient derived digital breast phantoms for in silico studies in breast computed tomography digital breast tomosynthesis and digital mammography
Medical Physics, 2021Co-Authors: Antonio Sarno, G Mettivier, Francesca Di Franco, Antonio Varallo, Kristina Bliznakova, Andrew M Hernandez, John M Boone, Paolo RussoAbstract:PURPOSE To present a dataset of computational digital breast phantoms derived from high-resolution three-dimensional (3D) clinical breast images for the use in virtual clinical trials in two-dimensional (2D) and 3D x-ray breast imaging. ACQUISITION AND VALIDATION METHODS Uncompressed computational breast phantoms for investigations in dedicated breast CT (BCT) were derived from 150 clinical 3D breast images acquired via a BCT scanner at UC Davis (California, USA). Each image voxel was classified in one out of the four main materials presented in the field of view: fibroglandular tissue, adipose tissue, skin tissue, and air. For the image classification, a semi-automatic software was developed. The semi-automatic classification was compared via manual glandular classification performed by two researchers. A total of 60 compressed computational phantoms for virtual clinical trials in digital mammography (DM) and digital breast tomosynthesis (DBT) were obtained from the corresponding uncompressed phantoms via a software algorithm simulating the compression and the Elastic deformation of the breast, using the tissue's Elastic Coefficient. This process was evaluated in terms of glandular fraction modification introduced by the compression procedure. The generated cohort of 150 uncompressed computational breast phantoms presented a mean value of the glandular fraction by mass of 12.3%; the average diameter of the breast evaluated at the center of mass was 105 mm. Despite the slight differences between the two manual segmentations, the resulting glandular tissue segmentation did not consistently differ from that obtained via the semi-automatic classification. The difference between the glandular fraction by mass before and after the compression was 2.1% on average. The 60 compressed phantoms presented an average glandular fraction by mass of 12.1% and an average compressed thickness of 61 mm. DATA FORMAT AND ACCESS The generated digital breast phantoms are stored in DICOM files. Image voxels can present one out of four values representing the different classified materials: 0 for the air, 1 for the adipose tissue, 2 for the glandular tissue, and 3 for the skin tissue. The generated computational phantoms datasets were stored in the Zenodo public repository for research purposes (http://doi.org/10.5281/zenodo.4529852, http://doi.org/10.5281/zenodo.4515360). POTENTIAL APPLICATIONS The dataset developed within the INFN AGATA project will be used for developing a platform for virtual clinical trials in x-ray breast imaging and dosimetry. In addition, they will represent a valid support for introducing new breast models for dose estimates in 2D and 3D x-ray breast imaging and as models for manufacturing anthropomorphic physical phantoms.
Kay Raum - One of the best experts on this subject based on the ideXlab platform.
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longitudinal Elastic properties and porosity of cortical bone tissue vary with age in human proximal femur
Bone, 2013Co-Authors: Markus K H Malo, Jukka S Jurvelin, Juha Toyras, Daniel Rohrbach, Hanna Isaksson, Inari S Tamminen, Heikki Kroger, Kay RaumAbstract:Abstract Tissue level structural and mechanical properties are important determinants of bone strength. As an individual ages, microstructural changes occur in bone, e.g., trabeculae and cortex become thinner and porosity increases. However, it is not known how the Elastic properties of bone change during aging. Bone tissue may lose its Elasticity and become more brittle and prone to fractures as it ages. In the present study the age-dependent variation in the spatial distributions of microstructural and microElastic properties of the human femoral neck and shaft were evaluated by using acoustic microscopy. Although these properties may not be directly measured in vivo, there is a major interest to investigate their relationships with the linear Elastic measurements obtained by diagnostic ultrasound at the most severe fracture sites, e.g., the femoral neck. However, before the validity of novel in vivo techniques can be established, it is essential to understand the age-dependent variation in tissue Elastic properties and porosity at different skeletal sites. A total of 42 transverse cross-sectional bone samples were obtained from the femoral neck (Fn) and proximal femoral shaft (Ps) of 21 men (mean ± SD age 47.1 ± 17.8, range 17–82 years). Samples were quantitatively imaged using a scanning acoustic microscope (SAM) equipped with a 50 MHz ultrasound transducer. Distributions of the Elastic Coefficient (c33) of cortical (Ct) and trabecular (Tr) tissues and microstructure of cortex (cortical thickness Ct.Th and porosity Ct.Po) were determined. Variations in c33 were observed with respect to tissue type (c33Tr c33(Ct.Fn) = 35.3 GPa > c33(Tr.Ps) = 33.8 GPa > c33(Tr.Fn) = 31.9 GPa), and cadaver age (R2 = 0.28–0.46, p
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longitudinal Elastic properties and porosity of cortical bone tissue vary with age in human proximal femur
Bone, 2013Co-Authors: Markus K H Malo, Jukka S Jurvelin, Juha Toyras, Daniel Rohrbach, Hanna Isaksson, Inari S Tamminen, Heikki Kroger, Kay RaumAbstract:Tissue level structural and mechanical properties are important determinants of bone strength. As an individual ages, microstructural changes occur in bone, e.g., trabeculae and cortex become thinner and porosity increases. However, it is not known how the Elastic properties of bone change during aging. Bone tissue may lose its Elasticity and become more brittle and prone to fractures as it ages. In the present study the age-dependent variation in the spatial distributions of microstructural and microElastic properties of the human femoral neck and shaft were evaluated by using acoustic microscopy. Although these properties may not be directly measured in vivo, there is a major interest to investigate their relationships with the linear Elastic measurements obtained by diagnostic ultrasound at the most severe fracture sites, e.g., the femoral neck. However, before the validity of novel in vivo techniques can be established, it is essential to understand the age-dependent variation in tissue Elastic properties and porosity at different skeletal sites. A total of 42 transverse cross-sectional bone samples were obtained from the femoral neck (Fn) and proximal femoral shaft (Ps) of 21 men (mean±SD age 47.1±17.8, range 17-82years). Samples were quantitatively imaged using a scanning acoustic microscope (SAM) equipped with a 50MHz ultrasound transducer. Distributions of the Elastic Coefficient (c33) of cortical (Ct) and trabecular (Tr) tissues and microstructure of cortex (cortical thickness Ct.Th and porosity Ct.Po) were determined. Variations in c33 were observed with respect to tissue type (c33Tr c33(Ct.Fn)=35.3GPa>c33(Tr.Ps)=33.8GPa>c33(Tr.Fn)=31.9GPa), and cadaver age (R(2)=0.28-0.46, p<0.05). Regional variations in porosity were found in the neck (superior 13.1%; inferior 6.1%; anterior 10.1%; posterior 8.6%) and in the shaft (medial 9.5%; lateral 7.7%; anterior 8.6%; posterior 12.0%). In conclusion, significant variations in Elastic Coefficients were detected between femoral neck and shaft as well as between the quadrants of the cross-sections of neck and shaft. Moreover, an age-related increase in cortical porosity and a stiffening of the bone tissue were observed. These findings may explain in part the increase in susceptibility to suffer low energy fractures during aging and highlight the potential of ultrasound in clinical osteoporosis diagnostics.
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variations of microstructure mineral density and tissue Elasticity in b6 c3h mice
Bone, 2007Co-Authors: Kay Raum, Tobias Hofmann, Ingrid Leguerney, Amena Saied, Francoise Peyrin, Laurence Vico, Pascal LaugierAbstract:200-MHz scanning acoustic microscopy (SAM) and synchrotron radiation μCT (SR-μCT) were used to assess microstructural parameters, acoustic impedance Z and tissue degree of mineralization of bone (DMB) in site-matched regions of interest in femoral bone of two inbred strains. Transverse femoral sections taken from 5 C57BL/6J@Ico (B6) and 5 C3H/HeJ@Ico (C3H) mice (5.5 months old) were explored. Mass density ρ, Elastic Coefficient c11 and Young's modulus E1 were locally derived in the distal epiphysis, distal metaphysis for trabecular bone and mid-diaphysis for cortical bone using a rule-of-mixture model. Structural parameter estimations obtained from X-ray tomographic and acoustic images were almost identical. Both strains had the same bone diameter, but the C3H mice had greater cortical thickness and smaller cancellous diameter than did B6 mice. The average DMB and impedance values were in the range between 1.13 and 1.33 g cm− 3 and 5.8 and 7.8 Mrayl, respectively. All tissue parameters were lower in B6 mice than in C3H mice. However, interstrain differences of DMB were much less (up to 3.8%) than differences of Z (up to 13.2%). SAM and SR-μCT fulfill the requirement for a simultaneous evaluation of cortical bone microstructure and material properties at the tissue level. However, SAM provides a quantitative estimate of Elastic properties at the tissue level that cannot be captured by SR-μCT. The strong differences in the measured acoustic impedances among the two inbred strains indicate that the impedance is a good parameter to detect genetic variations of the skeletal phenotype in small animal models.
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Assessment of Anisotropic Tissue Elasticity of Cortical Bone from High-Resolution, Angular Acoustic Measurements
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2007Co-Authors: Sannachi Lakshmanan, Andreas Bodi, Kay RaumAbstract:Assessment of anisotropic Elastic properties at the tissue level is still one of the major challenges in bone research. In previous studies, bone sections were cut in different directions relative to a principle axis of symmetry. This causes a high preparation and measurement effort. We have developed a new acoustic scanning procedure that allows one to measure the angular dependence of the acoustic impedance of cylindrically shaped samples (diameter: 4.4 mm) with a single measurement. Our scanning acoustic microscope was equipped with a rotational stage, and a scanning procedure was developed that measures the surface reflection of the rotating cylinder. It was shown in a previous study that the acoustic impedance derived from the reflection Coefficient is highly correlated with the Elastic Coefficient in the probing direction. From the angular reflection, the independent Elastic Coefficients were derived using assumptions of transverse isotropy and continuum micromechanical model constraints. This method was applied to the inspection of human femoral bone samples. Four cylinders were prepared from the anterior, posterior, medial, and lateral regions. The measurements were performed with a 50 MHz transducer, providing a lateral resolution of 23 mum. Remarkable structural and Elastic variations were observed between the four samples. The means and standard deviations of the derived Elastic Coefficients were: c33 = 29.9 plusmn 5.0 GPa, c11 - 21.9 plusmn 2.1 GPa, C12 = 9.2 plusmn 1.5 GPa, c13 = 9.7 plusmn 1.6 GPa, and c44 = 6.7 plusmn 1.2 GPa. The results demonstrate that microstructural and anisotropic Elastic tissue parameters can be assessed by ultrasound in very small bone samples.
Pascal Laugier - One of the best experts on this subject based on the ideXlab platform.
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quantification of nonlinear Elasticity for the evaluation of submillimeter crack length in cortical bone
Journal of The Mechanical Behavior of Biomedical Materials, 2015Co-Authors: Sylvain Haupert, Francoise Peyrin, Sandra Guerard, David Mitton, Pascal LaugierAbstract:The objective of this study was to investigate the sensitivity of the nonlinear Elastic properties of cortical bone to the presence of a single submillimetric crack. Nonlinear Elasticity was measured by nonlinear resonant ultrasound spectroscopy (NRUS) in 14 human cortical bone specimens. The specimens were parallelepiped beams (50×2×2 mm3). A central notch of 500 µm was made to control crack initiation and propagation during four-point bending. The nonlinear hysteretic Elastic and dissipative parameters αf and αQ, and Young׳s modulus Eus were measured in dry condition for undamaged (control) specimens and in dry and wet conditions for damaged specimens. The length of the crack was assessed using synchrotron radiation micro-computed tomography (SR-μCT) with a voxel size of 1.4 μm. The initial values of αf, measured on the intact specimens, were remarkably similar for all the specimens (αf =−5.5±1.5). After crack propagation, the nonlinear Elastic Coefficient αf increased significantly (p<0.006), with values ranging from −4.0 to –296.7. Conversely, no significant variation was observed for αQ and Eus. A more pronounced nonlinear Elastic behavior was observed in hydrated specimens compared to dry specimens (p<0.001) after propagation of a single submillimetric crack. The nonlinear Elastic parameter αf was found to be significantly correlated to the crack length both in dry (R=0.79, p<0.01) and wet (R=0.84, p<0.005) conditions. Altogether these results show that nonlinear Elasticity assessed by NRUS is sensitive to a single submillimetric crack induced mechanically and suggest that the humidity must be strictly controlled during measurements.
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variations of microstructure mineral density and tissue Elasticity in b6 c3h mice
Bone, 2007Co-Authors: Kay Raum, Tobias Hofmann, Ingrid Leguerney, Amena Saied, Francoise Peyrin, Laurence Vico, Pascal LaugierAbstract:200-MHz scanning acoustic microscopy (SAM) and synchrotron radiation μCT (SR-μCT) were used to assess microstructural parameters, acoustic impedance Z and tissue degree of mineralization of bone (DMB) in site-matched regions of interest in femoral bone of two inbred strains. Transverse femoral sections taken from 5 C57BL/6J@Ico (B6) and 5 C3H/HeJ@Ico (C3H) mice (5.5 months old) were explored. Mass density ρ, Elastic Coefficient c11 and Young's modulus E1 were locally derived in the distal epiphysis, distal metaphysis for trabecular bone and mid-diaphysis for cortical bone using a rule-of-mixture model. Structural parameter estimations obtained from X-ray tomographic and acoustic images were almost identical. Both strains had the same bone diameter, but the C3H mice had greater cortical thickness and smaller cancellous diameter than did B6 mice. The average DMB and impedance values were in the range between 1.13 and 1.33 g cm− 3 and 5.8 and 7.8 Mrayl, respectively. All tissue parameters were lower in B6 mice than in C3H mice. However, interstrain differences of DMB were much less (up to 3.8%) than differences of Z (up to 13.2%). SAM and SR-μCT fulfill the requirement for a simultaneous evaluation of cortical bone microstructure and material properties at the tissue level. However, SAM provides a quantitative estimate of Elastic properties at the tissue level that cannot be captured by SR-μCT. The strong differences in the measured acoustic impedances among the two inbred strains indicate that the impedance is a good parameter to detect genetic variations of the skeletal phenotype in small animal models.
Xingbin Pan - One of the best experts on this subject based on the ideXlab platform.
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critical Elastic Coefficient of liquid crystals and hysteresis
Communications in Mathematical Physics, 2008Co-Authors: Xingbin PanAbstract:P. G. de Gennes predicted the analogies between the effect of the Elastic Coefficients to liquid crystals and the effect of applied magnetic fields to superconductors, and predicted that all Elastic Coefficients diverge to infinity at smectic-C to nematic transition. One would expect quantitative comparison in the analogies. In the case of equal Elastic Coefficients (K1 = K2 = K3 = K), we define the critical value Kc of the Elastic Coefficients and make comparison of it with the upper critical magnetic field HC3 for type II superconductors. We classify the smectic liquid crystals into subcritical, critical and supercritical cases according to the Ginzburg-Landau parameter κ, the wave number q and the boundary value of the director at the surface. We show that in the subcritical case the liquid crystal does not undergo phase transition; and in the supercritical case both phase transition and hysteresis occur. The prediction of de Gennes is true in the critical case where μπ(u0, q) = κ2 and Kc = + ∞.
Francoise Peyrin - One of the best experts on this subject based on the ideXlab platform.
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quantification of nonlinear Elasticity for the evaluation of submillimeter crack length in cortical bone
Journal of The Mechanical Behavior of Biomedical Materials, 2015Co-Authors: Sylvain Haupert, Francoise Peyrin, Sandra Guerard, David Mitton, Pascal LaugierAbstract:The objective of this study was to investigate the sensitivity of the nonlinear Elastic properties of cortical bone to the presence of a single submillimetric crack. Nonlinear Elasticity was measured by nonlinear resonant ultrasound spectroscopy (NRUS) in 14 human cortical bone specimens. The specimens were parallelepiped beams (50×2×2 mm3). A central notch of 500 µm was made to control crack initiation and propagation during four-point bending. The nonlinear hysteretic Elastic and dissipative parameters αf and αQ, and Young׳s modulus Eus were measured in dry condition for undamaged (control) specimens and in dry and wet conditions for damaged specimens. The length of the crack was assessed using synchrotron radiation micro-computed tomography (SR-μCT) with a voxel size of 1.4 μm. The initial values of αf, measured on the intact specimens, were remarkably similar for all the specimens (αf =−5.5±1.5). After crack propagation, the nonlinear Elastic Coefficient αf increased significantly (p<0.006), with values ranging from −4.0 to –296.7. Conversely, no significant variation was observed for αQ and Eus. A more pronounced nonlinear Elastic behavior was observed in hydrated specimens compared to dry specimens (p<0.001) after propagation of a single submillimetric crack. The nonlinear Elastic parameter αf was found to be significantly correlated to the crack length both in dry (R=0.79, p<0.01) and wet (R=0.84, p<0.005) conditions. Altogether these results show that nonlinear Elasticity assessed by NRUS is sensitive to a single submillimetric crack induced mechanically and suggest that the humidity must be strictly controlled during measurements.
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determination of the heterogeneous anisotropic Elastic properties of human femoral bone from nanoscopic to organ scale
Journal of Biomechanics, 2010Co-Authors: Vittorio Sansalone, Francoise Peyrin, Salah Naili, Valerie Bousson, C Bergot, J Zarka, Jeandenis Laredo, Guillaume HaiatAbstract:Cortical bone is a multiscale composite material. Its Elastic properties are anisotropic and heterogeneous across its cross-section, due to endosteal bone resorption which might affect bone strength. The aim of this paper was to describe a homogenization method leading to the estimation of the variation of the Elastic Coefficients across the bone cross-section and along the bone longitudinal axis. The method uses the spatial variations of bone porosity and of the degree of mineralization of the bone matrix (DMB) obtained from the analysis of 3-D synchrotron micro-computed tomography images. For all three scales considered (the foam (100 nm), the ultrastructure (5 mu m) and the mesoscale (500 mu m)), the Elastic Coefficients were determined using the Eshelby's inclusion problem. DMB values were used at the scale of the foam. Collagen was introduced at the scale of the ultrastructure and bone porosity was introduced at the mesoscale. The pores were considered as parallel cylinders oriented along the bone axis. Each Elastic Coefficient was computed for different regions of interest, allowing an estimation of its variations across the bone cross-section and along the bone longitudinal axis. The method was applied to a human femoral neck bone specimen, which is a site of osteoporotic fracture. The computed Elastic Coefficients for cortical bone were in good agreement with experimental results, but some discrepancies were obtained in the endosteal part (trabecular bone). These results highlight the importance of accounting for the heterogeneity of cortical bone properties across bone cross-section and along bone longitudinal axis. (C) 2010 Elsevier Ltd. All rights reserved.
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variations of microstructure mineral density and tissue Elasticity in b6 c3h mice
Bone, 2007Co-Authors: Kay Raum, Tobias Hofmann, Ingrid Leguerney, Amena Saied, Francoise Peyrin, Laurence Vico, Pascal LaugierAbstract:200-MHz scanning acoustic microscopy (SAM) and synchrotron radiation μCT (SR-μCT) were used to assess microstructural parameters, acoustic impedance Z and tissue degree of mineralization of bone (DMB) in site-matched regions of interest in femoral bone of two inbred strains. Transverse femoral sections taken from 5 C57BL/6J@Ico (B6) and 5 C3H/HeJ@Ico (C3H) mice (5.5 months old) were explored. Mass density ρ, Elastic Coefficient c11 and Young's modulus E1 were locally derived in the distal epiphysis, distal metaphysis for trabecular bone and mid-diaphysis for cortical bone using a rule-of-mixture model. Structural parameter estimations obtained from X-ray tomographic and acoustic images were almost identical. Both strains had the same bone diameter, but the C3H mice had greater cortical thickness and smaller cancellous diameter than did B6 mice. The average DMB and impedance values were in the range between 1.13 and 1.33 g cm− 3 and 5.8 and 7.8 Mrayl, respectively. All tissue parameters were lower in B6 mice than in C3H mice. However, interstrain differences of DMB were much less (up to 3.8%) than differences of Z (up to 13.2%). SAM and SR-μCT fulfill the requirement for a simultaneous evaluation of cortical bone microstructure and material properties at the tissue level. However, SAM provides a quantitative estimate of Elastic properties at the tissue level that cannot be captured by SR-μCT. The strong differences in the measured acoustic impedances among the two inbred strains indicate that the impedance is a good parameter to detect genetic variations of the skeletal phenotype in small animal models.