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The geometric and transport properties of trabecular bone are of particular interest for medical engineers active in orthopaedic applications and more specifically in hard tissue implantations. This article resorts to computational methods to provide some understanding of the geometric and transport properties of vertebral trabecular bone. A fuzzy distance transform algorithm was used for geometric analysis on the pore scale, and a lattice Boltzmann method (LBM) for the simulation of flow on the same scale. The transport properties of bone including the pressure drop, elongation, and shear component of dissipated energy, and the tortuosity of the bone geometry were extracted from the results of the LBM flow simulations. Whenever suitable, dimensionless numbers were used for the analysis of the data. The average pore size and distribution of the bone were found to be 746 mm and between 75 and 2940 mm, respectively. The permeability of the flow in the cavities of the specific bone sample was found to be 5.0561028 m 2 for the superior-inferior direction which was by a factor of 1.5-1.7 higher than the permeability in the other two anatomical directions (anterior-posterior). These findings are consistent with experimental results found 3 years prior independently. Tortuosity values approached 1.05 for the superior-inferior direction, and 1.13 and 1.11 for the other two perpendicular directions. The low tortuosities result mainly from the large bone porosity of 0.92. The flow on the pore scale seems to be shear dominated but 30 per cent of the energy dissipation was because of elongational effects. The converging and diverging geometry of the bone explains the significant elongation and deformation of the fluid elements. The transition from creeping flow (the Darcy regime), which is of interest to vertebral augmentation and this study, to the laminar region with significant inertia effects took place at a Reynolds number of about 1-10, as usual for porous media. Finally, the authors wish to advise the readers on the significant computational requirements to be allocated to such a virtual test bench.

This paper presents a summary of recent research activities carried out at our laboratory in the field of Infrared Thermography for Nondestructive Evaluation (TNDE). First, we explore the latest developments in signal improvement. We describe three approaches: multiple pulse stimulation [1]; the use of Synthetic Data for de-noising of the signal [2]; and a new approach derived from the Fourier diffusion equation called the Differentiated Absolute Contrast method (DAC) [3]. Secondly, we examine the advances carried out in inverse solutions. We describe the use of the Wavelet Transform [4] to manage pulsed thermographic data, and we present a summary on Neural Networks for TNDE [5]. Finally, we look at the problem of complex geometry inspection. In this case, due to surface shape, heat variations might be incorrectly identified as flaws. We describe the Shape-from-Heating approach [6] and we propose some potential research avenues to deal with this problem.

Investigations have been carried out with the goal of assessing the trabecular bone thickness of biological samples using images obtained by micro-computed tomography and magnetic resonance imaging. There is no conventional definition of trabecular bone thickness, and many methods may be involved in determining it. However, the results of the available algorithms or software packages differ considerably from each other. This paper determines trabecular bone thickness on the basis of several algorithms. A deep understanding of the performance of different methods is achieved by studying pseudo-three-dimensional images of both geometrical models of well-defined thickness and real bone samples with different bone densities. The models facilitate comparisons between the algorithms or software packages. Comparison of the results obtained from these commercial software packages and other state-of-the-art algorithms shows that the thickness, spatial distribution, and shape of an object affect each result differently, but in a significant manner. This is primarily due to variations in the thresholding algorithms used to distinguish object area elements (pixels/voxels) from the background, or non-object, region. Additionally, the results show that the average difference in thickness measurements can vary by up to 102.34% for models and 46.49% for real bone samples. This data shows that the differences in measurements of the trabecular bone thickness due simply to the algorithm involved are remarkable. Therefore, biomedical engineers and scientists should be careful to select the algorithm that is most compatible with their specific application.Cetteétude aété menée avec l'intention d'évaluer l'épaisseur d'os trabéculaireà partir d'échantillons acquis par micro tomographie et résonance magnétique. Il n'existe pas de définition conventionnelle de l'épaisseur de l'os trabéculaire. Aussi, plusieurs approches ontété envisagées en vue de caractériser cette dernière. Cependant il est apparu que les résultats obtenus différaient considérablement suivant les algorithmes ou logiciels commerciaux utilisés. Uneétude plus approfondie a doncété menée afin de déterminer les performances de chacune des méthodes, ceci au moyen d'étude faisant intervenir des modèles tridimensionnels numériques auxépaisseurs connues et d'os de différentes densités osseuses. Le recoursà l'utilisation de modèles a facilité la comparaison des différents algorithmes et logiciels. Cette comparaison a révélé que l'épaisseur, la répartition spatiale et la forme d'un objet affectaient de manière significative les résultats obtenus. Ceci fut principalement dûà la capacité des différentes approchesà discriminer l'objet a analyser (pixel/voxel) de l'information non pertinente, c'est-à-dire le fond de l'image. En outre, les résultats ont montré que les mesures d'épaisseur avaient une erreur moyenne maximale de 102.34% pour les modèles numériques et de 46.49% pour les spécimens d'os. Ces données ont indiqué que les différences de mesure d'épaisseur en raison des algorit...

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