A braided stent becomes flattened inside a curved catheter tube: A micro-CT imaging study

2020 ◽  
Vol 31 (6) ◽  
pp. 373-380
Author(s):  
Taiki Shigematsu ◽  
Tomohiro Otani ◽  
Shotaro Tomotake ◽  
Shunya Shiozaki ◽  
Shigeo Wada
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Imaging Study ◽  
Outer Side ◽  
Micro Ct ◽  
Mechanical State ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Catheter Tube ◽  
Braided Stent

BACKGROUND: The braided stent is a widely accepted endovascular treatment device consisting of woven metal wires. One of the unsolved issues for the braided stent is the stent flattening phenomena when deployed into highly curved arteries. Although a recent computational study highlighted that the mechanical state of the stent inside the catheter before the deployment plays an essential role in causing stent flattening, there is no experimental observation for the stent inside the curved catheter. OBJECTIVE: We investigated braided stent shapes in curved catheter tubes with various curvatures by micro-computed tomography (CT). METHODS: A braided stent was deployed into catheter tubes and set in rectangular cases with constant curvature. The three-dimensional shape of the stent was imaged by micro-CT, and its cross-sectional flatness was quantitatively assessed. RESULTS: Stent flattening occurred in cases of high curvatures of the outer side of the tube curvature, and the degree of flatness increased with increasing tube curvature. This demonstrates that stent flattening can be caused inside the highly curved catheter before deployment. CONCLUSIONS: This preliminary and first observational report provides new insight into the mechanism of stent flattening and emphasizes the importance of the geometrical and mechanical state of the stent inside the catheter.

scholarly journals Micro-computed tomography: A novel diagnostic technique for the evaluation of gastrointestinal specimens

2021 ◽  
Vol 09 (12) ◽  
pp. E1886-E1889
Author(s):  
Noboru Kawata ◽  
Alexei Teplov ◽  
Peter Ntiamoah ◽  
Jinru Shia ◽  
Meera Hameed ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Diagnostic Technique ◽  
Human Colon ◽  
Ffpe Tissue ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Tissue Samples ◽  
Formalin Fixed Paraffin Embedded

AbstractMicro-computed tomography (micro-CT) is a non-destructive modality that can be used to obtain high-resolution three-dimensional (3 D) images of the whole sample tissue; the usefulness of micro-CT has been reported for evaluation of breast cancer and lung cancer. However, this novel diagnostic technique has never been used for evaluating endoscopically resected gastrointestinal specimens. In the present study, we scanned 13 formalin-fixed paraffin-embedded (FFPE) tissue blocks of a normal human colon and gastric tissue samples using micro-CT. The evaluation comprised a comparison of the acquired whole block images with the images of the corresponding cross-sectional slice of the hematoxylin and eosin-stained slide. Micro-CT was able to produce images of the whole sample and clearly depict tissues such as glandular structures, muscularis mucosae, and blood vessels in the FFPE tissue blocks of normal gastrointestinal samples. Furthermore, the 3 D reconstructed could be used to create a cross-sectional image and reflected the surface structure of samples obtained from any site. Micro-CT has the potential to become a highly promising pathological diagnostic assistance tool for endoscopically resected gastrointestinal specimens in combination with conventional microscopic examination.

scholarly journals Three-dimensional Quantitative Porosity Characterization of Syringe- versus Hand-mixed Set Epoxy Resin Root Canal Sealer

2015 ◽  
Vol 26 (6) ◽  
pp. 607-611 ◽  
Author(s):  
Gustavo De-Deus ◽  
Miriam Z. Scelza ◽  
Prasanna Neelakantan ◽  
Subash Sharma ◽  
Aline de Almeida Neves ◽  
...  
Keyword(s):  
Pore Volume ◽  
Root Canal ◽  
External Surface ◽  
Three Dimensional ◽  
Total Pore Volume ◽  
Total Porosity ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Ah Plus

The aim of the present study was to compare the porosity characteristics of AH Plus Jet(tm) syringe-mix and the conventional hand-mixed AH Plus root canal sealers by three-dimensional quantitative high-resolution micro-computed tomography (micro-CT). Seven test specimens were prepared from each tested sealer by a single operator following the manufacturer's instructions and poured into pre-lubricated plastic split-ring moulds. Set sealer test specimens were scanned using a micro-CT device and the shadow images were reconstructed into cross-sectional slices. The evaluated parameters were (i) total pore count, (ii) total pore volume and mean pore volume, (iii) total porosity (% of pore volume in relation to total sealer volume) and (iv) mean pore distance to the sealer lateral external surface. In both groups, most pores were localized within the external sealer perimeter (0.05 mm from the external surface). Hand-mixed AH Plus specimens showed statistically significant higher mean total pore count, total pore volume and total porosity (p=0.001) than the syringe-mixed specimens. However, mean pore sizes in AH Plus syringe-mixed specimens were significantly higher (p=0.046) than the AH Plus hand-mixed counterparts. Hand-mixed AH Plus was associated with higher total mean pore count, volume and total porosity compared to syringe mixed AH Plus.

scholarly journals Heterogeneous and anisotropic integrative model of pulmonary veins: computational study of arrhythmogenic substrate for atrial fibrillation

2013 ◽  
Vol 3 (2) ◽  
pp. 20120069 ◽  
Author(s):  
Oleg V. Aslanidi ◽  
Michael A. Colman ◽  
Marta Varela ◽  
Jichao Zhao ◽  
Bruce H. Smaill ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
High Frequency ◽  
Computational Study ◽  
Pulmonary Veins ◽  
Three Dimensional ◽  
Primary Source ◽  
Integrative Model ◽  
Micro Computed Tomography ◽  
Three Dimensional Model ◽  
Arrhythmogenic Substrate

Mechanisms underlying the genesis of re-entrant substrate for the most common cardiac arrhythmia, atrial fibrillation (AF), are not well understood. In this study, we develop a multi-scale three-dimensional computational model that integrates cellular electrophysiology of the left atrium (LA) and pulmonary veins (PVs) with the respective tissue geometry and fibre orientation. The latter is reconstructed in unique detail from high-resolution (approx. 70 μm) contrast micro-computed tomography data. The model is used to explore the mechanisms of re-entry initiation and sustenance in the PV region, regarded as the primary source of high-frequency electrical activity in AF. Simulations of the three-dimensional model demonstrate that an initial break-down of normal electrical excitation wave-fronts can be caused by the electrical heterogeneity between the PVs and LA. High tissue anisotropy is then responsible for the slow conduction and generation of a re-entrant circuit near the PVs. Evidence of such circuits has been seen clinically in AF patients. Our computational study suggests that primarily the combination of electrical heterogeneity and conduction anisotropy between the PVs and LA tissues leads to the generation of a high-frequency (approx. 10 Hz) re-entrant source near the PV sleeves, thus providing new insights into the arrhythmogenic mechanisms of excitation waves underlying AF.

scholarly journals PEG-modified gadolinium nanoparticles as contrast agents for in vivo micro-CT

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charmainne Cruje ◽  
P. Joy Dunmore-Buyze ◽  
Eric Grolman ◽  
David W. Holdsworth ◽  
Elizabeth R. Gillies ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Contrast Agents ◽  
Soft Tissues ◽  
Three Dimensional ◽  
Blood Pool ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Poly Ethylene

AbstractVascular research is largely performed in rodents with the goal of developing treatments for human disease. Micro-computed tomography (micro-CT) provides non-destructive three-dimensional imaging that can be used to study the vasculature of rodents. However, to distinguish vasculature from other soft tissues, long-circulating contrast agents are required. In this study, we demonstrated that poly(ethylene glycol) (PEG)-coated gadolinium nanoparticles can be used as a vascular contrast agent in micro-CT. The coated particles could be lyophilized and then redispersed in an aqueous solution to achieve 100 mg/mL of gadolinium. After an intravenous injection of the contrast agent into mice, micro-CT scans showed blood pool contrast enhancements of at least 200 HU for 30 min. Imaging and quantitative analysis of gadolinium in tissues showed the presence of contrast agent in clearance organs including the liver and spleen and very low amounts in other organs. In vitro cell culture experiments, subcutaneous injections, and analysis of mouse body weight suggested that the agents exhibited low toxicity. Histological analysis of tissues 5 days after injection of the contrast agent showed cytotoxicity in the spleen, but no abnormalities were observed in the liver, lungs, kidneys, and bladder.

StyroStone: A protocol for scanning and extracting three-dimensional meshes of stone artefacts using Micro-CT scanners v1

2021 ◽  
Author(s):  
Dominik Göldner ◽  
Fotios Alexandros Karakostis ◽  
Armando Falcucci
Keyword(s):  
Three Dimensional ◽  
Computation Time ◽  
Ct Scanning ◽  
3D Models ◽  
Stone Tools ◽  
Surface Model ◽  
Micro Ct ◽  
Ct Scanner ◽  
Micro Computed Tomography ◽  
Ct Scanners

This protocol presents the first detailed step-by-step pipeline for the 3D scanning and post processing of large batches of lithic artefacts using a micro-computed tomography (micro-CT) scanner (i.e., a Phoenix v-tome-x S model by General Electronics MCC, Boston MA) and an Artec Space Spider scanner (Artec Inc., Luxembourg). This protocol was used to scan and analyze ca. 700 lithic artefacts from the Protoaurignacian layers at Fumane Cave in north-eastern Italy (Falcucci et al., in preparation). For this study several costly scanners and proprietary software packages were employed. Although it is not easy to find a low-budget alternative for the scanners, it is possible to use free and open-source software programs, such as 3D-Slicer (https://www.slicer.org/) or MorphoDig (https://morphomuseum.com/morphodig), to process CT data as well as MeshLab (Cignoni et al. 2008) to interact with the 3D models in general. However, if alternative software is used, the steps and their order described in this protocol might diverge significantly. A cost-effective alternative to create 3D models is digital photogrammetry using commercial cameras and freely available software like Meshroom (https://alicevision.org). Although photogrammetry is an affordable technique to create accurate 3D models of objects, this method might not be useful when scanning large batches of artefacts, as it will require a lot of computation time and processing capacity. Likewise, it could be difficult to generate accurate 3D models of very small and/or detailed tool shapes using 3D surface scanners because stone tools are often much smaller than the recommended minimum field of view. Similarly, the resolution of conventional medical CT scanners might not be sufficient to capture minor details of stone tools, such as the outline or dorsal scars. Thus, high-resolution micro-CT technology is the only reliable way to accurately capture the overall morphology of small stone tools. This protocol aims at providing the first detailed procedure dedicated to the scanning of small lithic implements for further three-dimensional analysis. Note that some of the steps must be repeated at different working stages throughout this protocol. In cases where a task must be done in the exact same way as described in a previous step, a reference to that step is provided. When slight changes were made, the step was modified and reported entirely. This protocol contains a few red and green colours (e.g., arrows or within-program colours) which might be perceived differently by people with dyschromatopsia. However, the display of these colours has been kept to a minimum. We recommend the reader to go over the entire protocol carefully, even if only some specific parts are required. A few points are in fact interdependent, and some of them must be applied simultaneously. Content: Part 1 – Styrofoam preparation Part 2 – Micro-CT scanning Part 3 – 3D model extraction of CT scanned stone artifacts using Avizo Part 4 – Cropping extracted surface model to separate Face A and B in Artec Studio Part 5 – Cropping Face A to separate the lines in Artec Studio Part 6 – Cropping each stone artefact from the lines in Artec Studio Part 7 – Virtually control measurements in MeshLab Part 8 – Artec scanning of larger artifacts Part 9 – Export meshes as non-binary ply models for successive analysis in geomorph Three-dimensional example (in ply format) of the effectivity of the StyroStone Protocol: You can download an example of one Styrofoam line in 3D obtained using our protocol to appreciate the result that can be achieved. We have selected a line where objects are characterized by different metric and morphological attributes. Notice the retouching well visible in the last five smaller artifacts (counting from the left when artifact are oriented with the dorsal face in front of the observer and the butt down), as well as the platforms and bulbs of all artifacts. For more information and examples, feel free to contact us!

scholarly journals Micro-CT study of Middle Ordovician Spumellaria (radiolarians) from western Newfoundland, Canada

2020 ◽  
Vol 94 (3) ◽  
pp. 417-435 ◽  
Author(s):  
Sarah Kachovich ◽  
Jonathan C. Aitchison
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Detailed Examination ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Lower Paleozoic ◽  
X Ray ◽  
Middle Ordovician ◽  
Radiolarian Assemblage ◽  
Taxonomic Groups

AbstractA new, previously undescribed Middle Ordovician (middle Darriwilian: Dw2) radiolarian assemblage has been recovered from the Table Cove Formation at Piccadilly Quarry, western Newfoundland. Constituents of the fauna described herein are both distinctive and exceptionally well preserved. Three-dimensional X-ray micro-computed tomography (μ-CT) is used to make a detailed examination of four key spumellarian specimens. This technology enables visualization of hitherto ambiguous details of the internal morphologies of key lower Paleozoic taxonomic groups, among which a lack of knowledge has impeded resolution of higher taxonomic rankings.

scholarly journals Automated segmentation of insect anatomy from micro-CT images using deep learning

2021 ◽  
Author(s):  
Evropi Toulkeridou ◽  
Carlos Enrique Gutierrez ◽  
Daniel Baum ◽  
Kenji Doya ◽  
Evan P Economo
Keyword(s):  
Deep Learning ◽  
Brain Area ◽  
Three Dimensional ◽  
Neural System ◽  
Ct Images ◽  
Automated Segmentation ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Anatomical Structures ◽  
Trained Network

Three-dimensional (3D) imaging, such as micro-computed tomography (micro-CT), is increasingly being used by organismal biologists for precise and comprehensive anatomical characterization. However, the segmentation of anatomical structures remains a bottleneck in research, often requiring tedious manual work. Here, we propose a pipeline for the fully-automated segmentation of anatomical structures in micro-CT images utilizing state-of-the-art deep learning methods, selecting the ant brain as a testcase. We implemented the U-Net architecture for 2D image segmentation for our convolutional neural network (CNN), combined with pixel-island detection. For training and validation of the network, we assembled a dataset of semi-manually segmented brain images of 94 ant species. The trained network predicted the brain area in ant images fast and accurately; its performance tested on validation sets showed good agreement between the prediction and the target, scoring 80% Intersection over Union(IoU) and 90% Dice Coefficient (F1) accuracy. While manual segmentation usually takes many hours for each brain, the trained network takes only a few minutes.Furthermore, our network is generalizable for segmenting the whole neural system in full-body scans, and works in tests on distantly related and morphologically divergent insects (e.g., fruit flies). The latter suggest that methods like the one presented here generally apply across diverse taxa. Our method makes the construction of segmented maps and the morphological quantification of different species more efficient and scalable to large datasets, a step toward a big data approach to organismal anatomy.

scholarly journals Distal Placement of an End-to-Side Bypass Graft Anastomosis: A 3-D Computational Study

2005 ◽  
Author(s):  
John R. DiCicco ◽  
Ayodeji O. Demuren
Keyword(s):  
Stokes Equations ◽  
Computational Study ◽  
Bypass Graft ◽  
Three Dimensional ◽  
Rate Equations ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Shear Rates ◽  
Lower Shear ◽  
Hexahedral Elements

A three-dimensional (3-D) computational fluid dynamics study of shear rates around distal end-to-side anastomoses has been conducted. Three 51% and three 75% cross-sectional area reduced 6 mm cylinders were modeled each with a bypass cylinder attached at a 30 degree angle at different placements distal to the constriction. Steady, incompressible, Newtonian blood flow was assumed, and the full Reynolds-averaged Navier-Stokes equations and turbulent kinetic energy and specific dissipation rate equations were solved on a locally structured multi-block mesh with hexahedral elements. Consequently, distal placement of an end-to-side bypass graft anastomosis was found to have an influence on the shear rate magnitudes. For the 75% constriction, closer placements produced lower shear rates near the anastomosis. Hence, there is potential for new plaque formation and graft failure.

scholarly journals Anatomic development of the upper airway during the first five years of life: A three-dimensional imaging study

2021 ◽  
Author(s):  
Ying Ji Chuang ◽  
Seong Jae Hwang ◽  
Kevin A Buhr ◽  
Courtney A Miller ◽  
Gregory D Avey ◽  
...  
Keyword(s):  
Data Extraction ◽  
Three Dimensional ◽  
Upper Airway ◽  
Imaging Study ◽  
Typically Developing ◽  
Cross Sectional ◽  
Airway Segmentation ◽  
Methodological Considerations ◽  
2D And 3D ◽  
Position Histogram

Purpose. Normative data on the growth and development of the upper airway across the sexes is needed for the diagnosis and treatment of congenital and acquired respiratory anomalies and to gain insight on developmental changes in speech acoustics and disorders with craniofacial anomalies. Methods. The growth of the upper airway in children ages birth-to-five years, as compared to adults, was quantified using an imaging database with computed tomography studies from typically developing individuals. Methodological criteria for scan inclusion and airway measurements included: head position, histogram-based airway segmentation, anatomic landmark placement, and development of a semi-automatic centerline for data extraction. A comprehensive set of 2D and 3D supra- and sub-glottal measurements from the choanae to tracheal opening were obtained including: naso-oro-laryngo-pharynx subregion volume and length, each subregion superior and inferior cross-sectional-area, and antero-posterior and transverse/width distances. Results. Growth of the upper airway during the first five years of life was more pronounced in the vertical and transverse/lateral dimensions than in the antero-posterior dimension. By age five years, females have larger pharyngeal measurement than males. Prepubertal sex-differences were identified in the subglottal region. Conclusions. Our findings demonstrate the importance of studying the growth of the upper airway in 3D. As the lumen length increases, its shape changes, becoming increasingly elliptical during the first five years of life. This study also emphasizes the importance of methodological considerations for both image acquisition and data extraction, as well as the use of consistent anatomic structures in defining pharyngeal regions.

Upscaling Reservoir Rock Porosity by Fractal Dimension Using Three-Dimensional Micro-Computed Tomography and Two-Dimensional Scanning Electron Microscope Images

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Muhammad Jawad Munawar ◽  
Sandra Vega ◽  
Chengyan Lin ◽  
Mohammad Alsuwaidi ◽  
Naveed Ahsan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Fractal Dimensions ◽  
Two Dimensional ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Sandstone Sample ◽  
The Core ◽  
Carbonate Sample ◽  
Scanning Electron

Abstract Scaling porosity of sedimentary rocks from the scale of measurement to the scale of interest is still a challenge. Upscaling of porosity can assist to accurately predict other petrophysical properties of rock at multiple scales. In this study, we use the two-dimensional (2D) scanning electron microscope (SEM) and three-dimensional (3D) X-ray micro-computed tomography (micro-CT) image to upscale porosity from the image scale to the core plug scale. A systematic imaging plan is deployed to capture rock properties of a carbonate and a sandstone sample, which are sensitive to the fractal nature of these rocks. Image analysis records wider pore spectrum (0.12–50 µm) in the carbonate sample than in sandstone (0.12–30 µm). The fractal dimensions are also higher in the carbonate than in the sandstone sample. Median, volume-weighted average of pore radius, and fractal dimensions derived from the image analysis are used as inputs in this equation. The results of the present study using this equation yielded to the best results on a resolution of 2.5 µm/voxel in the sandstone and 2.01 µm/voxel resolution in the carbonate sample for 3D micro-CT images, where fractal-scaling porosity matches well with the porosity measured at the core plug scale. The 2D SEM images provided a good estimation of porosity in the sandstone sample, where micro-CT imaging techniques could not capture the full pore spectrum. The fractal porosity equation showed promising results and offers a potential alternative way to estimate porosity when there are no routine core measurements available.

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