microCT Scan Data Research Articles

Investigating the relationship between cranial bone thickness and diploic channels: A first comparison between fossil Homo sapiens and Homo neanderthalensis.

Diploic veins are part of the circulatory system of the head. They transport venous blood and cerebrospinal fluid and are housed in diploic channels (DCs). DCs are highly variable in terms of their position, extension, and size. These parameters were hypothesized to be related to the variations in cranial vault thickness (CVT). For the first time, we analyzed the spatial relationship between CVT and DCs in a sample of eight H. neanderthalensis and H. sapiens cranial fossils. Using micro-CT scanning data, we constructed color maps of the CVT and visually inspected whether the regional thickness variation was associated with the morphology and distribution of the DC branches. The results showed that when regional bone thickness was below a certain threshold, no DCs or scattered small DC branches were present. Larger DC branches appeared only when the thickness exceeded the threshold. However, once the threshold was reached, further increases in thickness no longer resulted in more or larger DCs. This study also found that our sample of H. neanderthalensis and H. sapiens have different distribution patterns in thin areas, which may affect how their DCs connect with different branches of the middle meningeal vessels. This preliminary study provides evidence for the discussion on the interaction between the cranium, brain, and blood vessels. Future research should include more hominin fossils to better document the variation within each species and possible evolutionary trends among hominin lineages.

On the dentition, tooth replacement, and taxonomic status of Charruodon tetracuspidatus Abdala & Ribeiro,2000: A bizarre cynodont from the middle upper Triassic of southern Brazil.

Among the living tetrapods, mammals present a unique tooth replacement pattern, diphyodonty. Therefore, studying the dentition of mammalian ancestors is relevant to a better understanding of how this remarkable feature evolved. However, little is known about the postcanine tooth replacement pattern among Triassic cynodonts. Here, we applied the nondestructive method of microcomputed tomography (microCT) to analyze the dentition of the enigmatic Upper Triassic sectorial-toothed cynodont Charruodon tetracuspidatus (MCP 3934 PV, holotype) from the Candelaria Sequence, Santa Maria Supersequence, Brazil. The microCT-scan data allowed visualization of the replacement dentition and roots of the functional teeth, which provided information to inform interpretations of the ontogenetic stage and taxonomy of the species. A combination of dental and mandibular traits, as well as the small size of the specimen MCP 3934 PV, suggest an early ontogenetic stage. Additionally, the specimen could potentially be an ontogenetically immature form of another taxon, or a yet unknown species of probainognathian cynodont. Therefore, Charruodon tetracuspidatus is here designated as a nomen dubium, given the challenges of maintaining the species as valid.

A new lizard-like reptile with unusual mandibular neurovasculature from the Upper Triassic of Virginia

ABSTRACT Here, we report a new small-bodied reptile taxon, Idiosaura virginiensis gen. et sp. nov., from the Upper Triassic (Carnian) Vinita Formation of the Richmond basin (Newark Supergroup) in east-central Virginia, U.S.A. The material consists of a fragmentary dentary bearing numerous tall cylindrical teeth implanted in a pleurodont fashion into spongy alveolar tissue. Micro-CT scan data reveal an unusual and complex network of interconnected neurovascular canals within the dentary with connections to the alveolar tissue and pulp cavities of the teeth. The external anatomy of the dentary is consistent with that of Triassic kuehneosaurid reptiles, suggesting affinities to that group; the results of a phylogenetic analysis were inconclusive but do not exclude kuehneosaurid relationships. Alongside the recently described Micromenodon pitti (Rhynchocephalia) and Vinitasaura lizae (Lepidosauromorpha), the new taxon adds to the relatively diverse assemblage of small-bodied reptiles known from the Tomahawk microvertebrate bonebed (USNM locality 39981). Relative tooth complexities of I. virginiensis and V. lizae were analyzed using the Orientation Patch Count Rotated method, and results suggest that the rise of lepidosauromorph ecomorphologies specializing for feeding on invertebrates occurred in Triassic communities alongside non-lepidosauromorph taxa with similar mandibulo-dental features, as in kuehneosaurs.

Theoretical and Experimental Analyses on the Sound Absorption Coefficient of Rice and Buckwheat Husks Based on Micro-CT Scan Data.

In this study, the sound absorption coefficients of rice and buckwheat husks were estimated. Computed tomography (CT) images were processed to determine the circumference and surface area of voids in the granular material, and the normal incident sound absorption coefficients were derived. In addition, the tortuosity, which expresses the complexity of the sound wave propagation through the structure, was measured for each material. The theoretical sound absorption coefficients were then compared to the measured sound absorption coefficients with and without consideration of the tortuosity. A correction factor was used to bring the surface area of the granular material closer to the actual surface area and observed that the tortuosity obtained theoretical values that matched the trend of the measured values. These results indicate that using CT images to estimate the sound absorption coefficient is a viable approach.

An FFT-based method for estimating the in-plane elastic properties of honeycomb considering geometric imperfections at large elastic deformation

The geometric imperfections in honeycomb cells inevitably arise during the manufacturing process and can affect the honeycomb’s mechanical performance. Hence, it is critical to identify and quantify the geometric imperfections and characterize the effects of these imperfections on the effective mechanical properties of honeycomb. In this study, the geometric imperfections inside the honeycomb were identified from micro-CT scan data. Using the obtained geometric topology, a Fast Fourier Transform (FFT) based method was employed in combination with the composite pixel method to predict the effective in-plane elastic properties of honeycomb at large elastic deformations. The results of the nonlinear homogenized prediction were compared with the experimental data and the prediction values from analytical models to investigate the effects of geometric imperfections. It was found that the predictions from the FFT-based method agreed well with the experimental results. However, the predictions from the analytical models significantly overestimated or underestimated the elastic properties, indicating that the geometric imperfections inside the honeycomb significantly influence its in-plane elastic properties.

Revisions to the Eocene carpoflora of Anjou, western France, with new data from X-ray tomography

ABSTRACT Selected fruits and seeds preserved as molds and casts in sediments from the Anjou flora of Maine-et-Loire have been reexamined with the aid of X-ray tomography. Virtual casts and surface renderings from micro-CT scanning data reveal external and internal morphological characters that were not visible by standard reflected light microscopy. Application of this methodology leads to a revision of the fruit formerly treated as Juglandicarya. It is a 5-valved capsule of likely sapindalean affinity, and is placed in Vaudoisia gruetii (Vaudois-Miéja) gen. et. comb. nov. A seed with the characteristic rumination of Anonaspermum is also recognized for the first time, as are capsular fruits of Ericaceae. We note that many disseminules are hidden from optical viewing because they are buried within the hand samples. A more extensive micro-CT scan investigation of more samples, including those showing only fossil leaf impressions at the surface, may be expected to yield a wealth of new information on this classic flora.

New observations on test architecture and construction of Jullienella foetida Schlumberger, 1890, the largest shallow-water agglutinated foraminifer in modern oceans.

We present new observations on Jullienella foetida Schlumberger, 1890, a giant agglutinated foraminifer with a leaf- or fan-like test reaching a maximum dimension of 14 cm, that is common on some parts of the west African continental shelf. The test wall comprises a smooth, outer veneer of small (<10 µm) mineral grains that overlies the much thicker inner layer, which has a porous structure and is composed of grains measuring several hundreds of microns in size. Micro-CT scans suggest that much of the test interior is filled with cytoplasm, while X-ray micrographs reveal an elaborate system of radiating internal partitions that probably serve to channel cytoplasmic flow and strengthen the test. Jullienella foetida resembles some xenophyophores (giant deep-sea foraminifera) in terms of test size and morphology, but lacks their distinctive internal organization; the similarities are therefore likely to be convergent. Based on micro-CT scan data, we calculated an individual cytoplasmic biomass of 3.65 mg wet weight for one specimen. When combined with literature records of seafloor coverage, this yielded an estimate of >7.0 g wet weight m−2 for the seafloor biomass of J. foetida in areas where it is particularly abundant. The relatively restricted distribution of this species off the north-west African coast at depths above 100 m is probably related to the elevated, upwelling-related surface productivity along this margin, which provides enough food to sustain this high biomass. This remarkable species appears to play an important, perhaps keystone, role in benthic ecosystems where it is abundant, providing the only common hard substrate on which sessile organisms can settle.

A micro-CT based study of molar enamel thickness and its distribution pattern in Late Miocene Lufengpithecus lufengensis from Yunnan in Southwestern China

ABSTRACT Molar enamel thickness and distribution pattern inform on the functional and dietary adaptation of extant and fossil primates. However, no systematic analysis of enamel thickness has been conducted on Lufengpithecus, a large-bodied fossil hominoid that lived in Southwest China during the late Miocene. In this study, we quantify two-dimensional (2D) enamel thickness and distribution of 68 lightly worn molars of Lufengpithecus (L.) lufengensis using micro-CT scanning data and compare it with modern humans, extant great apes, and fossil hominoids. The results indicate L. lufengensis has relatively thick enamel. It is slightly thicker than extant Pongo and comparable to some thick-enamel fossil pongines, but thinner than modern humans and most fossil hominins. The enamel distribution of L. lufengensis is distinctively unbalanced with relatively more enamel deposited on the cuspal region than the basal region in the molar crown, different from that found in modern humans and extant great apes. Concerning its palaeoecological and functional adaptations, we suggest that the features of thick-enamel and unbalanced distribution pattern in L. lufengensis is related to its adaptation to tough food and broader diets in a seasonal subtropical habitat.

Spinal Motion Segments — II: Tuning and Optimisation for Biofidelic Performance

Most commercially available spine analogues are not intended for biomechanical testing, and the few that are suitable for using in conjunction with implants and devices to allow a hands-on practice on operative procedures are very expensive and still none of these offers patient-specific analogues that can be accessed within reasonable time and price range. Man-made spine analogues would also avoid the ethical restrictions surrounding the use of biological specimens and complications arising from their inherent biological variability. Here we sought to improve the biofidelity and accuracy of a patient-specific motion segment analogue that we presented recently. These models were made by acrylonitrile butadiene styrene (ABS) in 3D printing of porcine spine segments (T12−L5) from microCT scan data, and were tested in axial loading at 0.6 mm·min−1 (strain rate range 6×10−4 s−1–10×10−4 s−1). In this paper we have sought to improve the biofidelity of these analogue models by concentrating in improving the two most critical aspects of the mechanical behaviour: the material used for the intervertebral disc and the influence of the facet joints. The deformations were followed by use of Digital Image Correlation (DIC) and consequently different scanning resolutions and data acquisition techniques were also explored and compared to determine their effect. We found that the selection of an appropriate intervertebral disc simulant (PT Flex 85) achieved a realistic force/displacement response and also that the facet joints play a key role in achieving a biofidelic behaviour for the entire motion segment. We have therefore overall confirmed the feasibility of producing, by rapid and inexpensive 3D-printing methods, high-quality patient-specific spine analogue models suitable for biomechanical testing and practice.

Systematics of the ant genus Proceratium Roger (Hymenoptera, Formicidae, Proceratiinae) in China - with descriptions of three new species based on micro-CT enhanced next-generation-morphology.

The genus Proceratium Roger, 1863 contains cryptic, subterranean ants that are seldom sampled and rare in natural history collections. Furthermore, most Proceratium specimens are extremely hairy and, due to their enlarged and curved gaster, often mounted suboptimally. As a consequence, the poorly observable physical characteristics of the material and its scarcity result in a rather challenging alpha taxonomy of this group. In this study, the taxonomy of the Chinese Proceratium fauna is reviewed and updated by combining examinations of traditional light microscopy with x-ray microtomography (micro-CT). Based on micro-CT scans of seven out of eight species, virtual 3D surface models were generated that permit in-depth comparative analyses of specimen morphology in order to overcome the difficulties to examine physical material of Proceratium. Eight Chinese species are recognized, of which three are newly described: Proceratium bruelheidei Staab, Xu & Hita Garcia, sp. n. and P. kepingmai sp. n. belong to the P. itoi clade and have been collected in the subtropical forests of southeast China, whereas P. shohei sp. n. belongs to the P. stictum clade and it is only known from a tropical forest of Yunnan Province. Proceratium nujiangense Xu, 2006 syn. n. is proposed as a junior synonym of P. zhaoi Xu, 2000. These taxonomic acts raise the number of known Chinese Proceratium species to eight. In order to integrate the new species into the existing taxonomic system and to facilitate identifications, an illustrated key to the worker caste of all Chinese species is provided, supplemented by species accounts with high-resolution montage images and still images of volume renderings of 3D models based on micro-CT. Moreover, cybertype datasets are provided for the new species, as well as digital datasets for the remaining species that include the raw micro-CT scan data, 3D surface models, 3D rotation videos, and all light photography and micro-CT still images. These datasets are available online (Dryad, Staab et al. 2018, http://dx.doi.org/10.5061/dryad.h6j0g4p).

The nasal salt gland of extant birds: anatomical structure and its relevance for inferring the behavior and habitat preferences of extinct birds

The kidneys of extant sauropsids (birds, crocodylians, turtles, lepidosaurs) tend to be less efficient at removing excess salt from the blood than are those of mammals, and consequently, sites of extrarenal salt excretion are common in sauropsids. In birds, the nasal gland is involved with concentrating and excreting salt from the blood. In many marine birds (e.g., charadriiforms, procellariiforms), the nasal gland is hypertrophied and occupies a supraorbital position, but other positions are known in birds, such as within the orbit (e.g., suliforms). The basic physiology of avian nasal salt glands has been well‐understood for generations, but the detailed anatomy, particularly with regard to its osteology, is poorly documented. We present the results of our preliminary survey of nasal gland structure in birds to better resolve the osteological correlates of the gland, its ducts, and its vascular supply. The resulting osteological correlates (e.g., bony fossa, supraorbital process of the lacrimal, foramina/grooves for ducts) allow a more rigorous and informed assessment of the presence, position, and size of the nasal gland in extinct birds, potentially allowing rough assessments of salt loads and hence habitat preferences (e.g., marine vs. terrestrial). The extant studies emphasize marine and aquatic birds (e.g., albatrosses, shearwaters, gulls, gannets, cormorants, anseriforms), among others, such as, non‐marine outgroups (e.g., ostrich), drawing on the following anatomical approaches: (1) gross dissection, (2) diceCT (iodine enhanced microCT), and (3) radio‐opaque vascular injection followed by microCT. These studies allow not only detailed information about the relevant soft tissues and their osteological correlates, but also permit quantification of gland volumes and other metrics for comparative analysis. These extant studies shed new light on the interpretation of the nasal glands of extinct birds. Study of original fossil material and microCT scan data provide more refined information on the nasal glands of the Cretaceous marine toothed birds Hesperornis and Ichthyornis. The flightless diver Hesperornis had enormous nasal glands, suggesting that it was forced to consume seawater exclusively, whereas the volant and hence more vagile Ichthyornis had smaller salt glands suggesting that it perhaps also had access to fresh water sources. The Paleogene anseriform bird Presbyornis, typically regarded as inhabiting saline soda lakes, also was sampled and provides new evidence for a modest nasal salt gland.Support or Funding InformationUS National Science Foundation (IOB‐0517257, IOS‐1050154, IOS‐1456503), the Ohio University Honors Tutorial College, and the Ohio University Heritage College of Osteopathic Medicine

Efficient digitalization method for dental restorations using micro-CT data

The objective of this study was to demonstrate the feasibility of using micro-CT scan of dental impressions for fabricating dental restorations and to compare the dimensional accuracy of dental models generated from various methods. The key idea of the proposed protocol is that dental impression of patients can be accurately digitized by micro-CT scan and that one can make digital cast model from micro-CT data directly. As air regions of the micro-CT scan data of dental impression are equivalent to the real teeth and surrounding structures, one can segment the air regions and fabricate digital cast model in the STL format out of them. The proposed method was validated by a phantom study using a typodont with prepared teeth. Actual measurement and deviation map analysis were performed after acquiring digital cast models for each restoration methods. Comparisons of the milled restorations were also performed by placing them on the prepared teeth of typodont. The results demonstrated that an efficient fabrication of precise dental restoration is achievable by use of the proposed method.

An updated description of the osteology of the pancake tortoise Malacochersus tornieri (Testudines: Testudinidae) with special focus on intraspecific variation.

Exceptional variability in the shell of the pancake tortoise Malacochersus tornieri, both in the keratinous surficial scutes and the underlying bones, in addition to its remarkably fenestrated bony shell are unique among tortoises. Based on 14 individuals of different sizes and ages, the observed variation in M. tornieri was described in detail, with additional notes on the typically testudinid skull, inner ear and brain endocast using microCT-scan data, as well as the limbs. Similar degrees of variation have not yet been described in any other extant turtle species and therefore seem notable in M. tornieri, and might be related to the species' unique lifestyle. Within the carapace, the peripherals and suprapygals are most variable in number. Furthermore, different combinations of peripherals are participating in the central plastral fontanelle and in some individuals additional bones take part in the formation of the plastron. J. Morphol. 278:321-333, 2017. © 2017 Wiley Periodicals, Inc.

Patterns of postnatal ontogeny of the skull and lower jaw of snakes as revealed by micro-CT scan data and three-dimensional geometric morphometrics.

We compared the head skeleton (skull and lower jaw) of juvenile and adult specimens of five snake species [Anilios (=Ramphotyphlops) bicolor, Cylindrophis ruffus, Aspidites melanocephalus, Acrochordus arafurae, and Notechis scutatus] and two lizard outgroups (Ctenophorus decresii, Varanus gilleni). All major ontogenetic changes observed were documented both qualitatively and quantitatively. Qualitative comparisons were based on high-resolution micro-CT scanning of the specimens, and detailed quantitative analyses were performed using three-dimensional geometric morphometrics. Two sets of landmarks were used, one for accurate representation of the intraspecific transformations of each skull and jaw configuration, and the other for comparison between taxa. Our results document the ontogenetic elaboration of crests and processes for muscle attachment (especially for cervical and adductor muscles); negative allometry in the braincase of all taxa; approximately isometric growth of the snout of all taxa except Varanus and Anilios (positively allometric); and positive allometry in the quadrates of the macrostomatan snakes Aspidites, Acrochordus and Notechis, but also, surprisingly, in the iguanian lizard Ctenophorus. Ontogenetic trajectories from principal component analysis provide evidence for paedomorphosis in Anilios and peramorphosis in Acrochordus. Some primitive (lizard-like) features are described for the first time in the juvenile Cylindrophis. Two distinct developmental trajectories for the achievement of the macrostomatan (large-gaped) condition in adult snakes are documented, driven either by positive allometry of supratemporal and quadrate (in pythons), or of quadrate alone (in sampled caenophidians); this is consistent with hypothesised homoplasy in this adaptive complex. Certain traits (e.g. shape of coronoid process, marginal tooth counts) are more stable throughout postnatal ontogeny than others (e.g. basisphenoid keel), with implications for their reliability as phylogenetic characters.

Validation experiments on finite element models of an ostrich (Struthio camelus) cranium.

The first finite element (FE) validation of a complete avian cranium was performed on an extant palaeognath, the ostrich (Struthio camelus). Ex-vivo strains were collected from the cranial bone and rhamphotheca. These experimental strains were then compared to convergence tested, specimen-specific finite element (FE) models. The FE models contained segmented cortical and trabecular bone, sutures and the keratinous rhamphotheca as identified from micro-CT scan data. Each of these individual materials was assigned isotropic material properties either from the literature or from nanoindentation, and the FE models compared to the ex-vivo results. The FE models generally replicate the location of peak strains and reflect the correct mode of deformation in the rostral region. The models are too stiff in regions of experimentally recorded high strain and too elastic in regions of low experimentally recorded low strain. The mode of deformation in the low strain neurocranial region is not replicated by the FE models, and although the models replicate strain orientations to within 10° in some regions, in most regions the correlation is not strong. Cranial sutures, as has previously been found in other taxa, are important for modifying both strain magnitude and strain patterns across the entire skull, but especially between opposing the sutural junctions. Experimentally, we find that the strains on the surface of the rhamphotheca are much lower than those found on nearby bone. The FE models produce much higher principal strains despite similar strain ratios across the entirety of the rhamphotheca. This study emphasises the importance of attempting to validate FE models, modelling sutures and rhamphothecae in birds, and shows that whilst location of peak strain and patterns of deformation can be modelled, replicating experimental data in digital models of avian crania remains problematic.

Geometric mouse variation: Implications to the axial ulnar loading protocol and animal specific calibration

Large variations in axial ulnar load strain calibration results suggest that animal-specific calibrations may be necessary. However, the optimal set of geometric measures for performing an animal-specific calibration are not known, potentially as a result of confounding effects associated with experimentally introduced variation. The purpose of this study was to characterize the inherent variability of ulnar geometric measures known to influence periosteal midshaft strain during axial ulnar exogenous loading, and to further quantify the relationship between the variance of those geometric measures and periosteal strain during axial loading. Thirty-nine right mouse forelimbs were scanned with microCT. Seven geometric measures that influence periosteal strain resulting from a combined axial and bending loading were computed and used to estimate animal-specific strains on the periosteal midshaft. Animal specific strains were estimated using a theoretical model based on the generalized flexure formula. The predicted mean and standard deviation of the simulated midshaft strain gauge measurement resulting from the inter-animal geometric differences was −985±148με/N. The complete beam bending term associated with bending about the Imin axis accounted for 89% of the variance and reduced the residual RMSE to 50.4με. Eccentricity associated with the axial loading contributed a substantial portion of variation to the computed strain suggesting that calibration procedures to account for animal differences should incorporate that variable. The method developed in this study provides a relatively simple procedure for computing animal-specific strains using microCT scan data, without the need of a load/strain calibration study or computationally intensive finite element models.

Contrast Enhancement of MicroCT Scans to Aid 3D Modelling of Carbon Fibre Fabric Composites

This paper presents a methodology for volume capture and rendering of plain weave and multi-layer fabric meso-architectures within a consolidated, cured laminate. Micro X-ray Computed Tomography (MicroCT) is an excellent tool for the non-destructive visualisation of material microstructures however the contrast between tows and resin is poor for carbon fibre composites. Firstly, this paper demonstrates techniques to improve the contrast of the microCT images by introducing higher density materials such as gold, iodine and glass into the fabric. Two approaches were demonstrated to be effective for enhancing the differentiation between the tows in the reconstructed microCT visualisations. Secondly, a method of generating three-dimensional volume models of woven composites using microCT scan data is discussed. The process of generating a model is explained from initial manufacture with the aid of an example plain weave fabric. These methods are to be used in the finite element modelling of three-dimensional fabric preforms in future work.

Deriving tissue density and elastic modulus from microCT bone scans

Tissue level density and elastic modulus are intrinsic properties that can be used to quantify bone material and analyses incorporating those quantities have been used to evaluate bone on a macroscopic scale. Micro-computed tomography (microCT) technology has been used to construct tissue level finite element models to simulate macroscopic fracture strength, however, a single method for assigning voxel-specific tissue density and elastic modulus based on those data has not been universally accepted. One method prevalent in the literature utilizes an empirical relationship that derives tissue stiffness as a function of bone calcium content weight fraction. To derive calcium content weight fraction from microCT scans, a measure of tissue density is required and a constant value is traditionally used. However, experimental data suggest a non-trivial amount of tissue heterogeneity suggesting a constant tissue density may not be appropriate. A theoretical derivation for determining the relationship between voxel-specific tissue density and microCT scan data (i.e., microCT derived tissue mineral density (TMD), mgHA/cm(3)) and bone constituent properties is proposed. Constant model parameters used in the derivation include the density of water, ash, and organics (i.e., bone constituents) and the volume fraction of the organics constituent. The effect of incorporating the theoretically derived tissue density (instead of a constant value) in determining voxel-specific elastic modulus resulted in a maximum observed increase of 12GPa (5.9GPa versus 17.9GPa, for the constant value and derived tissue density formulations, respectively) for a measured TMD of 1.02gHA/cm(3). Average and bounding quantities for the four constant model parameters were defined from the literature and the influence of those values on the derived tissue density and elastic modulus relationships were also evaluated. The theoretical relationships of tissue density and elastic modulus, with the average constant model parameters applied, were consistent with previously published empirical relationships derived from experimental data. Tissue density as a function of microCT TMD was formulated as a linear relationship and the density of water and ash was shown to solely influence the proportionality (i.e., slope) between those values. The density of water and organics (i.e., collagen) and the volume fraction of the organics constituent were shown to influence the constant offset (intercept) between tissue density and TMD with no influence from ash density. Incorporating tissue density heterogeneity into the derivation of elastic modulus resulted in a significant increase in predicted modulus (for microCT TMD ranges observed for healthy tissue) as compared to when a constant tissue density was used. The presented approach provides a novel method for deriving tissue-level bone material properties and quantifies the effect of assuming tissue homogeneity when calculating elastic modulus (when using a prevalent method in the literature) from microCT scan data.

Detecting and Tracking Changes of Morphologies and Mechanical Characteristics in the Lumbar Vertebrae of OVX Rats Using RP Technique and Micro-FE Method

In the present study, changes of morphologies and mechanical characteristics in the lumbar vertebrae of the ovariectomised (OVX) rats were investigated and analyzed by Finite Element (FE) and Rapid-Prototyped (RP) models based on micro-computed tomography (micro-CT). In previous researches, there were many studies about morphology such as bone mineral density and trabecular microstructure. However, detecting and tracking local changes were few in the trabecular and cortical bone of the lumbar vertebrae for the OVX rats. Experimental and simulated studies were used to investigate mechanical characteristics of the lumbar vertebral bones for the OVX rats. Three dimensional (3D) geometries of the models (RP and FE models), generated from in-vivo micro-CT scan data, were obtained from the 4th lumbar of the OVX rats. Three specimens (whole vertebral, trabecular and cortical bone models) were generated and analyzed in the simulated compression tests. For further verification, the experimental compression test for RP models ‘instead of real bone specimens’ was performed to indirectly validate the results of the simulated compression test for the FE models. The results were similar to those of the compression test simulated by micro-FE analysis. The present study showed the efficiency of the combined method (FE and RP techniques based on in-vivo micro-CT) as a nondestructive evaluation.