scholarly journals Automated segmentation of the lamina cribrosa using Frangi's filter: a novel approach for rapid identification of tissue volume fraction and beam orientation in a trabeculated structure in the eye

2015 ◽  
Vol 12 (104) ◽  
pp. 20141009 ◽  
Author(s):  
Ian C. Campbell ◽  
Baptiste Coudrillier ◽  
Johanne Mensah ◽  
Richard L. Abel ◽  
C. Ross Ethier
Keyword(s):  
Connective Tissue ◽  
Volume Fraction ◽  
Second Harmonic ◽  
Imaging Techniques ◽  
Lamina Cribrosa ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Tissue Volume

The lamina cribrosa (LC) is a tissue in the posterior eye with a complex trabecular microstructure. This tissue is of great research interest, as it is likely the initial site of retinal ganglion cell axonal damage in glaucoma. Unfortunately, the LC is difficult to access experimentally, and thus imaging techniques in tandem with image processing have emerged as powerful tools to study the microstructure and biomechanics of this tissue. Here, we present a staining approach to enhance the contrast of the microstructure in micro-computed tomography (micro-CT) imaging as well as a comparison between tissues imaged with micro-CT and second harmonic generation (SHG) microscopy. We then apply a modified version of Frangi's vesselness filter to automatically segment the connective tissue beams of the LC and determine the orientation of each beam. This approach successfully segmented the beams of a porcine optic nerve head from micro-CT in three dimensions and SHG microscopy in two dimensions. As an application of this filter, we present finite-element modelling of the posterior eye that suggests that connective tissue volume fraction is the major driving factor of LC biomechanics. We conclude that segmentation with Frangi's filter is a powerful tool for future image-driven studies of LC biomechanics.

scholarly journals Micro-CT for Biological and Biomedical Studies: A Comparison of Imaging Techniques

2021 ◽  
Vol 7 (9) ◽  
pp. 172
Author(s):  
Kleoniki Keklikoglou ◽  
Christos Arvanitidis ◽  
Georgios Chatzigeorgiou ◽  
Eva Chatzinikolaou ◽  
Efstratios Karagiannidis ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Imaging Techniques ◽  
Laser Scanning Microscopy ◽  
Three Dimensions ◽  
Morphological Data ◽  
Confocal Laser ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Non Destructive ◽  
Great Resolution

Several imaging techniques are used in biological and biomedical studies. Micro-computed tomography (micro-CT) is a non-destructive imaging technique that allows the rapid digitisation of internal and external structures of a sample in three dimensions and with great resolution. In this review, the strengths and weaknesses of some common imaging techniques applied in biological and biomedical fields, such as optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy, are presented and compared with the micro-CT technique through five use cases. Finally, the ability of micro-CT to create non-destructively 3D anatomical and morphological data in sub-micron resolution and the necessity to develop complementary methods with other imaging techniques, in order to overcome limitations caused by each technique, is emphasised.

scholarly journals Correlation between Local Stress and Strain and Lamina Cribrosa Connective Tissue Volume Fraction in Normal Monkey Eyes

2010 ◽  
Vol 51 (1) ◽  
pp. 295 ◽  
Author(s):  
Michael D. Roberts ◽  
Yi Liang ◽  
Ian A. Sigal ◽  
Jonathan Grimm ◽  
Juan Reynaud ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Volume Fraction ◽  
Local Stress ◽  
Lamina Cribrosa ◽  
Stress And Strain ◽  
Tissue Volume ◽  
Normal Monkey

Quantitative micro-computed tomography analysis and rheological investigation of Nitrile rubber/Rockwool composites

2021 ◽  
pp. 002199832110338
Author(s):  
Elisson BD da Rocha ◽  
Ana Maria F de Sousa ◽  
Ana Lúcia N da Silva ◽  
Cristina RG Furtado ◽  
Marcos V Colaço ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Elastic Modulus ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Nitrile Rubber ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Rubber Composites ◽  
Ratio Data ◽  
Ct Analysis

This study reports the reinforcement degree investigation of two types of rockwool fibers (F1 and F2), in nitrile rubber composites. The micro-computed tomography (micro-CT) 3D images showed that both fibers were well-dispersed in the NBR matrix, without a preferential orientation. The micro-CT analysis also allowed quantifying volume fraction, inter-fiber distance, and aspect ratio. Those morphometric parameters were used for supporting the composites rheological behavior assessment. Changes in the elastic modulus and phase angle followed the same trend of the inter-fiber distance values, regardless the type of fiber. Both volume fraction and aspect ratio data from the micro-CT analysis were used to predict theoretical values of elastic modulus using the Guth-Gold and modified Guth-Gold equations, and the results obtained were compared to the rheological experimental data. This analysis was helpful to better understand the rockwool fibers reinforcement degree differences in the production of the nitrile rubber composites.

scholarly journals Combined Numerical-Statistical Analyses of Damage and Failure of 2D and 3D Mesoscale Heterogeneous Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Xiaofeng Wang ◽  
Andrey P. Jivkov
Keyword(s):  
Cohesive Zone Model ◽  
Volume Fraction ◽  
Simulation Method ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Zone Model ◽  
Generation Process ◽  
Cohesive Elements ◽  
Damage And Failure ◽  
2D And 3D

Generation and packing algorithms are developed to create models of mesoscale heterogeneous concrete with randomly distributed elliptical/polygonal aggregates and circular/elliptical voids in two dimensions (2D) or ellipsoidal/polyhedral aggregates and spherical/ellipsoidal voids in three dimensions (3D). The generation process is based on the Monte Carlo simulation method wherein the aggregates and voids are generated from prescribed distributions of their size, shape, and volume fraction. A combined numerical-statistical method is proposed to investigate damage and failure of mesoscale heterogeneous concrete: the geometrical models are first generated and meshed automatically, simulated by using cohesive zone model, and then results are statistically analysed. Zero-thickness cohesive elements with different traction-separation laws within the mortar, within the aggregates, and at the interfaces between these phases are preinserted inside solid element meshes to represent potential cracks. The proposed methodology provides an effective and efficient tool for damage and failure analysis of mesoscale heterogeneous concrete, and a comprehensive study was conducted for both 2D and 3D concrete in this paper.

scholarly journals A new magnetic resonance-based technique for high-resolution quantification of amorphous and quasi-amorphous structures

2016 ◽  
Vol 13 (123) ◽  
pp. 20160589
Author(s):  
James Rafferty ◽  
Lance Farr ◽  
Tim James ◽  
David Chase ◽  
John Heinrich ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
High Resolution ◽  
Ex Vivo ◽  
Imaging Techniques ◽  
Three Dimensions ◽  
Small Scale ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Biological Structures ◽  
The One

We present a novel, high-resolution magnetic resonance technique, fine structure analysis (FSA) for the quantification and analysis of amorphous and quasi-amorphous biological structures. The one-dimensional technique is introduced mathematically and then applied to one simulated phantom, two physical phantoms and a set of ex vivo biological samples, scanned with interpoint spacings of 0.0038–0.195 mm and cross-sectional sizes of 3 × 3 or 5 × 5 mm. The simulated phantom and one of the physical phantoms consists of randomly arranged beads of known size in two and three dimensions, respectively. The second physical phantom was constructed by etching lines on Perspex. The ex vivo samples are human bone specimens. We show that for all three phantoms, the FSA technique is able to elucidate the average spacing of the structures present within each sample using structural spectroscopy, the smallest of which was 180 µm in size. We further show that in samples of trabecular bone, FSA is able to produce comparable results to micro-computed tomography, the current gold standard for measuring bone microstructure, but without the need for ionizing radiation. Many biological structures are too small to be captured by conventional, clinically deployed medical imaging techniques. FSA has the potential for use in the analysis of pathologies where such small-scale repeating structures are disrupted or their size, and spacing is otherwise altered.

scholarly journals Imaging Techniques for the Assessment of the Bone Osteoporosis-Induced Variations with Particular Focus on Micro-CT Potential

2020 ◽  
Vol 10 (24) ◽  
pp. 8939
Author(s):  
Giulia Molino ◽  
Giorgia Montalbano ◽  
Carlotta Pontremoli ◽  
Sonia Fiorilli ◽  
Chiara Vitale-Brovarone
Keyword(s):  
Fracture Risk ◽  
Imaging Techniques ◽  
Image Resolution ◽  
Osteoporotic Bone ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Mineral Density ◽  
Gold Standard Method ◽  
Long Time ◽  
Technological Improvements

For long time, osteoporosis (OP) was exclusively associated with an overall bone mass reduction, leading to lower bone strength and to a higher fracture risk. For this reason, the measurement of bone mineral density through dual X-ray absorptiometry was considered the gold standard method for its diagnosis. However, recent findings suggest that OP causes a more complex set of bone alterations, involving both its microstructure and composition. This review aims to provide an overview of the most evident osteoporosis-induced alterations of bone quality and a résumé of the most common imaging techniques used for their assessment, at both the clinical and the laboratory scale. A particular focus is dedicated to the micro-computed tomography (micro-CT) due to its superior image resolution, allowing the execution of more accurate morphometric analyses, better highlighting the architectural alterations of the osteoporotic bone. In addition, micro-CT has the potential to perform densitometric measurements and finite element method analyses at the microscale, representing potential tools for OP diagnosis and for fracture risk prediction. Unfortunately, technological improvements are still necessary to reduce the radiation dose and the scanning duration, parameters that currently limit the application of micro-CT in clinics for OP diagnosis, despite its revolutionary potential.

scholarly journals The Characteristics of Vascular Growth in VX2 Tumor Measured by MRI and Micro-CT

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
X.-L. Qi ◽  
J. Liu ◽  
P. N. Burns ◽  
G. A. Wright
Keyword(s):  
Volume Fraction ◽  
Tumor Model ◽  
Response To Therapy ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Tumor Vascularity ◽  
Vx2 Tumor ◽  
Relative Blood Volume

Blood supply is crucial for rapid growth of a malignant tumor; medical imaging can play an important role in evaluating the vascular characterstics of tumors. Magnetic resonance imaging (MRI) and micro-computed tomography (CT) are able to detect tumors and measure blood volumes of microcirculation in tissue. In this study, we used MR imaging and micro-CT to assess the microcirculation in a VX2 tumor model in rabbits. MRI characterization was performed using the intravascular contrast agent Clariscan (NC100150-Injection); micro-CT with Microfil was used to directly depict blood vessels with diameters as low as 17 um in tissue. Relative blood volume fraction (rBVF) in the tumor rim and blood vessel density (rBVD) over the whole tumor was calculated using the two imaging methods. Our study indicates that rBVF is negatively related to the volume of the tumor measured by ultrasound (R=0.90). rBVF in the tissue of a VX2 tumor measured by MRIin vivowas qualitatively consistent with the rBVD demonstrated by micro-CTin vitro(R=0.97). The good correlation between the two methods indicates that MRI studies are potentially valuable for assessing characteristics or tumor vascularity and for assessing response to therapy noninvasively.

scholarly journals Techniques to assess bone ultrastructure organization: orientation and arrangement of mineralized collagen fibrils

2016 ◽  
Vol 13 (119) ◽  
pp. 20160088 ◽  
Author(s):  
Marios Georgiadis ◽  
Ralph Müller ◽  
Philipp Schneider
Keyword(s):  
Ex Vivo ◽  
Imaging Techniques ◽  
Building Blocks ◽  
Two Dimensions ◽  
Collagen Fibrils ◽  
Three Dimensions ◽  
X Rays ◽  
Bone Ultrastructure ◽  
Mineralized Collagen

Bone's remarkable mechanical properties are a result of its hierarchical structure. The mineralized collagen fibrils, made up of collagen fibrils and crystal platelets, are bone's building blocks at an ultrastructural level. The organization of bone's ultrastructure with respect to the orientation and arrangement of mineralized collagen fibrils has been the matter of numerous studies based on a variety of imaging techniques in the past decades. These techniques either exploit physical principles, such as polarization, diffraction or scattering to examine bone ultrastructure orientation and arrangement, or directly image the fibrils at the sub-micrometre scale. They make use of diverse probes such as visible light, X-rays and electrons at different scales, from centimetres down to nanometres. They allow imaging of bone sections or surfaces in two dimensions or investigating bone tissue truly in three dimensions, in vivo or ex vivo , and sometimes in combination with in situ mechanical experiments. The purpose of this review is to summarize and discuss this broad range of imaging techniques and the different modalities of their use, in order to discuss their advantages and limitations for the assessment of bone ultrastructure organization with respect to the orientation and arrangement of mineralized collagen fibrils.

scholarly journals Stereology and three-dimensional reconstructions to analyze the pulmonary vasculature

2021 ◽  
Author(s):  
Christian Mühlfeld
Keyword(s):  
Blood Vessels ◽  
Lung Diseases ◽  
Imaging Techniques ◽  
Research Work ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Pulmonary Vasculature ◽  
Chronic Obstructive ◽  
Micro Computed Tomography ◽  
Arterial Tree

AbstractThe pulmonary vasculature consists of a large arterial and venous tree with a vast alveolar capillary network (ACN) in between. Both conducting blood vessels and the gas-exchanging capillaries are part of important human lung diseases, including bronchopulmonary dysplasia, pulmonary hypertension and chronic obstructive pulmonary disease. Morphological tools to investigate the different parts of the pulmonary vasculature quantitatively and in three dimensions are crucial for a better understanding of the contribution of the blood vessels to the pathophysiology and effects of lung diseases. In recent years, new stereological methods and imaging techniques have expanded the analytical tool box and therefore the conclusive power of morphological analyses of the pulmonary vasculature. Three of these developments are presented and discussed in this review article, namely (1) stereological quantification of the number of capillary loops, (2) serial block-face scanning electron microscopy of the ACN and (3) labeling of branching generations in light microscopic sections based on arterial tree segmentations of micro-computed tomography data sets of whole lungs. The implementation of these approaches in research work requires expertise in lung preparation, multimodal imaging at different scales, an advanced IT infrastructure and expertise in image analysis. However, they are expected to provide important data that cannot be obtained by previously existing methodology.

scholarly journals Micro-computed tomography for natural history specimens: a handbook of best practice protocols

2019 ◽  
Author(s):  
Kleoniki Keklikoglou ◽  
Sarah Faulwetter ◽  
Eva Chatzinikolaou ◽  
Patricia Wils ◽  
Jonathan Brecko ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Natural History ◽  
Best Practice ◽  
Ct Imaging ◽  
Three Dimensions ◽  
X Rays ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Ct Technology ◽  
Non Destructive

Micro-computed tomography (micro-CT or microtomography) is a non-destructive imaging technique using X-rays which allows the digitisation of an object in three dimensions. The ability of micro-CT imaging to visualise both internal and external features of an object, without destroying the specimen, makes the technique ideal for the digitisation of valuable natural history collections. This handbook serves as a comprehensive guide to laboratory micro-CT imaging of different types of natural history specimens, including zoological, botanical, palaeontological and geological samples. The basic principles of the micro-CT technology are presented, as well as protocols, tips and tricks and use cases for each type of natural history specimen. Finally, data management protocols and a comprehensive list of institutions with micro-CT facilities, micro-CT manufacturers and relative software are included.

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