Use Of micro-CT Research Articles

Interpreting the three-dimensional orientation of vascular canals and cross-sectional geometry of cortical bone in birds and bats.

Cortical bone porosity and specifically the orientation of vascular canals is an area of growing interest in biomedical research and comparative/paleontological anatomy. The potential to explain microstructural adaptation is of great interest. However, the determinants of the development of canal orientation remain unclear. Previous studies of birds have shown higher proportions of circumferential canals (called laminarity) in flight bones than in hindlimb bones, and interpreted this as a sign that circumferential canals are a feature for resistance to the torsional loading created by flight. We defined the laminarity index as the percentage of circumferential canal length out of the total canal length. In this study we examined the vascular canal network in the humerus and femur of a sample of 31 bird and 24 bat species using synchrotron micro‐computed tomography (micro‐CT) to look for a connection between canal orientation and functional loading. The use of micro‐CT provides a full three‐dimensional (3D) map of the vascular canal network and provides measurements of the 3D orientation of each canal in the whole cross‐section of the bone cortex. We measured several cross‐sectional geometric parameters and strength indices including principal and polar area moments of inertia, principal and polar section moduli, circularity, buckling ratio, and a weighted cortical thickness index. We found that bat cortices are relatively thicker and poorly vascularized, whereas those of birds are thinner and more highly vascularized, and that according to our cross‐sectional geometric parameters, bird bones have a greater resistance to torsional stress than the bats; in particular, the humerus in birds is more adapted to resist torsional stresses than the femur. Our results show that birds have a significantly (P = 0.031) higher laminarity index than bats, with birds having a mean laminarity index of 0.183 in the humerus and 0.232 in the femur, and bats having a mean laminarity index of 0.118 in the humerus and 0.119 in the femur. Counter to our expectation, the birds had a significantly higher laminarity index in the femur than in the humerus (P = 0.035). To evaluate whether this discrepancy was a consequence of methodology we conducted a comparison between our 3D method and an analogue to two‐dimensional (2D) histological measurements. This comparison revealed that 2D methods significantly underestimate (P < 0.001) the amount of longitudinal canals by an average of 20% and significantly overestimate (P < 0.001) the laminarity index by an average of 7.7%, systematically mis‐estimating indices of vascular canal orientations. In comparison with our 3D results, our approximated 2D measurement had the same results for comparisons between the birds and bats but found significant differences only in the longitudinal index between the humerus and the femur for both groups. The differences between our 3D and pseudo‐2D results indicate that differences between our findings and the literature may be partially based in methodology. Overall, our results do not support the hypothesis that the bones of flight are more laminar, suggesting a complex relation between functional loading and microstructural adaptation.

Standard method for microCT-based additive manufacturing quality control 3: Surface roughness

The use of microCT of 10?mm coupon samples produced by AM has the potential to provide useful information of mean density and detailed porosity information of the interior of the samples. In addition, the same scan data can be used to provide surface roughness analysis of the as-built surfaces of the same coupon samples. This can be used to compare process parameters or new materials. While surface roughness is traditionally done using tactile probes or with non-contact interferometric techniques, the complex surfaces in AM are sometimes difficult to access and may be very rough, with undercuts and may be difficult to accurately measure using traditional techniques which are meant for smoother surfaces. This standard workflow demonstrates on a coupon sample how to acquire surface roughness results, and compares the results from roughly the same area of the same sample with tactile probe results. The same principle can be applied to more complex parts, keeping in mind the resolution limit vs sample size of microCT.

Novel Application of Micro-Computerized Tomography for Morphologic Characterization of the Murine Penis

BackgroundThe murine penis model has enriched our understanding of anomalous penile development. The morphologic characterization of the murine penis using conventional serial sectioning methods is labor intensive and prone to errors. AimTo develop a novel application of micro-computerized tomography (micro-CT) with iodine staining for rapid, non-destructive morphologic study of murine penis structure. MethodsPenises were dissected from 10 adult wild-type mice and imaged using micro-CT with iodine staining. Images were acquired at 5-μm spatial resolution on a Bruker SkyScan 1272 micro-CT system. After images were acquired, the specimens were washed of any remaining iodine and embedded in paraffin for conventional histologic examination. Histologic and micro-CT measurements for all specimens were made by 2 independent observers. OutcomesMeasurements of penile structures were made on virtual micro-CT sections and histologic slides. ResultsThe Lin concordance correlation coefficient demonstrated almost perfect strength of agreement for interobserver variability for histologic section (0.9995, 95% CI = 0.9990–0.9997) and micro-CT section (0.9982, 95% CI = 0.9963–0.9991) measurements. Bland-Altman analysis for agreement between the 2 modalities of measurement demonstrated mean differences of −0.029, 0.022, and −0.068 mm for male urogenital mating protuberance, baculum, and penile glans length, respectively. There did not appear to be a bias for overestimation or underestimation of measured lengths and limits of agreement were narrow. Clinical TranslationThe enhanced ability offered by micro-CT to phenotype the murine penis has the potential to improve translational studies examining the molecular pathways contributing to anomalous penile development. Strengths and LimitationsThe present study describes the first reported use of micro-CT with iodine staining for imaging the murine penis. Producing repeated histologic sections of identical orientation was limited by inherent imperfections in mounting and tissue sectioning, but this was compensated for by using micro-CT reconstructions to identify matching virtual sections. ConclusionThis study demonstrates the successful use of micro-CT with iodine staining, which has the potential for submicron spatial resolution, as a non-destructive method of characterizing murine penile morphology.O'Neill M, Huang GO, Lamb DJ. Novel Application of Micro-Computerized Tomography for Morphologic Characterization of the Murine Penis. J Sex Med 2017;14:1533–1539.

Next-generation morphological character discovery and evaluation: an X-ray micro-CT enhanced revision of the ant genus Zasphinctus Wheeler (Hymenoptera, Formicidae, Dorylinae) in the Afrotropics.

New technologies for imaging and analysis of morphological characters offer opportunities to enhance revisionary taxonomy and better integrate it with the rest of biology. In this study, we revise the Afrotropical fauna of the ant genus Zasphinctus Wheeler, and use high-resolution X-ray microtomography (micro-CT) to analyse a number of morphological characters of taxonomic and biological interest. We recognise and describe three new species: Z. obamai sp. n., Z. sarowiwai sp. n., and Z. wilsoni sp. n. The species delimitations are based on the morphological examination of all physical specimens in combination with 3D scans and volume reconstructions. Based on this approach, we present a new taxonomic discrimination system for the regional fauna that consists of a combination of easily observable morphological characters visible at magnifications of around 80–100 ×, less observable characters that require higher magnifications, as well as characters made visible through virtual dissections that would otherwise require destructive treatment. Zasphinctus are rarely collected ants and the material available to us is comparatively scarce. Consequently, we explore the use of micro-CT as a non-invasive tool for the virtual examination, manipulation, and dissection of such rare material. Furthermore, we delineate the treated species by providing a diagnostic character matrix illustrated by numerous images and supplement that with additional evidence in the form of stacked montage images, 3D PDFs and 3D rotation videos of scans of major body parts and full body (in total we provide 16 stacked montage photographs, 116 images of 3D reconstructions, 15 3D rotation videos, and 13 3D PDFs). In addition to the comparative morphology analyses used for species delimitations, we also apply micro-CT data to examine certain traits, such as mouthparts, cuticle thickness, and thoracic and abdominal muscles in order to assess their taxonomic usefulness or gain insights into the natural history of the genus. The complete datasets comprising the raw micro-CT data, 3D PDFs, 3D rotation videos, still images of 3D models, and coloured montage photos have been made available online as cybertypes (Dryad, http://dx.doi.org/10.5061/dryad.4s3v1).

Increased Innate Lymphoid Cells in Periodontal Tissue of the Murine Model of Periodontitis: The Role of AMP-Activated Protein Kinase and Relevance for the Human Condition.

Innate lymphoid cells (ILCs) are master regulators of immune and inflammatory responses, but their own regulatory mechanisms and functional roles of their subtypes (i.e., ILC1s–ILC3s) remain largely unresolved. Interestingly, AMP-activated protein kinase (AMPK), influences inflammatory responses, but its role in modulation of ILCs is not known. Periodontitis is a prevalent disorder with impairment of immune and inflammatory responses contributing importantly to its pathogenesis; however, neither the role of ILCs nor AMPK has been explored in this condition. We tested the hypotheses that (a) periodontitis increases ILCs and expression of relevant cytokines thereby contributing to inflammation and (b) knockdown of AMPK worsens indices of periodontitis in association with further increases in subtypes of ILCs and cytokine expression. The studies utilized wild-type (WT) and AMPK knockout (KO) mice, subjected to ligature-induced periodontitis or sham operation, in association with the use of micro-CT for assessment of bone loss, immunogold electron microscopy to show presence of ILCs in periodontal tissues, flow cytometry for quantitative assessment of subtypes of ILCs and RT-polymerase chain reaction analyses to measure mRNA expression of several relevant cytokines. The results for the first time show (a) presence of each subtype of ILCs in periodontal tissues of sham control and periodontitis animals, (b) that periodontitis is associated with increased frequencies of ILC1s–ILC3s with the effect more marked for ILC2s and differential phenotypic marker expression for ILC3s, (c) that AMPK KO mice display exacerbation of indices of periodontitis in association with further increases in the frequency of subtypes of ILCs with persistence of ILC2s effect, and (d) that periodontitis increased mRNA for interleukin (IL)-33, but not IL-5 or IL-13, in WT mice but expression of these cytokines was markedly increased in AMPK KO mice with periodontitis. Subsequently, we showed that human periodontitis is associated with increases in each ILCs subtype with the effect more marked for ILC2s and that mRNA expressions for IL-33 and IL-5 are markedly greater for sites affected by periodontitis than healthy sites. Collectively, these novel observations indicate a pivotal role for ILCs in pathogenesis of periodontitis and that AMPK is a regulator of their phenotype expression in this condition.

MP08-20 RAPID PHENOTYPING OF GENITOURINARY ANOMALIES IN MICE USING MICRO-CT

You have accessJournal of UrologyImaging/Radiology: Uroradiology I1 Apr 2017MP08-20 RAPID PHENOTYPING OF GENITOURINARY ANOMALIES IN MICE USING MICRO-CT Gene Huang, Marisol O'Neill, Meade Haller, Carolina Jorgez, and D.J. Lamb Gene HuangGene Huang More articles by this author , Marisol O'NeillMarisol O'Neill More articles by this author , Meade HallerMeade Haller More articles by this author , Carolina JorgezCarolina Jorgez More articles by this author , and D.J. LambD.J. Lamb More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.307AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Mouse models serve as an excellent tool for studying human disease. Yet, the small size of the mouse presents technical challenges in characterizing organ defects. The use of micro-computed tomography (micro-CT) in biomedical research has historically been limited to studying osseous structures. However, development of iodine staining techniques has allowed for improved ex vivo study of soft tissue structures. Images acquired through micro-CT allow for limitless virtual sectioning (as thin as 2 µm), a distinct advantage over traditional tissue sectioning. In this study, we demonstrate the successful use of iodine staining and micro-CT to rapidly phenotype genitourinary (GU) anomalies in mice. METHODS Mice GU specimens were excised, fixed in formalin, and dehydrated in 70% ethanol. Iodine staining was performed by soaking the tissue in 0.1 N iodine (Fluka). The specimen was suspended in agar in preparation for imaging. Images were acquired using the SkyScan 1272 High-Resolution X-Ray Microtomograph (Bruker microCT, Kontich, Belgium). A 0.5 µm aluminum filter was utilized. Imaging parameters were 5 µm and 11 µm pixel size for penis and kidney specimens, respectively, and 2016 x 1344 resolution. Images were reconstructed using NRecon (Bruker microCT) and visualized using 3D Slicer v4 (slicer.org). RESULTS Both embryonic and adult mice GU specimens were imaged. Micro-CT scan time varied with specimen size and desired resolution, but was at longest 120 minutes. Normal and pathologic GU phenotypes were characterized on three-dimensional, reconstructed images. Embryonic GU systems were examined, including a number of hydronephrotic kidneys (top left). Normal, hydronephrotic, duplex (top right), and polycystic kidneys (bottom left) were identified in adult specimens. Adult penile specimens (bottom right) were reconstructed to allow for morphometric measurements. CONCLUSIONS We demonstrate successful generation of three-dimensional, high-resolution, contrast-enhanced images of GU organs in the murine model using micro-CT. The use of micro-CT possesses a vast potential in rapid phenotyping and study of GU anomalies in the murine model. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e99 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Gene Huang More articles by this author Marisol O'Neill More articles by this author Meade Haller More articles by this author Carolina Jorgez More articles by this author D.J. Lamb More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A novel method for segmenting and aligning the pre- and post-implantation scaffolds of resorbable calcium-phosphate bone substitutes.

Calcium-phosphate scaffolds are being increasingly used to repair critical bone defects. Methods for the accurate characterization of the repair process are still lacking. The present study introduced and validated a novel image-processing technique, using micro-computed tomography (mCT) datasets, to investigate material phases present in biopsies. Specifically, the new method combined mCT datasets from the scaffold before and after implantation to access the characteristic data of the ceramic for more accurate analysis of bone biopsies, and as such to better understand the interactions of the scaffold design and the bone repair process.

Advanced Non-Destructive Ocular Visualization Methods by Improved X-Ray Imaging Techniques.

Due to limited X-ray contrast, the use of micro-CT in histology is so far not as widespread as predicted. While specific staining procedures—mostly using iodine—address this shortcoming, long diffusion times restrict its use in the often time-constrained daily routine. Recently, a novel staining protocol has been proposed using a biochemical preconditioning step, which increases the permeability of the cells for the staining agent. This could enable the imaging of entire organs of small mammals at a yet unmatched image quality with reasonable preparation and scan times. We here propose an adaptation of this technique for virtual ophthalmology and histology by volumetrically assessing both human and porcine eyes. Hereby, we demonstrate that (contrast-enhanced) micro-CT can outperform conventional histology in the assessment of tumor entities, as well as functioning as a supplementary tool for surgeons in the positioning of intraocular implants in-vitro and as a general assessment tool for ophthalmologic specimens.

Quantifying damage in polycrystalline ice via X-Ray computed micro-tomography

The use of X-ray computed micro-tomography (micro-CT) is presented here as a useful tool for the analysis and quantification of damage in polycrystalline ice. Although known to be useful for characterizing damage in many other materials, the use of micro-CT has not yet been adapted to the non-trivial case of also characterizing damage in polycrystalline ice. Samples of polycrystalline ice were tested in uniaxial compression at six different strain rates, spanning four orders of magnitude, from 1 × 10−6 s−1 to 1 × 10−3 s−1, and two different testing temperatures of −10 °C and −20 °C. The extent of cracking from each test is characterized via micro-CT imaging and is quantified via a newly proposed variant of the crack density tensor, which accounts for any anisotropy in the mean crack orientation and is shown to be equivalent to the materials anisotropy tensor. To account for anisotropy in the distribution of cracks, an eigenanalysis is also performed. The results show that micro-CT can be a useful tool for both visualizing and quantifying damage in polycrystalline ice and that a 3-D analog of the traditional second-rank crack density tensor can be readily calculated via commercially available software.

Use of microcomputed tomography for the evaluation of canal filling quality depending on the part of root canal

Introduction. High-resolution microcomputed tomography (microCT) is an emerging technology with several applications to endodontics. Aim of the study: To analyse in detail root canal fillings in the apical third, in the middle and coronal thirds in in vitro conditions with the use of microCT. Material and methods. Eighty single roots were prepared with the “step-back” technique or with a Pro File system using the “crown-down” technique. Each main group was divided into two subgroups and obturated with either cold lateral (CL) condensation or thermoplastic (Th) compaction with System B and Obtura II. The distribution of voids (number and volume) was assessed by means of microCT. Results. In the apical third of the root canal, in total over three times more external voids (e-voids) (598) with a greater volume than internal voids (i-voids) (167) were found. In the middle third the numbers of i-voids (664) and e-voids (651) were similar. The mean volume of i-voids was higher among root canals filled using CL condensation as compared to Th compaction (p=0.001). The greatest number of i-voids (3872) and e-voids (1888) were found in the coronal third. The mean volume of i-voids was higher among root canals filled using CL condensation as compared to those filled by means of Th compaction (p=0.001). Conclusions. Irrespective of the obturation methods, the most hermetically filled part of the root canal was the apical third while the coronal third was the least hermetically filled part. E-voids with a greater volume predominated in the apical part, while numerous small i-voids were detected closer to the crown.

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

The flow inside a purpose built enlarged single-orifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and high-speed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can be a reliable tool for cavitation in nozzle orifices operating under nominal steady-state conditions.

Prevalence and morphometric analysis of three-rooted mandibular first molars in a Brazilian subpopulation.

ABSTRACTThe knowledge of the internal anatomy of three-rooted mandibular molars may help clinicians to diagnose and plan the root canal treatment in order to provide adequate therapy when this variation is present.Objectives:To determine the prevalence of three-rooted mandibular molars in a Brazilian population using cone beam computed tomography (CBCT) and to analyze the anatomy of mandibular first molars with three roots through micro-CT.Material and Methods:CBCT images of 116 patients were reviewed to determine the prevalence of three-rooted first mandibular molars in a Brazilian subpopulation. Furthermore, with the use of micro-CT, 55 extracted three-rooted mandibular first molars were scanned and reconstructed to assess root length, distance between canal orifices, apical diameter, Vertucci's classification, presence of apical delta, number of foramina and furcations, lateral and accessory canals. The distance between the orifice on the pulp chamber floor and the beginning of the curvature and the angle of canal curvature were analyzed in the distolingual root. Data were compared using the Kruskal-Wallis test (α=0.05).Results:The prevalence of three-rooted mandibular first molars was of 2.58%. Mesial roots showed complex distribution of the root canal system in comparison to the distal roots. The median of major diameters of mesiobuccal, mesiolingual and single mesial canals were: 0.34, 0.41 and 0.60 mm, respectively. The higher values of major diameters were found in the distobuccal canals (0.56 mm) and the lower diameters in the distolingual canals (0.29 mm). The lowest orifice distance was found between the mesial canals (MB-ML) and the highest distance between the distal root canals (DB-DL). Almost all distal roots had one root canal and one apical foramen with few accessory canals.Conclusions:Distolingual root generally has short length, severe curvature and a single root canal with low apical diameter.

Textures in spinel peridotite mantle xenoliths using micro-CT scanning: Examples from Canary Islands and France

Spinel pyroxene-clusters, which are intergrowths of spinel, orthopyroxene and clinopyroxene in mantle xenoliths, have been investigated through the use of micro-CT (μ-CT) in this study. Samples have been studied from two different tectonic settings: (1) the northern Massif Central, France, an uplifted and rifted plateau on continental lithosphere and (2) Lanzarote in the Canary Islands, an intraplate volcanic island on old oceanic lithosphere. μ-CT analysis of samples from both locations has revealed a range of spinel textures from small <2mm microcrystals which can be either spatially concentrated or distributed more evenly throughout the rock with a lineation, to large 4–12mm individual clusters with ellipsoidal complex vermicular textures in random orientation. Microprobe analyses of pyroxenes inside and outside the clusters show broadly similar compositions. Spinel–pyroxene clusters are the result of a transition of shallow lithospheric mantle from the garnet stability field to the spinel stability field. Both the northern Massif Central and Lanzarote are regions that have experienced significant lithospheric thinning. This process provides a mechanism where the sub-solidus reaction of olivine+garnet=orthopyroxene+clinopyroxene+spinel is satisfied by providing a pathway from garnet peridotite to spinel peridotite. We predict that such textures would only occur in the mantle beneath regions that show evidence of thinning of the lithospheric mantle. Metasomatic reactions are seen around spinel–pyroxene clusters in some Lanzarote xenoliths, so metasomatism post-dated cluster formation.

High-contrast X-ray micro-radiography and micro-CT of ex-vivo soft tissue murine organs utilizing ethanol fixation and large area photon-counting detector.

Using dedicated contrast agents high-quality X-ray imaging of soft tissue structures with isotropic micrometre resolution has become feasible. This technique is frequently titled as virtual histology as it allows production of slices of tissue without destroying the sample. The use of contrast agents is, however, often an irreversible time-consuming procedure and despite the non-destructive principle of X-ray imaging, the sample is usually no longer usable for other research methods. In this work we present the application of recently developed large-area photon counting detector for high resolution X-ray micro-radiography and micro-tomography of whole ex-vivo ethanol-preserved mouse organs. The photon counting detectors provide dark-current-free quantum-counting operation enabling acquisition of data with virtually unlimited contrast-to-noise ratio (CNR). Thanks to the very high CNR even ethanol-only preserved soft-tissue samples without addition of any contrast agent can be visualized in great detail. As ethanol preservation is one of the standard steps of tissue fixation for histology, the presented method can open a way for widespread use of micro-CT with all its advantages for routine 3D non-destructive soft-tissue visualisation.

A novel method for contact analysis of rubber and various surfaces using micro-computerized-tomography

The experimental analysis of the contact state in a tribosystem is of great importance in the study of contact mechanics. In order to make a realistic analysis on the micro scale, it is desirable to keep the tribosystem unperturbed, i.e., without any surface treatment or incorporation of a third body to facilitate the analysis. This study presents the use of a novel technique, micro-computerized tomography (micro-CT), in the investigation of contact between rubber compounds and various counter-surfaces. The goal of this study was to further advance the use of micro-CT in contact mechanics. Specific image analysis techniques were developed in order to process micro-CT images of contact pairs formed by rubber compounds of different hardness levels against counter-surfaces with varying surface roughness and mechanical properties. The micro-CT method has been shown to allow the direct visualization and precise quantification of the real area of contact without altering the original characteristics of the contact pair.

Use of micro-computed tomography for the assessment of periapical lesions in small rodents: a systematic review.

This systematic review aimed to evaluate the literature on the acquisition-, reconstruction- and analysis parameters of micro-computed tomography (micro-CT) for the assessment of periapical lesions in rats and mice, and to illustrate the effect of variation in these parameters. The PubMed database was searched from 2000 to January 2015 (English-language publications) for reports on the use of micro-CT to evaluate periapical lesions in rats and mice. QUADAS criteria were used to rate the quality of the studies. To illustrate the effect of variations in acquisition-, reconstruction-, and analysis parameters on images of periapical lesions, micro-CT examination of two hemi-mandibles of mice, with periapical lesions around the first molar was undertaken. Twenty-one studies were identified, which analysed periapical lesions in rats or mice using micro-CT. According to the QUADAS, no study was classified as high-, seven were classified as moderate-, and 14 as low quality. The effect of variation in parameters was that voxel size may interfere with image sharpness, reconstruction may interfere with image sharpness and contrast, and inadequate plane orientation may alter the size of the periapical lesion. Nonpersonalized ROIs resulted in areas that were not part of the periapical lesion. Changing the limits of the threshold for bone-tissue visualization increased lesion size. There is no defined protocol for acquiring and analysing micro-CT images of periapical lesions in rats and mice. Furthermore, acquisition-, reconstruction- and analysis parameters are not adequately explained, which may compromise the scientific impact of the studies.

Systematic revision of the Malagasy chameleons Calumma boettgeri and C. linotum (Squamata: Chamaeleonidae).

We revise the taxonomic status of two species of Madagascan chameleons in light of a recent molecular phylogenetic study on the Calumma nasutum group. The investigation of morphological and osteological characters led to a clear delineation between two species within the C. boettgeri complex, C. boettgeri and C. linotum. Calumma linotum has been considered either a synonym of C. boettgeri or a dubious, poorly defined taxon. So far it has only been known from the male holotype with the imprecise locality 'Madagascar'. Based on pholidosis, morphological measurements and characters of the skull that were analyzed using micro-X-ray computed tomography (micro-CT) scans, we ascribe the population of chameleons from Montagne d'Ambre, formerly assigned to C. boettgeri, to C. linotum. Calumma linotum differs from C. boettgeri in the larger size of tubercle scales on the extremities and rostral appendage, the larger diameter of the extremities relative to the body size, the presence of a parietal crest as well as the form of the nasal bones and the anterior tip of the frontal. The life colouration of the males is also characteristic, with a blue rostral appendage and greenish turquoise extremities. The body and rostral appendage of C. boettgeri in contrast are inconspicuously yellowish brown coloured. All confirmed distribution records of C. boettgeri are confined to the biogeographic Sambirano region whereas C. linotum is only known from Montagne d'Ambre and a locality at the base of the Tsaratanana massif. Additional literature records of C. boettgeri and C. linotum from northeastern Madagascar are in need of confirmation. We also confirm the synonymy of Chamaeleo macrorhinus (described from a female holotype with an unknown locality) with Calumma boettgeri. The use of micro-CT exposed further characteristics for species delimitation in an integrative taxonomic approach. In addition to the skull, we also micro-CT scanned the hemipenes of C. boettgeri and C. linotum, using an iodine-based tissue stain, and provide 3D PDF models of these organs. This method enables detailed illustration and the detection of variation in particular characters, and might be an important tool in further taxonomic studies on the C. nasutum group and other squamate reptiles.

Characteristics of bone fractures and usefulness of micro-computed tomography for fracture detection in rabbits: 210 cases (2007-2013).

To characterize bone fractures and the usefulness of micro-CT for imaging fractures in pet rabbits. Retrospective case series. 210 client-owned rabbits with bone fractures. Medical records of rabbits evaluated for bone fractures from 2007 through 2013 were examined. Information was collected on signalment and nature of fractures, and radiographic and micro-CT images of fractures were reviewed. Almost half (n = 95 [47.7%]) of fractures were in rabbits < 3 years old. Accidental fall was the most common cause. Vertebral fracture was the most common type of fracture with a nonneoplastic cause (n = 46 [23.2%]) and was most common in the L4-L7 region. The tibia was the most common site for limb fracture among all fractures with a nonneoplastic cause (45 [22.7%]). Twelve (5.7%) fractures had a neoplastic cause, and 7 of these were associated with metastatic uterine adenocarcinoma. Females were significantly more likely to have a fracture caused by neoplasia than were males. Compared with radiography, micro-CT provided more detailed fracture information, particularly for complicated fractures or structures (eg, skull, pelvic, vertebral, and comminuted limb fractures). Findings were useful for understanding the nature of fractures in pet rabbits and supported the use of micro-CT versus radiography for fracture detection and evaluation.

The use of micro-CT with image segmentation to quantify leakage in dental restorations

ObjectiveTo develop a method for quantifying leakage in composite resin restorations after curing, using non-destructive X-ray micro-computed tomography (micro-CT) and image segmentation. MethodsClass-I cavity preparations were made in 20 human third molars, which were divided into 2 groups. Group I was restored with Z100 and Group II with Filtek LS. Micro-CT scans were taken for both groups before and after they were submerged in silver nitrate solution (AgNO3 50%) to reveal any interfacial gap and leakage at the tooth restoration interface. Image segmentation was carried out by first performing image correlation to align the before- and after-treatment images and then by image subtraction to isolate the silver nitrate penetrant for precise volume calculation. Two-tailed Student's t-test was used to analyze the results, with the level of significance set at p<0.05. ResultsAll samples from Group I showed silver nitrate penetration with a mean volume of 1.3±0.7mm3. In Group II, only 2 out of the 10 restorations displayed infiltration along the interface, giving a mean volume of 0.3±0.3mm3. The difference between the two groups was statistically significant (p<0.05). The infiltration showed non-uniform patterns within the interface. SignificanceWe have developed a method to quantify the volume of leakage using non-destructive micro-CT, silver nitrate infiltration and image segmentation. Our results confirmed that substantial leakage could occur in composite restorations that have imperfections in the adhesive layer or interfacial debonding through polymerization shrinkage. For the restorative systems investigated in this study, this occurred mostly at the interface between the adhesive system and the tooth structure.

Micro-CT and histological analysis of Ti6Al7Nb custom made implants with hydroxyapatite and SiO2-TiO2 coatings in a rabbit model.

Background and aimBone defect reconstruction in the maxillofacial area comes as a necessity after traumatic, oncological or congenital pathology. Custom made implant manufacturing, such as selective laser melting (SLM), is very helpful when bone reconstruction is needed. In the present study we assessed the osseointegration of custom made implants made of Ti6Al7Nb with two different coatings: SiO2-TiO2 and hydroxyapatite, by comparing the bone mineral density (BMD) measured on micro-CT and the histological mineralized bone surrounding the implants.MethodsCustom made – cylindrical type – implants were produced by selective laser melting, coated with SiO2-TiO2 and hydroxyapatite and implanted in the rabbit femur. The animals (divided into 3 groups) were sacrificed at 1, 3 and 6 months and the implants were removed together with the surrounding bone. Bone mineral density and histological examination of the bone-implant surface was performed for each group.ResultsBMD and histological examination of the samples determined the quantity of mineralized bone at the implant site, showing a good percentage of mineralized bone for the coated implants at 1, 3 and 6 months. The measurements for the implants without coating showed a significant lower quantity of mineralized bone at 3 months compared with the implants with coating, and a good quantity of mineralized bone at 6 months, showing a process of demineralization followed by remineralization in the last month. The measurements of BMD showed similar results with the histological examination.ConclusionsThe use of micro-CT and the measurement of BMD are a reliable, minimally invasive and a quick method of osseointegration assessment.