Micro‐CT versus synchrotron radiation phase contrast imaging of human cochlea

High‐resolution images of the cochlea are used to develop atlases to extract anatomical features from low‐resolution clinical computed tomography (CT) images. We compare visualization and contrast of conventional absorption‐based micro‐CT to synchrotron radiation phase contrast imaging (SR‐PCI) images of whole unstained, nondecalcified human cochleae. Three cadaveric cochleae were imaged using SR‐PCI and micro‐CT. Images were visually compared and contrast‐to‐noise ratios (CNRs) were computed from n = 27 regions‐of‐interest (enclosing soft tissue) for quantitative comparisons. Three‐dimensional (3D) models of cochlear internal structures were constructed from SR‐PCI images using a semiautomatic segmentation method. SR‐PCI images provided superior visualization of soft tissue microstructures over conventional micro‐CT images. CNR improved from 7.5 ± 2.5 in micro‐CT images to 18.0 ± 4.3 in SR‐PCI images (p < 0.0001). The semiautomatic segmentations yielded accurate reconstructions of 3D models of the intracochlear anatomy. The improved visualization, contrast and modelling achieved using SR‐PCI images are very promising for developing atlas‐based segmentation methods for postoperative evaluation of cochlear implant surgery.     

Effect of Reciproc blue,XP‐endo shaper,and WaveOne gold instruments on dentinal microcrack formation: A micro‐computed tomographic evaluation

The purpose of this study was to evaluate and compare the effect of Reciproc Blue (RPCB), XP‐endo Shaper (XPS), and WaveOne Gold (WOG) single‐files on dentinal microcrack formation using micro‐computed tomography (micro‐CT). Twenty‐four mesial roots (24 mesio‐buccal and 24 mesio‐lingual canals) of mandibular molar teeth were prepared using RPCB, XPS, and WOG files (n = 8/each group). The samples were scanned with micro‐CT in the pre‐ and post‐preparation. Then, before preparation and after preparation cross‐sectional images of the teeth were evaluated to detect the presence of microcracks. For each group, the number of microcracks was calculated as a percentage rate. The data were statistically analyzed using McNemar at 5% significance level (p < .05). Dentinal microcracks were observed in 25.99% (2,103 of 7,813), 31.99% (2,482 of 7,758), and 36.66% (2,836 of 7,731) of cross‐sectional images of the XPS, WOG, and RPCB groups, respectively. In all the groups, all the dentinal microcracks seen in the post‐treatment cross‐sectional images were present in the corresponding pre‐treatment images. Within the limitations of this study, the XPS, WOG, and RPCB files did not cause new dentinal microcrack formation or propagation of existing dentinal microcracks.     

Two‐photon laser scanning microscopy as a useful tool for imaging and evaluating macrophage‐, IL‐4 activated macrophage‐ and osteoclast‐based In Vitro degradation of beta‐tricalcium phosphate bone substitute material

Two‐photon microscopy is an innovative technology that has high potential to combine the examination of soft and hard tissues in vitro and in vivo. Calcium phosphates are widely used substitutes for bone tissue engineering, since they are degradable and consequently replaced by newly formed tissue. It is well known that osteoclasts are responsible for the resorption processes during bone remodelling. We hypothesize that also macrophages are actively involved in the resorption process of calcium phosphate scaffolds and addressed this question in in vitro culture systems by two‐photon laser scanning microscopy. Beta‐tricalcium phosphate specimens were incubated with (1) macrophages, (2) interleukin‐4 activated macrophages, and (3) osteoclasts for up to 21 days. Interestingly, macrophages degraded beta‐tricalcium phosphate specimens in an equivalent fashion compared to osteoclasts and significantly more than IL‐4 activated macrophages. An average of ～32% of the macrophages was partially filled with ceramic material while this was 18% for osteoclasts and 9% for IL‐4 activated macrophages. For the first time by applying two‐photon microscopy, our studies show the previously unrecognized potential of macrophages to phagocytose ceramic material, which is expected to have implication on osteoconductive scaffold design. Microsc. Res. Tech. 77:143–152, 2014. © 2013 Wiley Periodicals, Inc.     

Feasibility of detecting trabecular bone around percutaneous titanium implants in rabbits by in vivo microfocus computed tomography

Objectives: The goal of this study was to examine the feasibility of in vivo imaging of trabecular bone around titanium implants by means of microfocus computed tomography (micro‐CT) and the use of rabbits for this purpose. Materials and Methods: Ten male rabbits type Hollander, received a titanium implant (1.7 mm diameter and 10 mm length) in the trabecular bone of the left tibia. Seven weeks later a micro‐CT scan was taken. Four rabbits were used to monitor potential harmful effects from X‐ray absorption until 4 weeks after scanning. A second group of six rabbits was used for testing the hypothesis that a good correlation exists between in vivo micro‐CT images and histological images of trabecular bone around titanium implants. The six rabbits were scanned and sacrificed immediately. The tibias were extracted and submitted to standard histological procedures. This resulted in a total of 12 histological sections and their corresponding 12 micro‐CT images. Bone area measurements were performed at the left and right side of the implant in three regions: 0–500, 500–1000 and 1000–1500 μm distance from the implant interface. Intra‐class correlations (ICC) were calculated between both techniques. Results: The four rabbits did not show any sign of radiodermatitis 4 weeks after scanning. In the micro‐CT images of the group of six rabbits, trabeculae are visible, but not well defined, due to the presence of noise in the image. The ICC for the right implant side were 0.44 for zone 0–500 μm, 0.48 for zone 500–1000 μm and 0.40 for zone 1000–1500 μm. The ICC for the left implant side could not be calculated. Conclusion: A low agreement was found between the bone measurements from histology and in vivo micro‐CT images. The use of the in vivo micro‐CT for trabecular bone imaging around metallic implants should be restricted to track tendencies in follow‐up studies.     

Ossa cordis and os aorta in the one-humped camel: Computed tomography,light microscopy and morphometric analysis

The present study describes the morphological characteristics of the camel heart Ossa cordis, and os aorta using computed tomography soft tissue window (CT) alongside 3D render volume reconstructions and light microscopy. The current study techniques demonstrated the Ossa cordis and os aorta in the cardiac window with more precision than the black and white (ghost), and angiography images. Transverse and sagittal CT images additionally demonstrated the presence of Ossa cordis and os aorta. This study is the first to record two small Ossa cordis sinistrum and one os aorta in the camel heart, in addition to the more commonly observed singular, large, os cordis dextrum. The os cordis dextrum was always located in the upper part of the interventricular septum, near to its junction with the atrium, forming an elongated rectangular shape when observed transversally. The wider cranial part was composed from bone, whereas the caudal aspect was narrow and contained both bone and cartilage. Light microscopy identified that the os cordis dextrum consisted of trabecular bone, marrow spaces, and hyaline cartilage. Two Ossa cordis sinistrum were detected on the left side of the heart, one in the right fibrous ring and another in the interventricular septum, microscopy showed that both contained only trabecular bone with osteocytes, osteoblasts, and osteoclasts. At the level of ascending aorta, there was also trabecular bone containing osteocytes, an os aorta.     

Comparative study of decalcification versus nondecalcification for histological evaluation of one‐wall periodontal intrabony defects in dogs

Biological reactions between biomaterials and surrounding tissues, analyzed by histology, may be important predictors of clinical healing pattern and selection of slide preparation techniques requires a careful consideration regarding sample properties. In this study, we compared histology of bone specimens prepared with or without decalcification and performed histological and histomorphometrical assessments. For the histological evaluation, one‐wall intrabony defects were created around the mandibular molars of six adult dogs, filled with biphasic calcium phosphate, synthetic bone graft material/recombinant human bone morphogenic protein‐2, and healing pattern was histologically evaluated at 4 and 12 weeks. New bone formation in 5 × 4 × 4 mm defects and the length of new cementum, connective tissue attachments around the teeth and number of osteoclasts were measured by histomorphometric analysis. After decalcification, new cementum was easily observed and was significantly increased at week 4. In nondecalcified samples, significantly increased connective tissue attachments were seen at week 12. After 12 weeks, the number of countable multinucleated osteoclasts was significantly increased by 62% in nondecalcified versus calcified tissue sections (P = 0.030). Histomorphometric results may be significantly affected by histological preparation method and therefore, selecting the most appropriate histological preparation method is essential for reliable diagnosis and evaluation of bony samples in studies analyzing tissue regeneration. Microsc. Res. Tech. 78:94–104, 2015. © 2014 Wiley Periodicals, Inc.     

Evaluation of contrasting techniques for X‐ray imaging of velvet worms (Onychophora)

Non‐invasive imaging techniques like X‐ray computed tomography have become very popular in zoology, as they allow for simultaneous imaging of the internal and external morphology of organisms. Nevertheless, the effect of different staining approaches required for this method on samples lacking mineralized tissues, such as soft‐bodied invertebrates, remains understudied. Herein, we used synchrotron radiation‐based X‐ray micro‐computed tomography to compare the effects of commonly used contrasting approaches on onychophorans – soft‐bodied invertebrates important for studying animal evolution. Representatives of Euperipatoides rowelli were stained with osmium tetroxide (vapour or solution), ruthenium red, phosphotungstic acid, or iodine. Unstained specimens were imaged using both standard attenuation‐based and differential phase‐contrast setups to simulate analyses with museum material. Our comparative qualitative analyses of several tissue types demonstrate that osmium tetroxide provides the best overall tissue contrast in onychophorans, whereas the remaining staining agents rather favour the visualisation of specific tissues and/or structures. Quantitative analyses using signal‐to‐noise ratio measurements show that the level of image noise may vary according to the staining agent and scanning medium selected. Furthermore, box‐and‐whisker plots revealed substantial overlap in grey values among structures in all datasets, suggesting that a combination of semiautomatic and manual segmentation of structures is required for comprehensive 3D reconstructions of Onychophora, irrespective of the approach selected. Our results show that X‐ray micro‐computed tomography is a promising technique for studying onychophorans and, despite the benefits and disadvantages of different staining agents for specific tissues/structures, this method retrieves informative data that may eventually help address evolutionary questions long associated with Onychophora.     

Magnetosomal matrix: ultrafine structure may template biomineralization of magnetosomes

The organic matrix surrounding bullet‐shaped, cubo‐octahedral, D‐shaped, irregular arrowhead‐shaped, and truncated hexa‐octahedral magnetosomes was analysed in a variety of uncultured magnetotactic bacteria. The matrix was examined using low‐ (80 kV) and intermediate‐ (400 kV) voltage TEM. It encapsulated magnetosomes in dehydrated cells, ultraviolet‐B‐irradiated dehydrated cells and stained resin‐embedded fixed cells, so the apparent structure of the matrix does not appear to be an artefact of specimen preparation. High‐resolution images revealed lattice fringes in the matrix surrounding magnetite and greigite magnetosomes that were aligned with lattice fringes in the encapsulated magnetosomes. In all except one case, the lattice fringes had widths equal to or twice the width of the corresponding lattice fringes in the magnetosomes. The lattice fringes in the matrix were aligned with the {311}, {220}, {331}, {111} and {391} related lattice planes of magnetite and the {222} lattice plane of greigite. An unidentified material, possibly an iron hydroxide, was detected in two immature magnetosomes containing magnetite. The unidentified phase had a structure similar to that of the matrix as it contained {311}, {220} and {111} lattice fringes, which indicates that the matrix acts as a template for the spatially controlled biomineralization of the unidentified phase, which itself transforms into magnetite. The unidentified phase was thus called pre‐magnetite. The presence of the magnetosomal matrix explains all of the five properties of the biosignature of the magnetosomal chain proposed previously by Friedmann et al. and supports their claim that some of the magnetite particles in the carbonate globules in the Martian meteorite ALH84001 are biogenic. Two new morphologies of magnetite magnetosomes are also reported here (i.e. tooth‐shaped and hexa‐octahedral magnetosomes). Tooth‐shaped magnetite magnetosomes elongated in the [110] direction are reported, and are distinct from arrowhead‐shaped and bullet‐shaped magnetosomes. Elongation of magnetite magnetosomes in the [110] direction has not been reported previously. A Martian hexa‐octahedral magnetite particle was previously characterized by Thomas‐Keptra et al. and compared with truncated hexa‐octahedral magnetite magnetosomes. Hexa‐octahedral magnetite magnetosomes with the same morphology and similar sizes and axial ratios as those reported by Thomas‐Keptra et al. are characterized here. These observations support their claim that ALH84001 contains evidence for a past Martian biota.     

Quality control protocol for in vitro micro‐computed tomography

The aim of this work was to present and discuss a quality control protocol for in vitro micro‐computed tomography (microCT), based on the adaptation of the quality control protocols for medical computed tomography. The importance of establishing a quality control protocol is related to the opportunity to identify problems on time comparing the microCT images acquired in different time points, and in this way to verify the performance of the device. The proposed quality control protocol was applied for a long‐time monitoring period to verify the stability of the micro‐tomographic system over time. The protocol proposed in this study was applied to the histomorphometric characterization of bone tissue, but it can be used on a wide range of in vitro microCT applications. Noise and uniformity tests, taken and adapted to micro‐tomographic system by medical standard guidelines of quality control, were performed by the use of a water phantom. An accuracy test was designed and performed by the use of a morphometric calibrated phantom. All these tests were performed during a long‐time monitoring period to control the stability of the system. Specific control charts and monitoring parameters for each test were used to represent the monthly measures collected during 20 months and an out of control condition was defined. The reference values (baseline), calculated to control the stability of micro‐tomographic system over time, were calculated during acceptance/status test. During the period, no out of control conditions in noise, uniformity and accuracy tests were recorded. However, a changing condition was found in noise test, as showed by using statistical C (P < 0.01) and Kruskal–Wallis (P < 0.05) tests. In particular, a Wilcoxon rank sum test with Bonferroni correction (P < 0.0125) was applied in noise test to investigate which of the comparisons among first five acquisitions of year 2004 (group B.L.) and each group was significant (P < 0.0125). The noise showed a slight but significant increase over the years compared to baseline value; however, no out of control conditions were recorded. Nonetheless, a maintenance service to control the performance of mechanical components of microCT was required and performed.     

Comparison of the efficacies of two different fiber post‐removal systems: A micro‐computed tomography study

The aim of this in vitro study was to compare the efficacies of two different fiber post‐removal systems. Thirty extracted single‐rooted mandibular premolar teeth were used. After RelyX fiber posts were cemented, the teeth were divided into two groups with regard to the post removal techniques: ultrasonic vibration and D.T. Light‐Post removal kit. Residual material, tooth volume changes, working time and micro‐crack formation were assessed using micro‐computed tomography. All data were analyzed using Wilcoxon signed‐rank and Mann–Whitney U tests. There was significantly more tooth root volume change in the ultrasonic group than removal kit group (p < .05). Fiber post removal time for the ultrasonic group was significantly longer than the removal kit group (p < .01).     

Vascular imaging with contrast agent in hard and soft tissues using microcomputed‐tomography

Vascularization is essential for many tissues and is a main requisite for various tissue‐engineering strategies. Different techniques are used for highlighting vasculature, in vivo and ex vivo, in 2‐D or 3‐D including histological staining, immunohistochemistry, radiography, angiography, microscopy, computed tomography (CT) or micro‐CT, both stand‐alone and synchrotron system. Vascularization can be studied with or without a contrast agent. This paper presents the results obtained with the latest Skyscan micro‐CT (Skyscan 1272, Bruker, Belgium) following barium sulphate injection replacing the bloodstream in comparison with results obtained with a Skyscan In Vivo 1076. Different hard and soft tissues were perfused with contrast agent and were harvested. Samples were analysed using both forms of micro‐CT, and improved results were shown using this new micro‐CT. This study highlights the vasculature using micro‐CT methods. The results obtained with the Skyscan 1272 are clearly defined compared to results obtained with Skyscan 1076. In particular, this instrument highlights the high number of small vessels, which were not seen before at lower resolution. This new micro‐CT opens broader possibilities in detection and characterization of the 3‐D vascular tree to assess vascular tissue engineering strategies.     

Generating standardized image data for testing and calibrating quantification of volumes,surfaces, lengths,and object counts in fibrous and porous materials using X‐ray microtomography

Quantification of the structure and composition of biomaterials using micro‐CT requires image segmentation due to the low contrast and overlapping radioopacity of biological materials. The amount of bias introduced by segmentation procedures is generally unknown. We aim to develop software that generates three‐dimensional models of fibrous and porous structures with known volumes, surfaces, lengths, and object counts in fibrous materials and to provide a software tool that calibrates quantitative micro‐CT assessments. Virtual image stacks were generated using the newly developed software TeIGen, enabling the simulation of micro‐CT scans of unconnected tubes, connected tubes, and porosities. A realistic noise generator was incorporated. Forty image stacks were evaluated using micro‐CT, and the error between the true known and estimated data was quantified. Starting with geometric primitives, the error of the numerical estimation of surfaces and volumes was eliminated, thereby enabling the quantification of volumes and surfaces of colliding objects. Analysis of the sensitivity of the thresholding upon parameters of generated testing image sets revealed the effects of decreasing resolution and increasing noise on the accuracy of the micro‐CT quantification. The size of the error increased with decreasing resolution when the voxel size exceeded 1/10 of the typical object size, which simulated the effect of the smallest details that could still be reliably quantified. Open‐source software for calibrating quantitative micro‐CT assessments by producing and saving virtually generated image data sets with known morphometric data was made freely available to researchers involved in morphometry of three‐dimensional fibrillar and porous structures in micro‐CT scans.     

Three‐dimensional imaging of whole mouse models: comparing nondestructive X‐ray phase‐contrast micro‐CT with cryotome‐based planar epi‐illumination imaging

In this study, we compare two evolving techniques for obtaining high‐resolution 3D anatomical data of a mouse specimen. On the one hand, we investigate cryotome‐based planar epi‐illumination imaging (cryo‐imaging). On the other hand, we examine X‐ray phase‐contrast micro‐computed tomography (micro‐CT) using synchrotron radiation. Cryo‐imaging is a technique in which an electron multiplying charge coupled camera takes images of a cryo‐frozen specimen during the sectioning process. Subsequent image alignment and virtual stacking result in volumetric data. X‐ray phase‐contrast imaging is based on the minute refraction of X‐rays inside the specimen and features higher soft‐tissue contrast than conventional, attenuation‐based micro‐CT. To explore the potential of both techniques for studying whole mouse disease models, one mouse specimen was imaged using both techniques. Obtained data are compared visually and quantitatively, specifically with regard to the visibility of fine anatomical details. Internal structure of the mouse specimen is visible in great detail with both techniques and the study shows in particular that soft‐tissue contrast is strongly enhanced in the X‐ray phase images compared to the attenuation‐based images. This identifies phase‐contrast micro‐CT as a powerful tool for the study of small animal disease models.     

Presence of voids after warm vertical compaction and single‐cone obturation in band‐shaped isthmuses using micro‐computed tomography: A phantom study

The present micro‐computed tomography (micro‐CT) study compared the presence of voids in the band‐shaped isthmuses obturated by warm vertical compaction (WVC) and single‐cone (SC) techniques. Twenty mesial roots from mandibular first molar teeth showing a band‐shaped isthmus were selected and assigned into two groups based on their preoperative anatomical dimensions (n = 10), according to the filling technique: WVC or SC. Post‐filling micro‐CT scanning was performed. The percentage volume of root canal filling materials and voids were calculated and data were analyzed using the Mann–Whitney U test with a significance level of 5 and 95% confidence interval. Mean percentage volumes of filling materials and voids were 86.88 ± 8.53 and 13.11 ± 8.53 for the WVC group, 84.39 ± 8.30 and 15.60 ± 8.30 for the SC group, respectively, with no significant difference between them (p > .05). Neither WVC nor SC produced void‐free root canal fillings in the band‐shaped isthmuses and both techniques resulted in a similar quality of root canal filling.     

Spatial and temporal changes of subchondral bone proceed to articular cartilage degeneration in rats subjected to knee immobilization

This study was aimed to investigate the spatial and temporal changes of subchondral bone and its overlying articular cartilage in rats following knee immobilization. A total of 36 male Wistar rats (11–13 months old) were assigned randomly and evenly into 3 groups. For each group, knee joints in 6 rats were immobilized unilaterally for 1, 4, or 8 weeks, respectively, while the remaining rats were allowed free activity and served as external control groups. For each animal, femurs at both sides were dissected after sacrificed. The distal part of femur was examined by micro‐CT. Subsequently, femoral condyles were collected for further histological observation and analysis. For articular cartilage, significant changes were observed only at 4 and 8 weeks of immobilization. The thickness of articular cartilage and chondrocytes numbers decreased with time. However, significant changes in subchondral bone were defined by micro‐CT following immobilization in a time‐dependent manner. Immobilization led to a thinner and more porous subchondral bone plate, as well as a reduction in trabecular thickness and separation with a more rod‐like architecture. Changes in subchondral bone occurred earlier than in articular cartilage. More importantly, immobilization‐induced changes in subchondral bone may contribute, at least partially, to changes in its overlying articular cartilage. Microsc. Res. Tech. 79:209–218, 2016. © 2016 Wiley Periodicals, Inc.     

A novel scale‐down cell culture and imaging design for the mechanistic insight of cell colonisation within porous substrate

At the core of translational challenges in tissue engineering is the mechanistic understanding of the underpinning biological processes and the complex relationships among components at different levels, which is a challenging task due to the limitations of current tissue culture and assessment methodologies. Therefore, we proposed a novel scale‐down strategy to deconstruct complex biomatrices into elementary building blocks, which were resembled by thin modular substrate and then evaluated separately in miniaturised bioreactors using various conventional microscopes. In order to investigate cell colonisation within porous substrate in this proof‐of‐concept study, TEM specimen supporters (10–30 μm thick) with fine controlled open pores (100～600 μm) were selected as the modular porous substrate and suspended in 3D printed bioreactor systems. Noninvasive imaging of human dermal fibroblasts cultured on these free‐standing substrate using optical microscopes illustrated the complicated dynamic processes used by both individual and coordinated cells to bridge and segment porous structures. Further in situ analysis via SEM and TEM provided high‐quality micrographs of cell–cell and cell–scaffold interactions at microscale, depicted cytoskeletal structures in stretched and relaxed areas at nanoscale. Thus this novel scaled‐down design was able to improve our mechanistic understanding of tissue formation not only at single‐ and multiple‐cell levels, but also at micro‐ and nanoscales, which could be difficult to obtain using other methods.     

Ultrastructural characteristics of ovine bone marrow‐derived mesenchymal stromal cells cultured with a silicon stabilized tricalcium phosphate bioceramic

Bioceramics are being used in experimental bone engineering application in association with bone marrow derived mesenchymal stem cells (BM‐MSCs) as a new therapeutic tool, but their effects on the ultrastructure of BM‐MSCs are yet unknown. In this study we report the morphological features of ovine (o)BM‐MSCs cultured with Skelite, a resorbable bioceramic based on silicon stabilized tricalcium phosphate (SiTCP), able to promote the repair of induced bone defect in sheep model. oBM‐MSCs were isolated from the iliac crest, cultured until they reached near‐confluence and incubated with SiTCP. After 48 hr the monolayers were highly damaged and only few cells adhered to the plastic. Thus, SiTCP was removed, and after washing the cells were cultured until they became confluent. Then, they were trypsinizated and processed for transmission electron microscopy (TEM) and RT‐PCR analysis. RT‐PCR displayed that oBM‐MSCs express typical surface marker for MSCs. TEM revealed the presence of electron‐lucent cells and electron‐dense cells, both expressing the CD90 surface antigen. The prominent feature of electron‐lucent cells was the concentration of cytoplasmic organelles around the nucleus as well as large surface blebs containing glycogen or profiles of endoplasmic reticulum. The dark cells had a multilocular appearance by the presence of peripheral vacuoles. Some dark cells contained endocytic vesicles, lysosomes, and glycogen aggregates. oBM‐MSCs showed different types of specialized interconnections. The comparison with ultrastructural features of untreated oBM‐MSCs suggests the light and dark cells are two distinct cell types which were differently affected by SiTCP bioceramic. Skelite cultured ovine BM‐MSCs display electron‐dense and electron‐lucent cells which are differently affected by this bioceramic. This suggests that they could play a different role in bioceramic based therapy.     

仿生骨支架微观孔结构的构建与评价

在分析人体骨微观孔结构和影响支架性能因素的基础上,提出仿生骨支架微观孔结构的构建与评价方法。基于多约束背包问题模型的结构,以椭球体作为构建微观孔结构负模型的单元体,利用混合遗传算法求解微观孔结构的负模型;并将孔隙率和连通性作为约束条件,以保证仿生骨支架具有生物活性。通过不含微观孔的支架模型与负模型之间的布尔运算,构建含有微观孔结构的仿生骨支架模型。以支架的孔隙率、孔间的连通性、孔分布的均匀性、孔道的扭曲度和支架的比表面积作为评价指标,建立仿生骨支架微观孔结构的评价体系。基于支架微观孔结构的负模型,提出支架的孔隙率、连通性、均匀性、扭曲度和比表面积的计算方法,以实现对仿生骨支架微观孔结构的评价与优化。通过上述方法构建的仿生骨支架具有良好的生物活性、较好的力学性能以及均衡的降解速度。     

X-ray high-resolution vascular network imaging

This paper presents the first application of high‐resolution X‐ray synchrotron tomography to the imaging of large microvascular networks in biological tissue samples. This technique offers the opportunity of analysing the full three‐dimensional vascular network from the micrometre to the millimetre scale. This paper presents the specific sample preparation method and the X‐ray imaging procedure. Either barium or iron was injected as contrast agent in the vascular network. The impact of the composition and concentration of the injected solution on the X‐ray synchrotron tomography images has been studied. Two imaging modes, attenuation and phase contrast, are compared. Synchrotron high‐resolution computed tomography offers new prospects in the three‐dimensional imaging of in situ biological vascular networks.     

3D correlative morphological and elemental characterization of materials at the deep submicrometre scale

This paper shows how X‐ray computed nanotomography (CNT) can be correlated with focused ion beam time‐of‐flight secondary ion mass spectrometry (FIB‐TOF‐SIMS) tomography on the same sample to investigate both the morphological and elemental structure. This methodology is applicable to relatively large specimens with dimensions of several tens of microns whilst maintaining a high spatial resolution of the order of 100 nm. However, combining X‐ray CNT and FIB‐TOF‐SIMS tomography requires innovative sample preparation protocols to allow both experiments to be conducted on exactly the same sample without chemically or structurally modifying the sample between measurements. Moreover, dedicated algorithms have been developed for effective data fusion that is biased with nine degrees of freedom. This methodology has been tested using a porous and heterogeneous solid oxide fuel cell (SOFC) that has features varying in size by three orders of magnitude – from hundreds of nanometre large pores and grains to tens of micron wide functional layers.