micro-CT Data Research Articles

Predicting Trabecular Bone Stiffness from Clinical Cone-Beam CT and HR-pQCT Data; an In Vitro Study Using Finite Element Analysis.

Stiffness and shear moduli of human trabecular bone may be analyzed in vivo by finite element (FE) analysis from image data obtained by clinical imaging equipment such as high resolution peripheral quantitative computed tomography (HR-pQCT). In clinical practice today, this is done in the peripheral skeleton like the wrist and heel. In this cadaveric bone study, fourteen bone specimens from the wrist were imaged by two dental cone beam computed tomography (CBCT) devices and one HR-pQCT device as well as by dual energy X-ray absorptiometry (DXA). Histomorphometric measurements from micro-CT data were used as gold standard. The image processing was done with an in-house developed code based on the automated region growing (ARG) algorithm. Evaluation of how well stiffness (Young’s modulus E3) and minimum shear modulus from the 12, 13, or 23 could be predicted from the CBCT and HR-pQCT imaging data was studied and compared to FE analysis from the micro-CT imaging data. Strong correlations were found between the clinical machines and micro-CT regarding trabecular bone structure parameters, such as bone volume over total volume, trabecular thickness, trabecular number and trabecular nodes (varying from 0.79 to 0.96). The two CBCT devices as well as the HR-pQCT showed the ability to predict stiffness and shear, with adjusted R2-values between 0.78 and 0.92, based on data derived through our in-house developed code based on the ARG algorithm. These findings indicate that clinically used CBCT may be a feasible method for clinical studies of bone structure and mechanical properties in future osteoporosis research.

Fast and long acting neoflavonoids dalbergin isolated from Dalbergia sissoo heartwood is osteoprotective in ovariectomized model of osteoporosis: Osteoprotective effect of Dalbergin.

This study aims to evaluate the skeletal effects of dalbergin (DBN), isolated from Dalbergia sissoo heartwood, in ovariectomized (OVx) BALB/c mice, a postmenopausal osteoporosis model of bone loss. Adult BALB/c mice were used and randomly assigned in to six groups with 6 animals (n=6) in each group: sham (surgery operated without ovariectomy) with vehicle, ovariectomy with vehicle, ovariectomy (OVx) with estradiol (E2 5.0μgkg-1day-1), or ovariectomy with dalbergin at three different doses of DBN (1.0, 5.0 and10mgkg-1day-1). Daily oral administration of the vehicle, estradiol, or DBN was started 8 weeks post-surgery and continued for 8 weeks. At the end of experiment, mice were sacrificed and assessed for trabecular bone structure of tibia, lumbar vertebra (L5) and alterations in biochemical and uterine parameters, pharmacokinetic profile and gene expression were monitored for each group. Treatment with DBN prevented trabecular bone loss in cancellous bone in the tibial metaphysis and lumbar vertebra region of the ovariectomized mice. Micro-CT data showed that mice treated with DBN at 1.0mgkg-1day-1 exhibited improved bone micro-architecture that was sustained with decreased expression of bone resorption markers like TRAP and RANK and caused an increase in osteogenic markers like RUNX2, BMP2 and OPG/RANKL ratio compared with OVx+vehicle treated mice. Moreover, DBN treatment induced no uterine estrogenicity and significantly lowered the osteocalcin amount in serum when compared with OVx+V group. DBN reached its maximum concentration (Cmax) 238.49±21.37ngml-1 in serum as early as 1h of administration. Overall, DBN (1.0mgkg-1day-1) treatment exhibited similar bone conserving effect against bone-loss as estradiol treatment. Daily oral administration of DBN for 8 weeks showed significant anabolic effects on bone micro-architectural parameters along with down regulation of bone resorptive markers without compromising safety at uterine level. Therefore, our study provides basis for DBN as a therapeutic candidate against postmenopausal osteoporosis.

Computer simulation of lumbar flexion shows shear of the facet capsular ligament

Background ContextThe lumbar facet capsular ligament (FCL) is a posterior spinal ligament with a complex structure and kinematic profile. The FCL has a curved geometry, multiple attachment sites, and preferentially aligned collagen fiber bundles on the posterior surface that are innervated with mechanoreceptive nerve endings. Spinal flexion induces three-dimensional (3D) deformations, requiring the FCL to maintain significant tensile and shear loads. Previous works aimed to study 3D facet joint kinematics during flexion, but to our knowledge none have reported localized FCL surface deformations likely created by this complex structure. PurposeThe purpose of this study was to elucidate local deformations of both the posterior and anterior surfaces of the lumbar FCL to understand the distribution and magnitude of in-plane and through-plane deformations, including the prevalence of shear. Study Design/SettingThe FCL anterior and posterior surface deformations were quantified through creation of a finite element model simulating facet joint flexion using a realistic geometry, physiological kinematics, and fitted constitutive material. MethodsGeometry was obtained from the micro-CT data of a healthy L3–L4 facet joint capsule (n=1); kinematics were extracted from sagittal plane fluoroscopic data of healthy volunteers (n=10) performing flexion; and average material properties were determined from planar biaxial extension tests of L4–L5 FCLs (n=6). All analyses were performed with the non-linear finite element solver, FEBio. A grid of equally spaced 3×3 nodes on the posterior surface identified regional differences within the strain fields and was used to create comparisons against previously published experimental data. This study was funded by the National Institutes of Health and the authors have no disclosures. ResultsInhomogeneous in-plane and through-plane shear deformations were prominent through the middle body of the FCL on both surfaces. Anterior surface deformations were more pronounced because of the small width of the joint space, whereas posterior surface deformations were more diffuse because the larger area increased deformability. We speculate these areas of large deformation may provide this proprioceptive system with an excellent measure of spinal motion. ConclusionsWe found that in-plane and through-plane shear deformations are widely present in finite element simulations of a lumbar FCL during flexion. Importantly, we conclude that future studies of the FCL must consider the effects of both shear and tensile deformations.

Numeric simulation of occlusal interferences in molars restored with ultrathin occlusal veneers

Statement of problemSelecting material for a minimally invasive occlusal veneer reconstruction concept requires an understanding of how stresses are distributed during functional and parafunctional forces. PurposeThe purpose of this in vitro study was to investigate stress distribution in a maxillary molar restored with ultrathin occlusal veneers and subjected by an antagonistic mandibular molar to clenching and working and nonworking movements. Material and MethodsA maxillary first molar was modeled from microcomputed tomography (micro-CT) data, using medical image processing software, stereolithography editing/optimizing software, and finite element software. Simulated ultrathin occlusal veneer materials were used. The mandibular molar antagonist was a solid nondeformable geometric entity. Loads simulated clenching, working, and nonworking movements with loading of 500 N. The values of the maximum principal stress were recorded. ResultsIn the clenching load situation, maximum tensile stresses were located at the occlusal veneer (52 MPa for composite resin versus 47 MPa for ceramic). In the working movement, significant additional tensile stresses were found on the palatal root (87 MPa for composite resin and 85 MPa for ceramic). In the nonworking movement, tensile stress on the ultrathin occlusal veneer increased to 118 MPa for composite resin and 143 MPa for ceramic veneers. Tensile stress peaks shifted to the mesiobuccal root (75 MPa for composite resin and 74 MPa for ceramic). ConclusionsThe topography of stresses generated by the various occlusal interferences were clearly identified. Significant tensile stress concentrations were found within the restoration’s occlusal topography and root, with the nonworking interference being the most harmful and also the most revealing of the difference between the composite resin and ceramic ultrathin occlusal veneers.

In vivo degradation of magnesium alloys and poly (lactic-co-glycolic acid) and degradation evaluation of magnesium alloys using micro-ct

?To explore the degradation of AZ31 magnesium alloy and poly (lactic-co-glycolic acid) (PLGA) in the femoral condyle, and then evaluate the laws of degradation of AZ31 magnesium alloy by Micro-CT images and data. ?Forty 3-month-old male New Zealand white rabbits (weighing, 2.5 kg) were randomly divided into 4 groups, 10 rabbits each group. Forty micro-arc-oxidized AZ31 magnesium alloy pins and 40 PLGA pins were implanted into the right and left femoral condyle, respectively. Micro-CT images and data analysis were used to evaluate the degradation at 4, 8, 12, and 16 weeks after operation (n=10). Degradation was evaluated by weight difference between pre-and post-implantation. The inflammatory response was observed around the implants by HE staining. The weight loss of magnesium alloy and Micro-CT results were compared. ?The Micro-CT images showed that PLGA pins had gray low signal, which was similar to the soft tissue around. At 4 weeks after operation, no signs of degradation were observed, and there were little corrosion pitting on the magnesium alloy. At 8 weeks, corrosion pitting gradually expanded, the boundary between the longitudinal axis and the cross section became blurred; at 16 weeks, corrosion pitting became bigger, and the boundary was discontinuous. Micro-CT quantitative analysis showed that the volume fraction of magnesium pins decreased slowly at 4 and 8 weeks; it was significantly lower at 12 and 16 weeks than 4 and 8 weeks (P<0.05). The magnesium cylinder mineral density continuously decreased during the study period, it had a rapidly speed from 12 to 16 weeks (P<0.05). However, the magnesium CT image density showed a slight change (P>0.05). The surface-to-volume ratio of the pins constantly increased, and the ratio was significantly larger at 12 and 16 weeks than 4 and 8 weeks, and at 16 weeks than 12 weeks (P<0.05). There was more and more corrosion pitting on the surface with time, which resulted in a decrease in the radius that mean trabecular thickness gradually decreased, showing significant difference between different time points after 8 weeks (P<0.05). The weight loss detection showed that the degradation of magnesium pin and PLGA gradually increased with time (P<0.05), and the degradation rate of magnesium pin was significantly lower than that of PLGA at 8-12 weeks (P<0.05), but the degradation rate of magnesium pin was higher than that of PLGA at 16 weeks. At each time point, the weight loss of magnesium alloy was similar to that by Micro-CT, but mass fraction was lower than volume fraction and had significant differences at 8, 12, and 16 weeks (P<0.05). HE staining revealed that slight inflammatory response was observed around the magnesium pins at 4 weeks, and inflammatory reaction gradually reduced with time and disappeared at 16 weeks, but no inflammatory reaction was seen around PLGA. ?Micro-CT has the advantages of non-trauma, in vivo detection, quantitative analysis, and precise data in evaluating the degradation of AZ31 magnesium alloy. Regarding the degradation of the magnesium alloy and PLGA in vivo, the degradation rate is slow in the early stage, and then increases with time. The degradation of PLGA is faster and earlier but it is then overtaken by AZ31 magnesium alloy at 16 weeks. During the degradation, the density of the magnesium has almost no change. The biomaterials can not firmly attach to the surrounding tissues due to inadequate holding forces.

Middle paleolithic human deciduous incisor from Grotta del Cavallo, Italy

In this contribution, we present a morphological description and comparative morphometric analysis of Cavallo D, a human tooth unearthed from the Mousterian FIII sublayer of Grotta del Cavallo (Apulia, Italy). We used microCT data to provide a detailed morphological description and morphometric analysis of the Cavallo D human tooth based on traditional diameter measurements and 3D enamel thickness. Moreover, new AMS radiocarbon dating of charcoals from layers FII was carried out. Morphological features observed in Cavallo D align the tooth to Neandertals. Similarly, the large size of the tooth (e.g., BL diameter) and the relatively thinner enamel thickness are typical Neandertal traits. 14 C datings of layer FII attribute the tooth to a time range of 45,600-42,900 cal BP (at 68% level of probability). Up to now, the Rdi1 Cavallo D represents the most recent Neandertal human remain in southern Italy related to a radiocarbon dated stratigraphy. Moreover, since deciduous teeth have been less investigated than the permanent ones, this contribution brings new data to increase our knowledge on the variability of the Neandertal deciduous dentition.

An Injured Psittacosaurus (Dinosauria: Ceratopsia) From the Yixian Formation (Liaoning, China): Implications for Psittacosaurus Biology.

We describe a Psittacosaurus specimen from the Lujiatun beds of the Yixian Formation in Liaoning, China with an abnormality on its left fibula. Although a large number of Psittacosaurus specimens are known, only a single example of a pathologic Psittacosaurus has been previously noted. The specific pathology in the current specimen is believed to be a healed fibular fracture as assessed through a combination of gross morphology, microcomputed tomography (microCT), and histology data. The fracture can be identified using microCT, but the degree of remodeling and the stage of fracture repair are best determined histologically. The fracture callus is made up of radially oriented spokes of woven bone in a cartilage matrix and the original cortical bone prior to the fracture has been largely eroded. A transverse histologic section taken at the level of the fracture shows the displacement of the proximal and distal parts of the fibula. The Psittacosaurus appears to have survived the break considering the deposition of circumferential non-pathologic bone at the periosteal surface outside of the callus. The combination of gross morphological description, microCT data, and histologic data allowed for a full diagnosis of the abnormality. While some previous authors have preferred gross morphological description above other methods for assessing paleopathologies, it is evident based on this specimen that an amalgam of techniques provides greater clarity to paleopathology diagnoses. Although this Psittacosaurus lived in an environment with many predators, it was able to survive with a fracture on its hindlimb, which undoubtedly would have impacted its locomotion. Anat Rec, 299:897-906, 2016. © 2016 Wiley Periodicals, Inc.

Influence of Hygrothermal Aging on Poisson’s Ratio of Thin Injection-Molded Short Glass Fiber-Reinforced PA6

The hygrothermal aging of short glass fiber-reinforced polyamide 6 materials (PA6 GF) represents a major problem, especially in thin-walled components, such as in the automotive sector. In this study, therefore, the thickness and the glass fiber content of PA6 GF materials were varied and the materials were exposed to hygrothermal aging. The temperature and relative humidity were selected in the range from −40 °C up to 85 °C, and from 10% up to 85% relative humidity (RH). In the dry-as-molded state, the determined Poisson’s ratio of the PA6 GF materials was correlated with the fiber orientation based on computer tomography (MicroCT) data and shows a linear dependence with respect to the fiber orientation along and transverse to the flow direction of the injection molding process. With hygrothermal aging, the value of Poisson’s ratio increases in the flow direction in the same way as it decreases perpendicular to the flow direction due to water absorption.

Anatomical and radiographic study of the mandibular retromolar canal

Background/purposeAs the demand for surgical procedure in the retromolar area of the mandible has been increasing, the identification of the retromolar foramen (RMF) and canal involving the retromolar triangle (RMT) has become an issue of clinical concern. We examined the shape of the RMT, incidence of the RMF, and intraosseous trajectory of the retromolar canal (RMC). Materials and methodsA total of 118 sides of dry mandibles, 22 sides of mandibles of 13 cadavers, and cone-beam computed tomography (CT) images of 100 patients were examined. Micro-CT data of 13 cadavers were reconstructed using imaging analysis software for the presence of an RMC. RMCs were classified into three types according to the courses. The width and location of the RMCs were evaluated. ResultsThe shape of the RMT was classified into three categories, with the most common type being the triangular type (81.4%). Forty-seven retromolar foramina (33.6%) were observed in 140 sides of mandibles. The horizontal distances from the RMF to the second and third molars were 12.1±3.3 mm and 5.8±3.6 mm (mean±standard deviation), respectively, and the distance from the mandibular foramen to the arising point of the RMC and the vertical distance from the RMF to the mandibular canal were 21.5±11.2 mm and 15.3±4.6 mm, respectively. ConclusionThis study used various methods to obtain precise anatomical data on the RMT, foramen, and canal in Koreans. The reported findings may be helpful for the clinical management of patients.

Coupling multiscale X-ray physics and micromechanics for bone tissue composition and elasticity determination from micro-CT data, by example of femora from OVX and sham rats

ABSTRACTDue to its high resolution, micro-CT (Computed Tomograph) scanning is the key to assess bone quality of sham and OVX (ovariectomized) rats. Combination of basic X-ray physics, such as the energy- and chemistry-dependence of attenuation coefficients, with results from ashing tests on rat bones, delivers mineral, organic, and water volume fractions within the voxels. Additional use of a microelastic model for bone provides voxel-specific elastic properties. The new method delivers realistic bone mass densities, and reveals that OVX protocols may indeed induce some bone mass loss, while the average composition of the bone tissue remains largely unaltered.

Effect of Epigallocatechin-3-Gallate on the alveolar bone remodeling and arthritis in collagen-induced arthritis model in mice

The aim of this study was to evaluate the effect of Epigallocatechin-3-Gallate (EGCG) on the alveolar bone metabolism in a collagen-induced arthritis (CIA) model in mice to enhance the understanding of rheumatoid arthritis (RA)-associated alveolar bone loss. Following the induction of CIA in animals (mice, n=16), mandibles were retrieved for micro-computed tomography (micro-CT) and isolation of alveolar bone cells (ABCs). In vitro osteogenic potentials of ABCs were evaluated and the mRNA expression of downstream effector genes was assessed. CIA was successfully induced in all animals, and micro-CT data showed that alveolar bone loss was significantly increased in the CIA group while the treatment of EGCG prevented the alveolar bone resorption. Osteogenesis by ABCs was significantly increased in the CIA+EGCG group in vitro. The analysis of mRNA expressions showed that osteoclastogenesis-associated genes were increased in CIA group while bone protecting genes were upregulated in EGCG treated group. The results demonstrate that EGCG downregulated the alveolar bone resorption in a CIA model in mice, and upregulation of bone protecting genes appear to be involved. Further studies are warranted.

Contrast-Enhanced X-Ray Micro-Computed Tomography as a Versatile Method for Anatomical Studies of Adult Zebrafish.

One attractive quality of zebrafish as a model organism for biological research is that transparency at early developmental stages allows the optical imaging of cellular and molecular events. However, this advantage cannot be applied to adult zebrafish. In this study, we explored the use of contrast-enhanced X-ray micro-computed tomography (microCT) on adult zebrafish in which the organism was stained with iodine, a simple and economical contrasting agent, after fixation. Tomographic reconstruction of the microCT data allowed the three-dimensional (3D) volumetric analyses of individual organs in adult zebrafish. Adipose tissues showed a higher affinity to iodine and were more strongly contrasted in microCT. As traditional histological techniques often involve dehydration steps that remove tissue lipids, iodine-contrasted microCT offers a convenient method for visualizing fat deposition in fish. Utilizing this advantage, we discovered a transient accumulation of lipids around the heart after ventricular amputation, suggesting a correlation between lipid distribution and heart regeneration. Taken together, microCT is a versatile technique that enables the 3D visualization of zebrafish organs, as well as other fish models, in their anatomical context. This simple method is a valuable new addition to the arsenal of techniques available to this model organism.

Laboratory and exterior decay of wood–plastic composite boards: voids analysis and computed tomography

ABSTRACTAfter exposure in the field and laboratory soil block culture testing, the void content of wood–plastic composite (WPC) decking boards was compared to unexposed samples. A void volume analysis was conducted based on calculations of sample density and from micro-computed tomography (microCT) data. It was found that reference WPC contains voids of different sizes from the micrometer range up to several cubic millimeters. Large voids were unevenly distributed within the composite sample. Void size and volume increased after conditioning the WPC in water at 70°C. Depending on the effect of exposure conditions, fungal decay during laboratory soil block testing increased the size and volume of voids. For laboratory samples, the calculated void volume was much higher compared to microCT-detected voids because of the limited resolution of the instrument on relatively large samples with many nano- and microvoids present in the material. In both laboratory and field samples, the creation of the voids resulted in a significant decrease in composite density. Decay damage observed as an increase in the size and volume of voids was particularly severe for boards exposed in the field. The calculated void volume in such samples was in reasonable agreement with voids detected by microCT.

Technical Note: Cortical thickness and density estimation from clinical CT using a prior thickness-density relationship.

Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed. Density variations across the cortex were modeled as a function of the cortical thickness and density, location of the cortex, density of surrounding tissues, and imaging blur. High resolution micro-CT data of cadaver proximal femurs were analyzed to determine a relationship between cortical thickness and density. This thickness-density relationship was used as prior information to be incorporated in the model to obtain accurate measurements of cortical thickness and density from clinical CT volumes. The method was validated using micro-CT scans of 23 cadaver proximal femurs. Simulated clinical CT images with different voxel sizes were generated from the micro-CT data. Cortical thickness and density were estimated from the simulated images using the proposed method and compared with measurements obtained using the micro-CT images to evaluate the effect of voxel size on the accuracy of the method. Then, 19 of the 23 specimens were imaged using a clinical CT scanner. Cortical thickness and density were estimated from the clinical CT images using the proposed method and compared with the micro-CT measurements. Finally, a case-control study including 20 patients with osteoporosis and 20 age-matched controls with normal bone density was performed to evaluate the proposed method in a clinical context. Cortical thickness (density) estimation errors were 0.07 ± 0.19 mm (-18 ± 92 mg/cm(3)) using the simulated clinical CT volumes with the smallest voxel size (0.33 × 0.33 × 0.5 mm(3)), and 0.10 ± 0.24 mm (-10 ± 115 mg/cm(3)) using the volumes with the largest voxel size (1.0 × 1.0 × 3.0 mm(3)). A trend for the cortical thickness and density estimation errors to increase with voxel size was observed and was more pronounced for thin cortices. Using clinical CT data for 19 of the 23 samples, mean errors of 0.18 ± 0.24 mm for the cortical thickness and 15 ± 106 mg/cm(3) for the density were found. The case-control study showed that osteoporotic patients had a thinner cortex and a lower cortical density, with average differences of -0.8 mm and -58.6 mg/cm(3) at the proximal femur in comparison with age-matched controls (p-value < 0.001). This method might be a promising approach for the quantification of cortical bone thickness and density using clinical routine imaging techniques. Future work will concentrate on investigating how this approach can improve the estimation of mechanical strength of bony structures, the prevention of fracture, and the management of osteoporosis.

Micro-CT image calibration to improve fracture aperture measurement

A novel technique for the accurate measurement and adjustment of fracture apertures in digital images of fractured media is presented. We utilize X-ray micro-computed tomography to image a highly fractured coal sample and collect high-resolution scanning electron microscope (SEM) images from the samples surface to facilitate segmentation of coal fractures. The gray-scale micro-CT values at the mid-point of fractures are obtained and correlated to aperture sizes measured with the higher resolution SEM data. Afterwards, the micro-CT images are upsampled to enable assignment of aperture sizes smaller than the image resolution. We initially segment the coal image, upsample the segmented image, and then re-calibrate the fracture aperture sizes. The final calibrated segmented image contains the fracture network acquired from the micro-CT data with precise aperture sizes assigned based on the high-resolution SEM data. To illustrate the importance of accurate aperture measurement, two coal subsets are tested. The permeabilities before and after applying the calibration method are measured. The results show a significant change in numerical permeabilities after applying the calibration method. This indicates that a large amount of information is potentially omitted when utilizing standard image segmentation tools to segment fractured media.

MicroCT assessment of bone microarchitecture in implant sites reconstructed with autogenous and xenogenous grafts: a pilot study.

To assess bone microarchitecture in maxillary sites grafted with autogenous or xenogenous grafts as well as to demonstrate the usefulness of microCT in dental implant research. Samples (n=12) consisting of titanium fixation screws covered by at least 0.5-1mm of human bone were obtained from 17 sites grafted with autogenous or xenogenous materials and prepared for microCT scanning and conventional histology. Bone histomorphometric parameters were evaluated in three distinct regions (graft region, transitional region, and native bone region). Three-dimensional (3D) bone-to-implant contact (BIC) calculation was performed using microCT data. Histological sections were used to calculate two-dimensional (2D) BIC percentages, which were compared with values obtained from 2D microCT images. Histomorphometric parameters varied according to the type of graft used, but sites reconstructed with autogenous bone showed higher mean values in general. In autograft samples, indices for parameters such as Tb.Th and Tb.Sp were significantly different when the native bone region was compared to the graft region. While a higher mean 3D BIC was found in the native bone region for both graft materials, significant BIC differences were absent when graft types were compared. The 2D BIC percentages obtained from histological and microCT images were similar. Autografts outperformed the xenogenous material used in this study concerning the histomorphometric parameters assessed. While graft type did not seem to influence 3D BIC, the native bone region showed the highest BIC percentages when compared to the other regions in both graft groups. In addition, 2D BIC ratios were similar regardless of graft material or image source (histological sections x microCT slices). Taken together, our findings suggest that microCT is an effective tool for 2D and 3D histomorphometric and BIC assessments in dental implant research.

Clinical utility of post-mortem micro-CT of the fetal heart: an exploratory study of diagnostic imaging versus macroscopic dissection

BackgroundCongenital cardiac malformations are commonly seen at perinatal autopsy. Accurate diagnosis can be challenging in small, macerated fetuses. The diagnostic accuracy of post-mortem MRI is diminished below 18 gestational weeks; however, micro-CT can provide micrometre resolution images but has not been evaluated for human diagnostic accuracy. We hypothesised that micro-CT could provide useful diagnostic information in fetal congenital heart disease and compared it with the gold standard of autopsy. MethodsReferrals to Great Ormond Street Hospital were prospectively included. Ex-vivo fetal hearts underwent micro-CT examination. 21 indices normally assessed at autopsy were evaluated for each heart at both micro-CT and autopsy in a single-masked fashion. All parents provided written consent for both autopsy, including post-mortem imaging, and research. The study was part of a larger study given ethics approval (IRAS ID 13942, R&D 09MH01). FindingsWe examined six fetal hearts including five with complex congenital cardiac malformations (17–23 weeks' gestation). Heart weights ranged between 1·1 g and 5·3 g (median 4·6 g). All specimens demonstrated excellent internal contrast at micro-CT examination, and the correct overall diagnosis was made from micro-CT data in all cases. There was agreement for 114 of 126 indices assessed on micro-CT and autopsy dissection (overall concordance 95·8% (95% CI 90·5–98·2). Micro-CT was particularly useful in the assessment of ventricular morphology in macerated fetuses. Micro-CT examination for diagnosis of complex congenital heart disease had a sensitivity of 85·2% (95% CI 67·5–94·1) and specificity of 98·9% (94·1–99·8). InterpretationOur preliminary study shows that micro-CT can provide diagnostically accurate three-dimensional volumes of complex congenital fetal heart disease. This approach potentially represents a substantial advance in post-mortem imaging and confirms the potential of this technology for non-invasive examination of small fetuses and organs. Centres that do not have specialist paediatric cardiac pathology expertise might especially benefit. Limitations include the small study size. Future studies should also include in-vivo post-mortem evaluation. FundingNone.

A method of determining bending properties of poultry long bones using beam analysis and micro-CT data

While conventional mechanical testing has been regarded as a gold standard for the evaluation of bone heath in numerous studies, with recent advances in medical imaging, virtual methods of biomechanics are rapidly evolving in the human literature. The objective of the current study was to evaluate the feasibility of determining the elastic and failure properties of poultry long bones using established methods of analysis from the human literature. In order to incorporate a large range of bone sizes and densities, a small number of specimens were utilized from an ongoing study of Regmi et al. (2016) that involved humeri and tibiae from 3 groups of animals (10 from each) including aviary, enriched, and conventional housing systems. Half the animals from each group were used for ‘training’ that involved the development of a regression equation relating bone density and geometry to bending properties from conventional mechanical tests. The remaining specimens from each group were used for ‘testing’ in which the mechanical properties from conventional tests were compared to those predicted by the regression equations. Based on the regression equations, the coefficients of determination for the ‘test’ set of data were 0.798 for bending bone stiffness and 0.901 for the yield (or failure) moment of the bones. All regression slopes and intercepts values for the tests versus predicted plots were not significantly different from 1 and 0, respectively. The study showed the feasibility of developing future methods of virtual biomechanics for the evaluation of poultry long bones. With further development, virtual biomechanics may have utility in future in vivo studies to assess laying hen bone health over time without the need to sacrifice large groups of animals at each time point.

Micro-Computed Tomography for the Quantitative 3-Dimensional Assessment of the Compact Myocardium in the Mouse Embryo.

Ventricular non-compaction is characterized by a thin layer of compact ventricular myocardium and it is an important abnormality in the mouse heart. It is reminiscent of left ventricular non-compaction, a fairly common human congenital cardiomyopathy. Non-compaction in transgenic mice has been classically evaluated by measuring the thickness of the compact myocardium through histological techniques involving image analysis of 2-dimensional (D) sections. Given the 3D nature of the heart, the aim of this study was to determine whether a technique for the non-destructive, 3D assessment of the mouse embryonic compact myocardium could be developed. Micro-computed tomography (micro-CT), in combination with iodine staining, enabled the differentiation of the trabecular from the compact myocardium in wild-type mice. The 3D and digital nature of the micro-CT data allowed computation anatomical techniques to be readily applied, which were demonstrated via construction of group atlases and atlas-based descriptive statistics. Finally, micro-CT was used to identify the presence of non-compaction in mice with a deletion of the cell cycle inhibitor protein, p27(Kip1). Iodine staining-enhanced micro-CT with computational anatomical analysis represents a valid addition to classical histology for the delineation of compact myocardial wall thickness in the mouse embryo. Given the quantitative 3D resolution of micro-CT, these approaches might provide helpful information for the analysis of non-compaction. (Circ J 2016; 80: 1795-1803).

Dosimetry in small-animal CT using Monte Carlo simulations

Small-animal computed tomography (micro-CT) imaging devices are increasingly being used in biological research. While investigators are mainly interested in high-contrast, low-noise, and high-resolution anatomical images, relatively large radiation doses are required, and there is also growing concern over the radiological risk from preclinical experiments. This study was conducted to determine the radiation dose in a mouse model for dosimetric estimates using the GEANT4 application for tomographic emission simulations (GATE) and to extend its techniques to various small-animal CT applications. Radiation dose simulations were performed with the same parameters as those for the measured micro-CT data, using the MOBY phantom, a pencil ion chamber and an electrometer with a CT detector. For physical validation of radiation dose, absorbed dose of brain and liver in mouse were evaluated to compare simulated results with physically measured data using thermoluminescent dosimeters (TLDs). The mean difference between simulated and measured data was less than 2.9% at 50 kVp X-ray source. The absorbed doses of 37 brain tissues and major organs of the mouse were evaluated according to kVp changes. The absorbed dose over all of the measurements in the brain (37 types of tissues) consistently increased and ranged from 42.4 to 104.0 mGy. Among the brain tissues, the absorbed dose of the hypothalamus (157.8–414.30 mGy) was the highest for the beams at 50–80 kVp, and that of the corpus callosum (11.2–26.6 mGy) was the lowest. These results can be used as a dosimetric database to control mouse doses and preclinical targeted radiotherapy experiments. In addition, to accurately calculate the mouse-absorbed dose, the X-ray spectrum, detector alignment, and uncertainty in the elemental composition of the simulated materials must be accurately modeled.