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Patrick Segers - One of the best experts on this subject based on the ideXlab platform.
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Corrosion Casting of the cardiovascular structure in adult zebrafish for analysis by scanning electron microscopy and x ray microtomography
Anatomia Histologia Embryologia, 2020Co-Authors: Ward De Spiegelaere, Patrick Segers, Lisa Caboor, Matthias Van Impe, Matthieu Boone, Julie De Backer, Patrick SipsAbstract:Zebrafish have come to the forefront as a flexible, relevant animal model to study human disease, including cardiovascular disorders. Zebrafish are optically transparent during early developmental stages, enabling unparalleled imaging modalities to examine cardiovascular structure and function in vivo and ex vivo. At later stages, however, the options for systematic cardiovascular phenotyping are more limited. To visualise the complete vascular tree of adult zebrafish, we have optimised a vascular Corrosion Casting method. We present several improvements to the technique leading to increased reproducibility and accuracy. We designed a customised support system and used a combination of the commercially available Mercox II methyl methacrylate with the Batson's catalyst for optimal vascular Corrosion Casting of zebrafish. We also highlight different imaging approaches, with a focus on scanning electron microscopy (SEM) and X-ray microtomography (micro-CT) to obtain highly detailed, faithful three-dimensional reconstructed images of the zebrafish cardiovascular structure. This procedure can be of great value to a wide range of research lines related to cardiovascular biology in small specimens.
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Charlotte Debbaut Perfusion Characteristics of the Human Hepatic Microcirculation Based on Three-Dimensional Reconstructions and Computational Fluid Dynamic Analysis
2020Co-Authors: Jan Vierendeels, Pieter Cornillie, Denis Van Loo, Paul Simoens, Diethard Monbaliu, Van Luc, Patrick SegersAbstract:The perfusion of the liver microcirculation is often analyzed in terms of idealized functional units (hexagonal liver lobules) based on a porous medium approach. More elaborate research is essential to assess the validity of this approach and to provide a more adequate and quantitative characterization of the liver microcirculation. To this end, we modeled the perfusion of the liver microcirculation using an image-based three-dimensional (3D) reconstruction of human liver sinusoids and computational fluid dynamics techniques. After vascular Corrosion Casting, a microvascular sample (60.134 mm 3 ) representing three liver lobules, was dissected from a human liver vascular replica and scanned using a high resolution (2.6 lm) micro-CT scanner. Following image processing, a cube (0.15 Â 0.15 Â 0.15 mm 3 ) representing a sample of intertwined and interconnected sinusoids, was isolated from the 3D reconstructed dataset to define the fluid domain. Three models were studied to simulate flow along three orthogonal directions (i.e., parallel to the central vein and in the radial and circumferential directions of the lobule). Inflow and outflow guidances were added to facilitate solution convergence, and good quality volume meshes were obtained using approximately 9 Â 10 6 tetrahedral cells. Subsequently, three computational fluid dynamics models were generated and solved assuming Newtonian liquid properties (viscosity 3.5 mPa s). Post-processing allowed to visualize and quantify the microvascular flow characteristics, to calculate the permeability tensor and corresponding principal permeability axes, as well as the 3D porosity. The computational fluid dynamics simulations provided data on pressure differences, preferential flow pathways and wall shear stresses. Notably, the pressure difference resulting from the flow simulation parallel to the central vein (0-100 Pa) was clearly smaller than the difference from the radial (0-170 Pa) and circumferential (0-180 Pa) flow directions. This resulted in a higher permeability along the central vein direction (k d,33 ¼ 3.64 Â 10 À14 m 2 ) in comparison with the radial (k d,11 ¼ 1.56 Â 10 À14 m 2 ) and circumferential (k d,22 ¼ 1.75 Â 10 À14 m 2 ) permeabilities which were approximately equal. The mean 3D porosity was 14.3. Our data indicate that the human hepatic microcirculation is characterized by a higher permeability along the central vein direction, and an about two times lower permeability along the radial and circumferential directions of a lobule. Since the permeability coefficients depend on the flow direction, (porous medium) liver microcirculation models should take into account sinusoidal anisotropy
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analyzing the human liver vascular architecture by combining vascular Corrosion Casting and micro ct scanning a feasibility study
Journal of Anatomy, 2014Co-Authors: Charlotte Debbaut, Christophe Casteleyn, Pieter Cornillie, Patrick Segers, Manuel Dierick, Wim Laleman, Diethard MonbaliuAbstract:Although a full understanding of the hepatic circulation is one of the keys to successfully perform liver surgery and to elucidate liver pathology, relatively little is known about the functional organization of the liver vasculature. Therefore, we materialized and visualized the human hepatic vasculature at different scales, and performed a morphological analysis by combining vascular Corrosion Casting with novel micro-computer tomography (CT) and image analysis techniques. A human liver vascular Corrosion cast was obtained by simultaneous resin injection in the hepatic artery (HA) and portal vein (PV). A high resolution (110 μm) micro-CT scan of the total cast allowed gathering detailed macrovascular data. Subsequently, a mesocirculation sample (starting at generation 5; 88 × 68 × 80 mm³) and a microcirculation sample (terminal vessels including sinusoids; 2.0 × 1.5 × 1.7 mm³) were dissected and imaged at a 71-μm and 2.6-μm resolution, respectively. Segmentations and 3D reconstructions allowed quantifying the macro- and mesoscale branching topology, and geometrical features of HA, PV and hepatic venous trees up to 13 generations (radii ranging from 13.2 mm to 80 μm; lengths from 74.4 mm to 0.74 mm), as well as microvascular characteristics (mean sinusoidal radius of 6.63 μm). Combining Corrosion Casting and micro-CT imaging allows quantifying the branching topology and geometrical features of hepatic trees using a multiscale approach from the macro- down to the microcirculation. This may lead to novel insights into liver circulation, such as internal blood flow distributions and anatomical consequences of pathologies (e.g. cirrhosis).
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perfusion characteristics of the human hepatic microcirculation based on three dimensional reconstructions and computational fluid dynamic analysis
Journal of Biomechanical Engineering-transactions of The Asme, 2012Co-Authors: Charlotte Debbaut, Jan Vierendeels, Christophe Casteleyn, Pieter Cornillie, Denis Van Loo, Paul Simoens, Luc Van Hoorebeke, Diethard Monbaliu, Patrick SegersAbstract:The perfusion of the liver microcirculation is often analyzed in terms of idealized functional units (hexagonal liver lobules) based on a porous medium approach. More elaborate research is essential to assess the validity of this approach and to provide a more adequate and quantitative characterization of the liver microcirculation. To this end, we modeled the perfusion of the liver microcirculation using an image-based three-dimensional (3D) reconstruction of human liver sinusoids and computational fluid dynamics techniques. After vascular Corrosion Casting, a microvascular sample (+/-0.134 mm(3)) representing three liver lobules, was dissected from a human liver vascular replica and scanned using a high resolution (2.6 mu m) micro-CT scanner. Following image processing, a cube (0.15 x 0.15 x 0.15 mm(3)) representing a sample of intertwined and interconnected sinusoids, was isolated from the 3D reconstructed dataset to define the fluid domain. Three models were studied to simulate flow along three orthogonal directions (i.e., parallel to the central vein and in the radial and circumferential directions of the lobule). Inflow and outflow guidances were added to facilitate solution convergence, and good quality volume meshes were obtained using approximately 9 x 10(6) tetrahedral cells. Subsequently, three computational fluid dynamics models were generated and solved assuming Newtonian liquid properties (viscosity 3.5 mPa s). Post-processing allowed to visualize and quantify the microvascular flow characteristics, to calculate the permeability tensor and corresponding principal permeability axes, as well as the 3D porosity. The computational fluid dynamics simulations provided data on pressure differences, preferential flow pathways and wall shear stresses. Notably, the pressure difference resulting from the flow simulation parallel to the central vein (0-100 Pa) was clearly smaller than the difference from the radial (0-170 Pa) and circumferential (0-180 Pa) flow directions. This resulted in a higher permeability along the central vein direction (k(d,33) = 3.64 x 10(-14) m(2)) in comparison with the radial (k(d),(11) = 1.56 x 10(-14) m(2)) and circumferential (k(d,22) = 1.75 x 10(-14) m(2)) permeabilities which were approximately equal. The mean 3D porosity was 14.3. Our data indicate that the human hepatic microcirculation is characterized by a higher permeability along the central vein direction, and an about two times lower permeability along the radial and circumferential directions of a lobule. Since the permeability coefficients depend on the flow direction, (porous medium) liver microcirculation models should take into account sinusoidal anisotropy.
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multiscale modeling of the blood circulation in the human liver using vascular Corrosion Casting and micro ct imaging techniques
Proceedings of the ASME 2011 Summer Bioengineering Conference, 2011Co-Authors: Charlotte Debbaut, Christophe Casteleyn, Pieter Cornillie, Paul Simoens, Diethard Monbaliu, Jacques Pirenne, Luc Van Hoorebeke, Patrick SegersAbstract:Numerical models to analyze blood flow may be important for a better understanding of organ hemodynamics and (dys)function (e.g. in organ transplant research), and diagnostic techniques (e.g. contrast-enhanced MRI to characterize tumors). Existing models of (liver) vascular trees are predominantly based on idealized models using fractional calculus to describe bifurcating branching patterns. In contrast, we previously developed an electrical analog model of the human hepatic circulation, based on measured data of the macrocirculation and extrapolated data of the microcirculation [1]. Furthermore, the microcirculation is usually modeled as a porous medium [2].Copyright © 2011 by ASME
Christine E. Schmidt - One of the best experts on this subject based on the ideXlab platform.
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ultrasound guided photoacoustic imaging directed re endothelialization of acellular vasculature leads to improved vascular performance
Acta Biomaterialia, 2016Co-Authors: Ryan J Nagao, Yafei Ouyang, Renee Keller, George R Malik, Laura J Suggs, Stanislav Emelianov, Christine E. SchmidtAbstract:Abstract As increasing effort is dedicated to investigating the regenerative capacity of decellularized tissues, research has progressed to recellularizing these tissues prior to implantation. The delivery and support of cells seeded throughout acellular scaffolds are typically conducted through the vascular axis of the tissues. However, it is unclear how cell concentration and injection frequency can affect the distribution of cells throughout the scaffold. Furthermore, what effects re-endothelialization have on vascular patency and function are not well understood. We investigated the use of ultrasound-guided photoacoustic (US/PA) imaging as a technique to visualize the distribution of microvascular endothelial cells within an optimized acellular construct upon re-endothelialization and perfusion conditioning. We also evaluated the vascular performance of the re-endothelialized scaffold using quantitative vascular Corrosion Casting (qVCC) and whole-blood perfusion. We found US/PA imaging was an effective technique to visualize the distribution of cells. Cellular retention following perfusion conditioning was also detected with US/PA imaging. Finally, we demonstrated that a partial recovery of vascular performance is possible following re-endothelialization—confirmed by fewer extravasations in qVCC and improved blood clearance following whole-blood perfusion. Statement of Significance Re-endothelialization is a method that enables decellularized tissue to become useful as a tissue engineering construct by creating a nutrient delivery and waste removal system for the entire construct. Our approach utilizes a decellularization method that retains the basement ECM of a highly vascularized tissue upon which endothelial cells can be injected to form an endothelium. The US/PA method allows for rapid visualization of cells within a construct several cm thick. This approach can be experimentally used to observe changes in cellular distribution over large intervals of time, to help optimize cell seeding parameters, and to verify cell retention within re-endothelialized constructs. This approach has temporal and depth advantages compared to section reconstruction and imaged fluorophores respectively.
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ultrasound guided photoacoustic imaging directed re endothelialization of acellular vasculature leads to improved vascular performance
Acta Biomaterialia, 2016Co-Authors: Ryan J Nagao, Yafei Ouyang, Renee Keller, George R Malik, Laura J Suggs, Stanislav Emelianov, Christine E. SchmidtAbstract:Abstract As increasing effort is dedicated to investigating the regenerative capacity of decellularized tissues, research has progressed to recellularizing these tissues prior to implantation. The delivery and support of cells seeded throughout acellular scaffolds are typically conducted through the vascular axis of the tissues. However, it is unclear how cell concentration and injection frequency can affect the distribution of cells throughout the scaffold. Furthermore, what effects re-endothelialization have on vascular patency and function are not well understood. We investigated the use of ultrasound-guided photoacoustic (US/PA) imaging as a technique to visualize the distribution of microvascular endothelial cells within an optimized acellular construct upon re-endothelialization and perfusion conditioning. We also evaluated the vascular performance of the re-endothelialized scaffold using quantitative vascular Corrosion Casting (qVCC) and whole-blood perfusion. We found US/PA imaging was an effective technique to visualize the distribution of cells. Cellular retention following perfusion conditioning was also detected with US/PA imaging. Finally, we demonstrated that a partial recovery of vascular performance is possible following re-endothelialization—confirmed by fewer extravasations in qVCC and improved blood clearance following whole-blood perfusion. Statement of Significance Re-endothelialization is a method that enables decellularized tissue to become useful as a tissue engineering construct by creating a nutrient delivery and waste removal system for the entire construct. Our approach utilizes a decellularization method that retains the basement ECM of a highly vascularized tissue upon which endothelial cells can be injected to form an endothelium. The US/PA method allows for rapid visualization of cells within a construct several cm thick. This approach can be experimentally used to observe changes in cellular distribution over large intervals of time, to help optimize cell seeding parameters, and to verify cell retention within re-endothelialized constructs. This approach has temporal and depth advantages compared to section reconstruction and imaged fluorophores respectively.
Christophe Casteleyn - One of the best experts on this subject based on the ideXlab platform.
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Corrosion Casting in anatomy: Visualizing the architecture of hollow structures and surface details.
Anatomia Histologia Embryologia, 2019Co-Authors: Pieter Cornillie, Christophe Casteleyn, Christoph Von Horst, Robert W. HenryAbstract:Corrosion Casting is the technique by which a solid, negative replica is created from a hollow anatomical structure and liberated from its surrounding tissues. For centuries, different types of hardening substances have been developed to create such casts, but nowadays, thermosetting polymers are mostly used as Casting medium. Although the principle and initial set-up are relatively easy, producing high-quality casts that serve their intended purpose can be quite challenging. This paper evaluates some of the more popular Casting resins that are currently available and provides a step-by-step overview of the Corrosion Casting procedure, including surface casts of anatomical structures. Hurdles and pitfalls are discussed, along with possible solutions to circumvent them, based on personal experience by the authors.
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analyzing the human liver vascular architecture by combining vascular Corrosion Casting and micro ct scanning a feasibility study
Journal of Anatomy, 2014Co-Authors: Charlotte Debbaut, Christophe Casteleyn, Pieter Cornillie, Patrick Segers, Manuel Dierick, Wim Laleman, Diethard MonbaliuAbstract:Although a full understanding of the hepatic circulation is one of the keys to successfully perform liver surgery and to elucidate liver pathology, relatively little is known about the functional organization of the liver vasculature. Therefore, we materialized and visualized the human hepatic vasculature at different scales, and performed a morphological analysis by combining vascular Corrosion Casting with novel micro-computer tomography (CT) and image analysis techniques. A human liver vascular Corrosion cast was obtained by simultaneous resin injection in the hepatic artery (HA) and portal vein (PV). A high resolution (110 μm) micro-CT scan of the total cast allowed gathering detailed macrovascular data. Subsequently, a mesocirculation sample (starting at generation 5; 88 × 68 × 80 mm³) and a microcirculation sample (terminal vessels including sinusoids; 2.0 × 1.5 × 1.7 mm³) were dissected and imaged at a 71-μm and 2.6-μm resolution, respectively. Segmentations and 3D reconstructions allowed quantifying the macro- and mesoscale branching topology, and geometrical features of HA, PV and hepatic venous trees up to 13 generations (radii ranging from 13.2 mm to 80 μm; lengths from 74.4 mm to 0.74 mm), as well as microvascular characteristics (mean sinusoidal radius of 6.63 μm). Combining Corrosion Casting and micro-CT imaging allows quantifying the branching topology and geometrical features of hepatic trees using a multiscale approach from the macro- down to the microcirculation. This may lead to novel insights into liver circulation, such as internal blood flow distributions and anatomical consequences of pathologies (e.g. cirrhosis).
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perfusion characteristics of the human hepatic microcirculation based on three dimensional reconstructions and computational fluid dynamic analysis
Journal of Biomechanical Engineering-transactions of The Asme, 2012Co-Authors: Charlotte Debbaut, Jan Vierendeels, Christophe Casteleyn, Pieter Cornillie, Denis Van Loo, Paul Simoens, Luc Van Hoorebeke, Diethard Monbaliu, Patrick SegersAbstract:The perfusion of the liver microcirculation is often analyzed in terms of idealized functional units (hexagonal liver lobules) based on a porous medium approach. More elaborate research is essential to assess the validity of this approach and to provide a more adequate and quantitative characterization of the liver microcirculation. To this end, we modeled the perfusion of the liver microcirculation using an image-based three-dimensional (3D) reconstruction of human liver sinusoids and computational fluid dynamics techniques. After vascular Corrosion Casting, a microvascular sample (+/-0.134 mm(3)) representing three liver lobules, was dissected from a human liver vascular replica and scanned using a high resolution (2.6 mu m) micro-CT scanner. Following image processing, a cube (0.15 x 0.15 x 0.15 mm(3)) representing a sample of intertwined and interconnected sinusoids, was isolated from the 3D reconstructed dataset to define the fluid domain. Three models were studied to simulate flow along three orthogonal directions (i.e., parallel to the central vein and in the radial and circumferential directions of the lobule). Inflow and outflow guidances were added to facilitate solution convergence, and good quality volume meshes were obtained using approximately 9 x 10(6) tetrahedral cells. Subsequently, three computational fluid dynamics models were generated and solved assuming Newtonian liquid properties (viscosity 3.5 mPa s). Post-processing allowed to visualize and quantify the microvascular flow characteristics, to calculate the permeability tensor and corresponding principal permeability axes, as well as the 3D porosity. The computational fluid dynamics simulations provided data on pressure differences, preferential flow pathways and wall shear stresses. Notably, the pressure difference resulting from the flow simulation parallel to the central vein (0-100 Pa) was clearly smaller than the difference from the radial (0-170 Pa) and circumferential (0-180 Pa) flow directions. This resulted in a higher permeability along the central vein direction (k(d,33) = 3.64 x 10(-14) m(2)) in comparison with the radial (k(d),(11) = 1.56 x 10(-14) m(2)) and circumferential (k(d,22) = 1.75 x 10(-14) m(2)) permeabilities which were approximately equal. The mean 3D porosity was 14.3. Our data indicate that the human hepatic microcirculation is characterized by a higher permeability along the central vein direction, and an about two times lower permeability along the radial and circumferential directions of a lobule. Since the permeability coefficients depend on the flow direction, (porous medium) liver microcirculation models should take into account sinusoidal anisotropy.
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multiscale modeling of the blood circulation in the human liver using vascular Corrosion Casting and micro ct imaging techniques
Proceedings of the ASME 2011 Summer Bioengineering Conference, 2011Co-Authors: Charlotte Debbaut, Christophe Casteleyn, Pieter Cornillie, Paul Simoens, Diethard Monbaliu, Jacques Pirenne, Luc Van Hoorebeke, Patrick SegersAbstract:Numerical models to analyze blood flow may be important for a better understanding of organ hemodynamics and (dys)function (e.g. in organ transplant research), and diagnostic techniques (e.g. contrast-enhanced MRI to characterize tumors). Existing models of (liver) vascular trees are predominantly based on idealized models using fractional calculus to describe bifurcating branching patterns. In contrast, we previously developed an electrical analog model of the human hepatic circulation, based on measured data of the macrocirculation and extrapolated data of the microcirculation [1]. Furthermore, the microcirculation is usually modeled as a porous medium [2].Copyright © 2011 by ASME
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replacing vascular Corrosion Casting by in vivo micro ct imaging for building 3d cardiovascular models in mice
Molecular Imaging and Biology, 2011Co-Authors: Bert Vandeghinste, Christophe Casteleyn, Patrick Segers, Bram Trachet, Marjolijn Renard, Steven Staelens, Bart Loeys, Stefaan VandenbergheAbstract:The purpose of this study was to investigate if in vivo micro-computed tomography (CT) is a reliable alternative to micro-CT scanning of a vascular Corrosion cast. This would allow one to study the early development of cardiovascular diseases. Datasets using both modalities were acquired, segmented, and used to generate a 3D geometrical model from nine mice. As blood pool contrast agent, Fenestra VC-131 was used. Batson’s No. 17 was used as Casting agent. Computational fluid dynamics simulations were performed on both datasets to quantify the difference in wall shear stress (WSS). Aortic arch diameters show 30% to 40% difference between the Fenestra VC-131 and the casted dataset. The aortic arch bifurcation angles show less than 20% difference between both datasets. Numerically computed WSS showed a 28% difference between both datasets. Our results indicate that in vivo micro-CT imaging can provide an excellent alternative for vascular Corrosion Casting. This enables follow-up studies.
A J Miodonski - One of the best experts on this subject based on the ideXlab platform.
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arterial supply and venous drainage of the choroid plexus of the human lateral ventricle in the prenatal period as revealed by vascular Corrosion casts and sem
Folia Morphologica, 2008Co-Authors: K Zagorskaswiezy, J Gorczyca, J A Litwin, Kazimierz Pitynski, A J MiodonskiAbstract:The topography of the arterial supply and venous drainage was visualised by Corrosion Casting and scanning electron microscopy in the human foetal (20 weeks) choroid plexus of the lateral ventricle. Although secondary villi were not yet present at that developmental stage, the topography of the large arteries and veins almost fully corresponded to that described in adult individuals. The only major difference observed was a lack of the typical tortuosity of the lateral branch of the anterior choroidal artery and of the superior choroidal vein, which probably develops during further expansion of the vascular system associated with the formation of secondary villi.
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the microvascular architecture of the choroid plexus in fetal human brain lateral ventricle a scanning electron microscopy study of Corrosion casts
Journal of Anatomy, 2008Co-Authors: K Zagorskaswiezy, J Gorczyca, J A Litwin, Kazimierz Pitynski, A J MiodonskiAbstract:The microvascular architecture of developing lateral ventricle choroid plexus was investigated by Corrosion Casting and scanning electron microscopy in human fetuses aged 20 gestational weeks. The areas with different microvascular patterns corresponded to the particular parts of the mature plexus: anterior part, glomus, posterior part, the villous fringe and the free margin. In the posterior part, densely packed parallel arterioles and venules were surrounded by sheath-like capillary networks. Other areas contained compact capillary plexuses of the primary villi: the most prominent, protruding basket- and leaf-shaped plexuses were observed in the villous fringe, whilst less numerous and smaller plexuses occurred in the anterior part and glomus. The capillaries of the plexuses had a large diameter and sinusoidal dilations, and showed the presence of occasional short, blind sprouts indicative of angiogenesis. Short anastomoses between arterioles supplying the plexuses and venules draining them were only rarely observed. In the upper area of the choroid plexus, the superior choroidal vein was surrounded by a capillary network forming small, glomerular or rosette-shapes plexuses. The free margin of the choroid plexus was characterized by flat, multiple, arcade-like capillary loops. The general vascular architecture of the human choroid plexus at 20 gestational weeks seems to be similar to that of postnatal/mature plexus, still lacking, however, the complex vascular plexuses of the secondary villi.
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vascular system of intramural leiomyomata revealed by Corrosion Casting and scanning electron microscopy
Human Reproduction, 2003Co-Authors: Jerzy A Walocha, Jan A Litwin, A J MiodonskiAbstract:BACKGROUND: The vascular system of leiomyomata, the most common benign tumours in women, is an important factor controlling development and growth of the tumour. It has not been, however, investigated morphologically using the best currently available technique, Corrosion Casting combined with scanning electron microscopy. METHODS: Myomatous uteri collected upon autopsy were perfused via afferent vessels with fixative followed by Mercox resin and corroded after polymerization of the resin. The obtained vascular casts visualizing all vessels including capillaries were examined using scanning electron microscopy. RESULTS: The smallest (1‐3 mm) fibroids were avascular, in larger ones ( 1 cm) contained irregular networks of blood vessels with density similar to or lower than that of normal myometrium. Such tumours were surrounded by an extremely dense vascular layer (‘vascular capsule’) which was the source of larger vessels supplying and draining the tumour. CONCLUSIONS: During development of leiomyoma, the pre-existing blood vessels undergo regression and new vessels invade the tumour from the periphery, where intense angiogenesis, probably promoted by growth factors secreted by the tumour, leads to the formation of a ‘vascular capsule’ responsible for supply of blood to the growing tumour.
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microvascular Corrosion Casting in the study of tumor vascularity a review
Scanning microscopy, 1995Co-Authors: M A Konerding, A J Miodonski, Alois LametschwandtnerAbstract:Tumor blood flow is dependent on the structure and three-dimensional (3-D) architecture of the vascular network. The latter can be best studied by scanning electron microscopy of microvascular Corrosion casts. However, literature reviews show that nearly all studies using this technique render comparisons of different tumors more difficult since they are mainly based on descriptive terms that might lead to misunderstandings. Qualitative comparisons of 13 experimental and 3 human primary tumors of different origin show a high degree of similarity in the vasculature. Quantitative analysis of these casts reveals similar ranges of parameters such as diameters, intervascular and interbranching distances. Diameters of vessels with capillary wall structure range from 6 micron m to 55 micron m in the human primary tumors (renal clear cell carcinoma, basalioma), and from 5 micron m to 80 micron m in xenografted tumors (sarcomas, colon carcinoma). Intervascular distances in the human primary tumors range from 2 micron m to 52 micron m, and from 11 micron m to 105 micron m in the xenografts. Interbranching distances range from 34 micron m to 258 micron m in the former, and from 11 micron m to 160 micron m in the latter. Both qualitative and quantitative analyses of tumor microvascular Corrosion casts enable pathophysiological conclusions to be drawn and contribute to a better understanding of tumor vascularity.
Pieter Cornillie - One of the best experts on this subject based on the ideXlab platform.
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Charlotte Debbaut Perfusion Characteristics of the Human Hepatic Microcirculation Based on Three-Dimensional Reconstructions and Computational Fluid Dynamic Analysis
2020Co-Authors: Jan Vierendeels, Pieter Cornillie, Denis Van Loo, Paul Simoens, Diethard Monbaliu, Van Luc, Patrick SegersAbstract:The perfusion of the liver microcirculation is often analyzed in terms of idealized functional units (hexagonal liver lobules) based on a porous medium approach. More elaborate research is essential to assess the validity of this approach and to provide a more adequate and quantitative characterization of the liver microcirculation. To this end, we modeled the perfusion of the liver microcirculation using an image-based three-dimensional (3D) reconstruction of human liver sinusoids and computational fluid dynamics techniques. After vascular Corrosion Casting, a microvascular sample (60.134 mm 3 ) representing three liver lobules, was dissected from a human liver vascular replica and scanned using a high resolution (2.6 lm) micro-CT scanner. Following image processing, a cube (0.15 Â 0.15 Â 0.15 mm 3 ) representing a sample of intertwined and interconnected sinusoids, was isolated from the 3D reconstructed dataset to define the fluid domain. Three models were studied to simulate flow along three orthogonal directions (i.e., parallel to the central vein and in the radial and circumferential directions of the lobule). Inflow and outflow guidances were added to facilitate solution convergence, and good quality volume meshes were obtained using approximately 9 Â 10 6 tetrahedral cells. Subsequently, three computational fluid dynamics models were generated and solved assuming Newtonian liquid properties (viscosity 3.5 mPa s). Post-processing allowed to visualize and quantify the microvascular flow characteristics, to calculate the permeability tensor and corresponding principal permeability axes, as well as the 3D porosity. The computational fluid dynamics simulations provided data on pressure differences, preferential flow pathways and wall shear stresses. Notably, the pressure difference resulting from the flow simulation parallel to the central vein (0-100 Pa) was clearly smaller than the difference from the radial (0-170 Pa) and circumferential (0-180 Pa) flow directions. This resulted in a higher permeability along the central vein direction (k d,33 ¼ 3.64 Â 10 À14 m 2 ) in comparison with the radial (k d,11 ¼ 1.56 Â 10 À14 m 2 ) and circumferential (k d,22 ¼ 1.75 Â 10 À14 m 2 ) permeabilities which were approximately equal. The mean 3D porosity was 14.3. Our data indicate that the human hepatic microcirculation is characterized by a higher permeability along the central vein direction, and an about two times lower permeability along the radial and circumferential directions of a lobule. Since the permeability coefficients depend on the flow direction, (porous medium) liver microcirculation models should take into account sinusoidal anisotropy
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Corrosion Casting in anatomy: Visualizing the architecture of hollow structures and surface details.
Anatomia Histologia Embryologia, 2019Co-Authors: Pieter Cornillie, Christophe Casteleyn, Christoph Von Horst, Robert W. HenryAbstract:Corrosion Casting is the technique by which a solid, negative replica is created from a hollow anatomical structure and liberated from its surrounding tissues. For centuries, different types of hardening substances have been developed to create such casts, but nowadays, thermosetting polymers are mostly used as Casting medium. Although the principle and initial set-up are relatively easy, producing high-quality casts that serve their intended purpose can be quite challenging. This paper evaluates some of the more popular Casting resins that are currently available and provides a step-by-step overview of the Corrosion Casting procedure, including surface casts of anatomical structures. Hurdles and pitfalls are discussed, along with possible solutions to circumvent them, based on personal experience by the authors.
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analyzing the human liver vascular architecture by combining vascular Corrosion Casting and micro ct scanning a feasibility study
Journal of Anatomy, 2014Co-Authors: Charlotte Debbaut, Christophe Casteleyn, Pieter Cornillie, Patrick Segers, Manuel Dierick, Wim Laleman, Diethard MonbaliuAbstract:Although a full understanding of the hepatic circulation is one of the keys to successfully perform liver surgery and to elucidate liver pathology, relatively little is known about the functional organization of the liver vasculature. Therefore, we materialized and visualized the human hepatic vasculature at different scales, and performed a morphological analysis by combining vascular Corrosion Casting with novel micro-computer tomography (CT) and image analysis techniques. A human liver vascular Corrosion cast was obtained by simultaneous resin injection in the hepatic artery (HA) and portal vein (PV). A high resolution (110 μm) micro-CT scan of the total cast allowed gathering detailed macrovascular data. Subsequently, a mesocirculation sample (starting at generation 5; 88 × 68 × 80 mm³) and a microcirculation sample (terminal vessels including sinusoids; 2.0 × 1.5 × 1.7 mm³) were dissected and imaged at a 71-μm and 2.6-μm resolution, respectively. Segmentations and 3D reconstructions allowed quantifying the macro- and mesoscale branching topology, and geometrical features of HA, PV and hepatic venous trees up to 13 generations (radii ranging from 13.2 mm to 80 μm; lengths from 74.4 mm to 0.74 mm), as well as microvascular characteristics (mean sinusoidal radius of 6.63 μm). Combining Corrosion Casting and micro-CT imaging allows quantifying the branching topology and geometrical features of hepatic trees using a multiscale approach from the macro- down to the microcirculation. This may lead to novel insights into liver circulation, such as internal blood flow distributions and anatomical consequences of pathologies (e.g. cirrhosis).
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perfusion characteristics of the human hepatic microcirculation based on three dimensional reconstructions and computational fluid dynamic analysis
Journal of Biomechanical Engineering-transactions of The Asme, 2012Co-Authors: Charlotte Debbaut, Jan Vierendeels, Christophe Casteleyn, Pieter Cornillie, Denis Van Loo, Paul Simoens, Luc Van Hoorebeke, Diethard Monbaliu, Patrick SegersAbstract:The perfusion of the liver microcirculation is often analyzed in terms of idealized functional units (hexagonal liver lobules) based on a porous medium approach. More elaborate research is essential to assess the validity of this approach and to provide a more adequate and quantitative characterization of the liver microcirculation. To this end, we modeled the perfusion of the liver microcirculation using an image-based three-dimensional (3D) reconstruction of human liver sinusoids and computational fluid dynamics techniques. After vascular Corrosion Casting, a microvascular sample (+/-0.134 mm(3)) representing three liver lobules, was dissected from a human liver vascular replica and scanned using a high resolution (2.6 mu m) micro-CT scanner. Following image processing, a cube (0.15 x 0.15 x 0.15 mm(3)) representing a sample of intertwined and interconnected sinusoids, was isolated from the 3D reconstructed dataset to define the fluid domain. Three models were studied to simulate flow along three orthogonal directions (i.e., parallel to the central vein and in the radial and circumferential directions of the lobule). Inflow and outflow guidances were added to facilitate solution convergence, and good quality volume meshes were obtained using approximately 9 x 10(6) tetrahedral cells. Subsequently, three computational fluid dynamics models were generated and solved assuming Newtonian liquid properties (viscosity 3.5 mPa s). Post-processing allowed to visualize and quantify the microvascular flow characteristics, to calculate the permeability tensor and corresponding principal permeability axes, as well as the 3D porosity. The computational fluid dynamics simulations provided data on pressure differences, preferential flow pathways and wall shear stresses. Notably, the pressure difference resulting from the flow simulation parallel to the central vein (0-100 Pa) was clearly smaller than the difference from the radial (0-170 Pa) and circumferential (0-180 Pa) flow directions. This resulted in a higher permeability along the central vein direction (k(d,33) = 3.64 x 10(-14) m(2)) in comparison with the radial (k(d),(11) = 1.56 x 10(-14) m(2)) and circumferential (k(d,22) = 1.75 x 10(-14) m(2)) permeabilities which were approximately equal. The mean 3D porosity was 14.3. Our data indicate that the human hepatic microcirculation is characterized by a higher permeability along the central vein direction, and an about two times lower permeability along the radial and circumferential directions of a lobule. Since the permeability coefficients depend on the flow direction, (porous medium) liver microcirculation models should take into account sinusoidal anisotropy.
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multiscale modeling of the blood circulation in the human liver using vascular Corrosion Casting and micro ct imaging techniques
Proceedings of the ASME 2011 Summer Bioengineering Conference, 2011Co-Authors: Charlotte Debbaut, Christophe Casteleyn, Pieter Cornillie, Paul Simoens, Diethard Monbaliu, Jacques Pirenne, Luc Van Hoorebeke, Patrick SegersAbstract:Numerical models to analyze blood flow may be important for a better understanding of organ hemodynamics and (dys)function (e.g. in organ transplant research), and diagnostic techniques (e.g. contrast-enhanced MRI to characterize tumors). Existing models of (liver) vascular trees are predominantly based on idealized models using fractional calculus to describe bifurcating branching patterns. In contrast, we previously developed an electrical analog model of the human hepatic circulation, based on measured data of the macrocirculation and extrapolated data of the microcirculation [1]. Furthermore, the microcirculation is usually modeled as a porous medium [2].Copyright © 2011 by ASME
