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Kopylova V, Boronovskiy S, Nartsissov Y. Approaches to vascular network, blood flow, and metabolite distribution modeling in brain tissue. Biophys Rev 2023; 15:1335-1350. [PMID: 37974995 PMCID: PMC10643724 DOI: 10.1007/s12551-023-01106-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 07/24/2023] [Indexed: 11/19/2023] Open
Abstract
The cardiovascular system plays a key role in the transport of nutrients, ensuring a continuous supply of all cells of the body with the metabolites necessary for life. The blood supply to the brain is carried out by the large arteries located on its surface, which branch into smaller arterioles that penetrate the cerebral cortex and feed the capillary bed, thereby forming an extensive branching network. The formation of blood vessels is carried out via vasculogenesis and angiogenesis, which play an important role in both embryo and adult life. The review presents approaches to modeling various aspects of both the formation of vascular networks and the construction of the formed arterial tree. In addition, a brief description of models that allows one to study the blood flow in various parts of the circulatory system and the spatiotemporal metabolite distribution in brain tissues is given. Experimental study of these issues is not always possible due to both the complexity of the cardiovascular system and the mechanisms through which the perfusion of all body cells is carried out. In this regard, mathematical models are a good tool for studying hemodynamics and can be used in clinical practice to diagnose vascular diseases and assess the need for treatment.
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Affiliation(s)
- Veronika Kopylova
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404 Russia
| | | | - Yaroslav Nartsissov
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404 Russia
- Biomedical Research Group, BiDiPharma GmbH, Siek, 22962 Germany
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2
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Whitehead JF, Laeseke PF, Periyasamy S, Speidel MA, Wagner MG. In silico simulation of hepatic arteries: An open-source algorithm for efficient synthetic data generation. Med Phys 2023; 50:5505-5517. [PMID: 36950870 PMCID: PMC10517083 DOI: 10.1002/mp.16379] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 02/28/2023] [Accepted: 03/13/2023] [Indexed: 03/24/2023] Open
Abstract
BACKGROUND In silico testing of novel image reconstruction and quantitative algorithms designed for interventional imaging requires realistic high-resolution modeling of arterial trees with contrast dynamics. Furthermore, data synthesis for training of deep learning algorithms requires that an arterial tree generation algorithm be computationally efficient and sufficiently random. PURPOSE The purpose of this paper is to provide a method for anatomically and physiologically motivated, computationally efficient, random hepatic arterial tree generation. METHODS The vessel generation algorithm uses a constrained constructive optimization approach with a volume minimization-based cost function. The optimization is constrained by the Couinaud liver classification system to assure a main feeding artery to each Couinaud segment. An intersection check is included to guarantee non-intersecting vasculature and cubic polynomial fits are used to optimize bifurcation angles and to generate smoothly curved segments. Furthermore, an approach to simulate contrast dynamics and respiratory and cardiac motion is also presented. RESULTS The proposed algorithm can generate a synthetic hepatic arterial tree with 40 000 branches in 11 s. The high-resolution arterial trees have realistic morphological features such as branching angles (MAD with Murray's law= 1.2 ± 1 . 2 o $ = \;1.2 \pm {1.2^o}$ ), radii (median Murray deviation= 0.08 $ = \;0.08$ ), and smoothly curved, non-intersecting vessels. Furthermore, the algorithm assures a main feeding artery to each Couinaud segment and is random (variability = 0.98 ± 0.01). CONCLUSIONS This method facilitates the generation of large datasets of high-resolution, unique hepatic angiograms for the training of deep learning algorithms and initial testing of novel 3D reconstruction and quantitative algorithms designed for interventional imaging.
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Affiliation(s)
- Joseph F. Whitehead
- Department of Medical Physics, University of Wisconsin – Madison, Madison, WI 53705, USA
| | - Paul F. Laeseke
- Department of Radiology, University of Wisconsin – Madison, Madison, WI 53792, USA
| | - Sarvesh Periyasamy
- Department of Radiology, University of Wisconsin – Madison, Madison, WI 53792, USA
| | - Michael A. Speidel
- Department of Medical Physics, University of Wisconsin – Madison, Madison, WI 53705, USA
- Department of Medicine, University of Wisconsin – Madison, Madison WI 53705, USA
| | - Martin G. Wagner
- Department of Medical Physics, University of Wisconsin – Madison, Madison, WI 53705, USA
- Department of Radiology, University of Wisconsin – Madison, Madison, WI 53792, USA
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3
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Ho H, Means S, Safaei S, Hunter PJ. In silico modeling for the hepatic circulation and transport: From the liver organ to lobules. WIREs Mech Dis 2023; 15:e1586. [PMID: 36131627 DOI: 10.1002/wsbm.1586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 08/08/2022] [Accepted: 08/15/2022] [Indexed: 11/12/2022]
Abstract
The function of the liver depends critically on its blood supply. Numerous in silico models have been developed to study various aspects of the hepatic circulation, including not only the macro-hemodynamics at the organ level, but also the microcirculation at the lobular level. In addition, computational models of blood flow and bile flow have been used to study the transport, metabolism, and clearance of drugs in pharmacokinetic studies. These in silico models aim to provide insights into the liver organ function under both healthy and diseased states, and to assist quantitative analysis for surgical planning and postsurgery treatment. The purpose of this review is to provide an update on state-of-the-art in silico models of the hepatic circulation and transport processes. We introduce the numerical methods and the physiological background of these models. We also discuss multiscale frameworks that have been proposed for the liver, and their linkage with the large context of systems biology, systems pharmacology, and the Physiome project. This article is categorized under: Metabolic Diseases > Computational Models Metabolic Diseases > Biomedical Engineering Cardiovascular Diseases > Computational Models.
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Affiliation(s)
- Harvey Ho
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Shawn Means
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Soroush Safaei
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Peter John Hunter
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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Jessen E, Steinbach MC, Debbaut C, Schillinger D. Rigorous mathematical optimization of synthetic hepatic vascular trees. J R Soc Interface 2022; 19:20220087. [PMID: 35702863 PMCID: PMC9198513 DOI: 10.1098/rsif.2022.0087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In this paper, we introduce a new framework for generating synthetic vascular trees, based on rigorous model-based mathematical optimization. Our main contribution is the reformulation of finding the optimal global tree geometry into a nonlinear optimization problem (NLP). This rigorous mathematical formulation accommodates efficient solution algorithms such as the interior point method and allows us to easily change boundary conditions and constraints applied to the tree. Moreover, it creates trifurcations in addition to bifurcations. A second contribution is the addition of an optimization stage for the tree topology. Here, we combine constrained constructive optimization (CCO) with a heuristic approach to search among possible tree topologies. We combine the NLP formulation and the topology optimization into a single algorithmic approach. Finally, we attempt the validation of our new model-based optimization framework using a detailed corrosion cast of a human liver, which allows a quantitative comparison of the synthetic tree structure with the tree structure determined experimentally down to the fifth generation. The results show that our new framework is capable of generating asymmetric synthetic trees that match the available physiological corrosion cast data better than trees generated by the standard CCO approach.
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Affiliation(s)
- Etienne Jessen
- Institute of Mechanics, Computational Mechanics Group, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Marc C Steinbach
- Institute of Applied Mathematics, Leibniz Universität Hannover, 30167 Hannover, Germany
| | | | - Dominik Schillinger
- Institute of Mechanics, Computational Mechanics Group, Technical University of Darmstadt, 64287 Darmstadt, Germany
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Techniques and Algorithms for Hepatic Vessel Skeletonization in Medical Images: A Survey. ENTROPY 2022; 24:e24040465. [PMID: 35455128 PMCID: PMC9031516 DOI: 10.3390/e24040465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/21/2022] [Accepted: 03/23/2022] [Indexed: 02/01/2023]
Abstract
Hepatic vessel skeletonization serves as an important means of hepatic vascular analysis and vessel segmentation. This paper presents a survey of techniques and algorithms for hepatic vessel skeletonization in medical images. We summarized the latest developments and classical approaches in this field. These methods are classified into five categories according to their methodological characteristics. The overview and brief assessment of each category are provided in the corresponding chapters, respectively. We provide a comprehensive summary among the cited publications, image modalities and datasets from various aspects, which hope to reveal the pros and cons of every method, summarize its achievements and discuss the challenges and future trends.
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Taibbi G, Young M, Vyas RJ, Murray MC, Lim S, Predovic M, Jacobs NM, Askin KN, Mason SS, Zanello SB, Vizzeri G, Theriot CA, Parsons-Wingerter P. Opposite response of blood vessels in the retina to 6° head-down tilt and long-duration microgravity. NPJ Microgravity 2021; 7:38. [PMID: 34650071 PMCID: PMC8516890 DOI: 10.1038/s41526-021-00165-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 08/19/2021] [Indexed: 01/13/2023] Open
Abstract
The Spaceflight Associated Neuro-ocular Syndrome (SANS), associated with the headward fluid shifts incurred in microgravity during long-duration missions, remains a high-priority health and performance risk for human space exploration. To help characterize the pathophysiology of SANS, NASA's VESsel GENeration Analysis (VESGEN) software was used to map and quantify vascular adaptations in the retina before and after 70 days of bed rest at 6-degree Head-Down Tilt (HDT), a well-studied microgravity analog. Results were compared to the retinal vascular response of astronauts following 6-month missions to the International Space Station (ISS). By mixed effects modeling, the trends of vascular response were opposite. Vascular density decreased significantly in the 16 retinas of eight astronauts and in contrast, increased slightly in the ten retinas of five subjects after HDT (although with limited significance). The one astronaut retina diagnosed with SANS displayed the greatest vascular loss. Results suggest that microgravity is a major variable in the retinal mediation of fluid shifts that is not reproduced in this HDT bed rest model.
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Affiliation(s)
- Giovanni Taibbi
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | | | - Ruchi J Vyas
- Mori Associates, Ames Research Center, NASA, Moffett Field, Mountain View, CA, USA
| | - Matthew C Murray
- Blue Marble Space Institute of Science, Space Biology Division, Space Technology Mission Directorate, Ames Research Center, NASA, Moffett Field, Mountain View, CA, USA
| | - Shiyin Lim
- Blue Marble Space Institute of Science, Space Biology Division, Space Technology Mission Directorate, Ames Research Center, NASA, Moffett Field, Mountain View, CA, USA
| | - Marina Predovic
- Blue Marble Space Institute of Science, Space Biology Division, Space Technology Mission Directorate, Ames Research Center, NASA, Moffett Field, Mountain View, CA, USA
| | - Nicole M Jacobs
- Blue Marble Space Institute of Science, Space Biology Division, Space Technology Mission Directorate, Ames Research Center, NASA, Moffett Field, Mountain View, CA, USA
| | - Kayleigh N Askin
- National Space Biomedical Research Institute, Ames Research Center, NASA, Moffett Field, Mountain View, CA, USA
| | | | | | - Gianmarco Vizzeri
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Corey A Theriot
- KBR, NASA Johnson Space Center, Houston, TX, USA
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, TX, USA
| | - Patricia Parsons-Wingerter
- Low Gravity Exploration Technology, Research and Engineering Directorate, John Glenn Research Center, NASA, Cleveland, OH, USA.
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Nazir A, Cheema MN, Sheng B, Li P, Kim J, Lee TY. Living Donor-Recipient Pair Matching for Liver Transplant via Ternary Tree Representation With Cascade Incremental Learning. IEEE Trans Biomed Eng 2021; 68:2540-2551. [PMID: 33417536 DOI: 10.1109/tbme.2021.3050310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Visual understanding of liver vessels anatomy between the living donor-recipient (LDR) pair can assist surgeons to optimize transplant planning by avoiding non-targeted arteries which can cause severe complications. We propose to visually analyze the anatomical variants of the liver vessels anatomy to maximize similarity for finding a suitable Living Donor-Recipient (LDR) pair. Liver vessels are segmented from computed tomography angiography (CTA) volumes by employing a cascade incremental learning (CIL) model. Our CIL architecture is able to find optimal solutions, which we use to update the model with liver vessel CTA images. A novel ternary tree based algorithm is proposed to map all the possible liver vessel variants into their respective tree topologies. The tree topologies of the recipient's and donor's liver vessels are then used for an appropriate matching. The proposed algorithm utilizes a set of defined vessel tree variants which are updated to maintain the maximum matching options by leveraging the accurate segmentation results of the vessels derived from the incremental learning ability of the CIL. We introduce a novel concept of in-order digital string based comparison to match the geometry of two anatomically varied trees. Experiments through visual illustrations and quantitative analysis demonstrated the effectiveness of our approach compared to state-of-the-art.
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Vyas RJ, Young M, Murray MC, Predovic M, Lim S, Jacobs NM, Mason SS, Zanello SB, Taibbi G, Vizzeri G, Parsons-Wingerter P. Decreased Vascular Patterning in the Retinas of Astronaut Crew Members as New Measure of Ocular Damage in Spaceflight-Associated Neuro-ocular Syndrome. Invest Ophthalmol Vis Sci 2020; 61:34. [PMID: 33372980 PMCID: PMC7774106 DOI: 10.1167/iovs.61.14.34] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 11/11/2020] [Indexed: 02/04/2023] Open
Abstract
Purpose Ocular structural and functional changes, collectively termed spaceflight-associated neuro-ocular syndrome (SANS), have been described in astronauts undergoing long-duration missions in the microgravity environment of the International Space Station. We tested the hypothesis that retinal vascular remodeling, particularly by smaller vessels, mediates the chronic headward fluid shifts associated with SANS. Methods As a retrospective study, arterial and venous patterns extracted from 30° infrared Heidelberg Spectralis retinal images of eight crew members acquired before and after six-month missions were analyzed with NASA's recently released VESsel GENeration Analysis (VESGEN) software. Output parameters included the fractal dimension and overall vessel length density that was further classified into large and small vascular branching generations. Vascular results were compared with SANS-associated clinical ocular measures. Results Significant postflight decreases in Df, Lv, and in smaller but not larger vessels were quantified in 11 of 16 retinas for arteries and veins (P value for Df, Lv, and smaller vessels in all 16 retinas were ≤0.033). The greatest vascular decreases occurred in the only retina displaying clinical evidence of SANS by choroidal folds and optic disc edema. In the remaining 15 retinas, decreases in vascular density from Df and Lv ranged from minimal to high by a custom Subclinical Vascular Pathology Index. Conclusions Together with VESGEN, the Subclinical Vascular Pathology Index may represent a new, useful SANS biomarker for advancing the understanding of SANS etiology and developing successful countermeasures for long duration space exploration in microgravity, although further research is required to better characterize retinal microvascular adaptations.
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Affiliation(s)
- Ruchi J. Vyas
- SGT Incorporated, NASA Ames Research Center, Mountain View, California, United States
| | | | - Matthew C. Murray
- Ames Blue Marble Space Institute of Science, NASA Ames Research Center, Mountain View, California, United States
| | - Marina Predovic
- Ames Blue Marble Space Institute of Science, NASA Ames Research Center, Mountain View, California, United States
| | - Shiyin Lim
- Ames Blue Marble Space Institute of Science, NASA Ames Research Center, Mountain View, California, United States
| | - Nicole M. Jacobs
- Ames Blue Marble Space Institute of Science, NASA Ames Research Center, Mountain View, California, United States
| | - Sara S. Mason
- MEI Technologies, NASA Johnson Space Center, Houston, Texas, United States
| | | | - Giovanni Taibbi
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
| | - Gianmarco Vizzeri
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
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Liver Bioreactor Design Issues of Fluid Flow and Zonation, Fibrosis, and Mechanics: A Computational Perspective. J Funct Biomater 2020; 11:jfb11010013. [PMID: 32121053 PMCID: PMC7151609 DOI: 10.3390/jfb11010013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/27/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023] Open
Abstract
Tissue engineering, with the goal of repairing or replacing damaged tissue and organs, has continued to make dramatic science-based advances since its origins in the late 1980’s and early 1990’s. Such advances are always multi-disciplinary in nature, from basic biology and chemistry through physics and mathematics to various engineering and computer fields. This review will focus its attention on two topics critical for tissue engineering liver development: (a) fluid flow, zonation, and drug screening, and (b) biomechanics, tissue stiffness, and fibrosis, all within the context of 3D structures. First, a general overview of various bioreactor designs developed to investigate fluid transport and tissue biomechanics is given. This includes a mention of computational fluid dynamic methods used to optimize and validate these designs. Thereafter, the perspective provided by computer simulations of flow, reactive transport, and biomechanics responses at the scale of the liver lobule and liver tissue is outlined, in addition to how bioreactor-measured properties can be utilized in these models. Here, the fundamental issues of tortuosity and upscaling are highlighted, as well as the role of disease and fibrosis in these issues. Some idealized simulations of the effects of fibrosis on lobule drug transport and mechanics responses are provided to further illustrate these concepts. This review concludes with an outline of some practical applications of tissue engineering advances and how efficient computational upscaling techniques, such as dual continuum modeling, might be used to quantify the transition of bioreactor results to the full liver scale.
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Ho H, Yu HB, Bartlett A, Hunter P. An in silico pipeline for subject-specific hemodynamics analysis in liver surgery planning. Comput Methods Biomech Biomed Engin 2020; 23:138-142. [PMID: 31928213 DOI: 10.1080/10255842.2019.1708335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The progresses in fast simulations of the hepatic flow in subject-specific vascular tree have created new toolkits for pre-surgical planning. The aim of this short communication is to introduce a computational pipeline that integrates several recently developed in silico liver models and algorithms. Firstly, a semi-automatic segmentation pipeline is used to digitise hepatic vessels. Then, a constructive constraint optimisation (CCO) algorithm is used to extend the digitised vascular tree, and also to compute the blood pressure and flow velocity in the tree. Couinaud segments are simulated from the diffusion zones of the portal venous tree. The constructed surgical planning model is then deployed cross-platform for use in various scenarios.
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Affiliation(s)
- H Ho
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - H B Yu
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - A Bartlett
- New Zealand Liver Transplant Unit, Auckland City Hospital, Auckland, New Zealand
| | - P Hunter
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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11
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Ma R, Hunter P, Cousins W, Ho H, Bartlett A, Safaei S. Anatomically based simulation of hepatic perfusion in the human liver. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3229. [PMID: 31368204 DOI: 10.1002/cnm.3229] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 06/19/2019] [Accepted: 06/19/2019] [Indexed: 06/10/2023]
Abstract
Liver structures of a healthy subject are digitised and segmented from computed tomography (CT) images, and hepatic perfusion is modelled in the hepatic artery and portal vein of the healthy subject with structured tree-based outflow boundary conditions. This self-similar structured tree is widely used in the literature, eg, blood flow simulation in larger systemic arteries and cerebral circulation, and is used in this study to model the effect of the smaller hepatic arteries and arterioles, as well as the smaller hepatic portal veins and portal venules. Physiologically reasonable results are obtained. Since the structured tree terminates at the size of the microvasculature system in liver lobules, the structured tree boundary condition will enable the proposed organ-level model of hepatic arterial flow to be easily connected to tissue-level models of liver lobules. Blood flow in the hepatic vein is also modelled in this subject with three-element Windkessel model as outflow boundary conditions. The benefit of integrating the perfusion in all hepatic vascular vessels is that it helps us analyse some complicated clinical phenomenon more efficiently, eg, one possible application is to obtain the portal pressure gradient (PPG) to help examine the reliability of hepatic venous pressure gradient (HVPG) as an indirect measure of portal pressure. Moreover, since four to six generations of hepatic vessels, which are sufficient for liver classification analysis, were employed in the model, this study is setting the computational foundation of a potentially handy surgical tool.
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Affiliation(s)
- Renfei Ma
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Peter Hunter
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | | | - Harvey Ho
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Adam Bartlett
- Department of Surgery, University of Auckland, Auckland, New Zealand
- Liver Research Unit, Auckland City Hospital, Auckland, New Zealand
| | - Soroush Safaei
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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12
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Kopylova VS, Boronovskiy SE, Nartsissov YR. Fundamental constraints of vessels network architecture properties revealed by reconstruction of a rat brain vasculature. Math Biosci 2019; 315:108237. [PMID: 31377216 DOI: 10.1016/j.mbs.2019.108237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 07/31/2019] [Accepted: 07/31/2019] [Indexed: 10/26/2022]
Abstract
The studies of mammalian vasculature are an essential part of biomedical research, enabling the development of physiological understanding and forming the background of medical techniques and therapy. Despite the fact that the basic principles of vessel network description were established in the first quarter of the twentieth century, a digital model describing the vasculature in full accordance with experimental data has not yet been created. In the present study, we combine the determined structure design of basic arterial vessels with the stochastic creation of small vessel networks. By the example of rat brain arterial network model it was shown that the arterial blood volume and the magnitude of the blood flow impose a limitation on the network architecture. In particular, the bifurcation exponent (γ) should not be less than 2.7, and the optimal value of this parameter lies in the range of 2.9-3.0. Although the networks with a low γ appear as branched and complex, they do not fill out the phantom properly. Thus, the architecture of the vasculature is fundamentally determined by topological geometrical parameters.
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Affiliation(s)
- V S Kopylova
- Department of mathematical modelling and statistical analysis, Institute of cytochemistry and molecular pharmacology, Moscow, Russia.
| | - S E Boronovskiy
- Department of mathematical modelling and statistical analysis, Institute of cytochemistry and molecular pharmacology, Moscow, Russia
| | - Ya R Nartsissov
- Department of mathematical modelling and statistical analysis, Institute of cytochemistry and molecular pharmacology, Moscow, Russia
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Kretz D, Hesser J, Glatting G, Diehl S, Wenz F, He W, Zheng L. Modeling sphere dynamics in blood vessels for SIRT pre-planning - To fathom the potential and limitations. Z Med Phys 2018; 29:5-15. [PMID: 30049550 DOI: 10.1016/j.zemedi.2018.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 05/26/2018] [Accepted: 05/27/2018] [Indexed: 11/26/2022]
Abstract
For selective internal radiation therapy (SIRT) the calculation of the 3D distribution of spheres based on individual blood flow properties is still an open and relevant research question. The purpose of this work is to develop and analyze a new treatment planning method for SIRT to calculate the absorbed dose distribution. For this intention, flow dynamics of the SIRT-spheres inside the blood vessels was simulated. The challenge is treatment planning solely using high-resolution imaging data available before treatment. The resolution required to reliably predict the sphere distribution and hence the dose was investigated. For this purpose, arteries of the liver were segmented from a contrast-enhanced angiographic CT. Due to the limited resolution of the given CT, smaller vessels were generated via a vessel model. A combined 1D/3D-flow simulation model was implemented to simulate the final 3D distribution of spheres and dose. Results were evaluated against experimental data from Y90-PET. Analysis showed that the resolution of the vessels within the angiographic CT of about 0.5mm should be improved to a limit of about 150μm to reach a reliable prediction.
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Affiliation(s)
- Dominik Kretz
- Experimental Radiation Oncology, Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Germany.
| | - Jürgen Hesser
- Experimental Radiation Oncology, Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Germany; Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Germany; Central Institute of Mental Health (ZI), Mannheim, Germany
| | - Gerhard Glatting
- Medical Radiation Physics/Radiation Protection, Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Steffen Diehl
- Department of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Germany
| | - Frederik Wenz
- Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Germany
| | - Wanji He
- Experimental Radiation Oncology, Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Germany
| | - Lei Zheng
- Experimental Radiation Oncology, Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Germany
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Rohan E, Lukeš V, Jonášová A. Modeling of the contrast-enhanced perfusion test in liver based on the multi-compartment flow in porous media. J Math Biol 2018; 77:421-454. [PMID: 29368273 DOI: 10.1007/s00285-018-1209-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 01/15/2018] [Indexed: 12/20/2022]
Abstract
The paper deals with modeling the liver perfusion intended to improve quantitative analysis of the tissue scans provided by the contrast-enhanced computed tomography (CT). For this purpose, we developed a model of dynamic transport of the contrast fluid through the hierarchies of the perfusion trees. Conceptually, computed time-space distributions of the so-called tissue density can be compared with the measured data obtained from CT; such a modeling feedback can be used for model parameter identification. The blood flow is characterized at several scales for which different models are used. Flows in upper hierarchies represented by larger branching vessels are described using simple 1D models based on the Bernoulli equation extended by correction terms to respect the local pressure losses. To describe flows in smaller vessels and in the tissue parenchyma, we propose a 3D continuum model of porous medium defined in terms of hierarchically matched compartments characterized by hydraulic permeabilities. The 1D models corresponding to the portal and hepatic veins are coupled with the 3D model through point sources, or sinks. The contrast fluid saturation is governed by transport equations adapted for the 1D and 3D flow models. The complex perfusion model has been implemented using the finite element and finite volume methods. We report numerical examples computed for anatomically relevant geometries of the liver organ and of the principal vascular trees. The simulated tissue density corresponding to the CT examination output reflects a pathology modeled as a localized permeability deficiency.
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Affiliation(s)
- Eduard Rohan
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Univerzitní 8, 30614, Pilsen, Czech Republic.
| | - Vladimír Lukeš
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Univerzitní 8, 30614, Pilsen, Czech Republic
| | - Alena Jonášová
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Univerzitní 8, 30614, Pilsen, Czech Republic
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15
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Merrem A, Bartzsch S, Laissue J, Oelfke U. Computational modelling of the cerebral cortical microvasculature: effect of x-ray microbeams versus broad beam irradiation. Phys Med Biol 2017; 62:3902-3922. [PMID: 28333689 PMCID: PMC6050522 DOI: 10.1088/1361-6560/aa68d5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 03/15/2017] [Accepted: 03/23/2017] [Indexed: 12/31/2022]
Abstract
Microbeam Radiation Therapy is an innovative pre-clinical strategy which uses arrays of parallel, tens of micrometres wide kilo-voltage photon beams to treat tumours. These x-ray beams are typically generated on a synchrotron source. It was shown that these beam geometries allow exceptional normal tissue sparing from radiation damage while still being effective in tumour ablation. A final biological explanation for this enhanced therapeutic ratio has still not been found, some experimental data support an important role of the vasculature. In this work, the effect of microbeams on a normal microvascular network of the cerebral cortex was assessed in computer simulations and compared to the effect of homogeneous, seamless exposures at equal energy absorption. The anatomy of a cerebral microvascular network and the inflicted radiation damage were simulated to closely mimic experimental data using a novel probabilistic model of radiation damage to blood vessels. It was found that the spatial dose fractionation by microbeam arrays significantly decreased the vascular damage. The higher the peak-to-valley dose ratio, the more pronounced the sparing effect. Simulations of the radiation damage as a function of morphological parameters of the vascular network demonstrated that the distribution of blood vessel radii is a key parameter determining both the overall radiation damage of the vasculature and the dose-dependent differential effect of microbeam irradiation.
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Affiliation(s)
- A Merrem
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany
- This work was carried out at the German Cancer Research Center, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany
| | - S Bartzsch
- Klinikum Rechts der Isar, Ismaninger Str. 2, 81675 München, Germany
- The Institute of Cancer Research, Royal Marsden Hospital, Fulham Rd, London SW3 6JJ, United Kingdom
- This work was carried out at the German Cancer Research Center, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany
| | - J Laissue
- University of Bern, Hochschulstrasse 4, 3012 Bern, Switzerland
| | - U Oelfke
- The Institute of Cancer Research, Royal Marsden Hospital, Fulham Rd, London SW3 6JJ, United Kingdom
- This work was carried out at the German Cancer Research Center, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany
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16
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Peeters G, Debbaut C, Laleman W, Monbaliu D, Vander Elst I, Detrez JR, Vandecasteele T, De Schryver T, Van Hoorebeke L, Favere K, Verbeke J, Segers P, Cornillie P, De Vos WH. A multilevel framework to reconstruct anatomical 3D models of the hepatic vasculature in rat livers. J Anat 2016; 230:471-483. [PMID: 27995631 DOI: 10.1111/joa.12567] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2016] [Indexed: 12/21/2022] Open
Abstract
The intricate (micro)vascular architecture of the liver has not yet been fully unravelled. Although current models are often idealized simplifications of the complex anatomical reality, correct morphological information is instrumental for scientific and clinical purposes. Previously, both vascular corrosion casting (VCC) and immunohistochemistry (IHC) have been separately used to study the hepatic vasculature. Nevertheless, these techniques still face a number of challenges such as dual casting in VCC and limited imaging depths for IHC. We have optimized both techniques and combined their complementary strengths to develop a framework for multilevel reconstruction of the hepatic circulation in the rat. The VCC and micro-CT scanning protocol was improved by enabling dual casting, optimizing the contrast agent concentration, and adjusting the viscosity of the resin (PU4ii). IHC was improved with an optimized clearing technique (CUBIC) that extended the imaging depth for confocal microscopy more than five-fold. Using in-house developed software (DeLiver), the vascular network - in both VCC and IHC datasets - was automatically segmented and/or morphologically analysed. Our methodological framework allows 3D reconstruction and quantification of the hepatic circulation, ranging from the major blood vessels down to the intertwined and interconnected sinusoids. We believe that the presented framework will have value beyond studies of the liver, and will facilitate a better understanding of various parenchymal organs in general, in physiological and pathological circumstances.
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Affiliation(s)
- Geert Peeters
- IBiTech - bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Charlotte Debbaut
- IBiTech - bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Wim Laleman
- Gastroenterology & Hepatology, University Hospitals Leuven, Leuven, Belgium.,Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Diethard Monbaliu
- Abdominal Transplant Surgery, University Hospitals Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Ingrid Vander Elst
- Gastroenterology & Hepatology, University Hospitals Leuven, Leuven, Belgium.,Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Jan R Detrez
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Tim Vandecasteele
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Thomas De Schryver
- Center for X-Ray Tomography, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Luc Van Hoorebeke
- Center for X-Ray Tomography, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Kasper Favere
- IBiTech - bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Jonas Verbeke
- IBiTech - bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Patrick Segers
- IBiTech - bioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Pieter Cornillie
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Winnok H De Vos
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium.,Cell Systems and Imaging, Department of Molecular Biotechnology, University of Ghent, Ghent, Belgium
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17
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Högberg J, Rizell M, Hultborn R, Svensson J, Henrikson O, Mölne J, Gjertsson P, Bernhardt P. Simulation Model of Microsphere Distribution for Selective Internal Radiation Therapy Agrees With Observations. Int J Radiat Oncol Biol Phys 2016; 96:414-421. [DOI: 10.1016/j.ijrobp.2016.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/19/2016] [Accepted: 05/05/2016] [Indexed: 01/07/2023]
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18
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Safaei S, Bradley CP, Suresh V, Mithraratne K, Muller A, Ho H, Ladd D, Hellevik LR, Omholt SW, Chase JG, Müller LO, Watanabe SM, Blanco PJ, de Bono B, Hunter PJ. Roadmap for cardiovascular circulation model. J Physiol 2016; 594:6909-6928. [PMID: 27506597 DOI: 10.1113/jp272660] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/02/2016] [Indexed: 11/08/2022] Open
Abstract
Computational models of many aspects of the mammalian cardiovascular circulation have been developed. Indeed, along with orthopaedics, this area of physiology is one that has attracted much interest from engineers, presumably because the equations governing blood flow in the vascular system are well understood and can be solved with well-established numerical techniques. Unfortunately, there have been only a few attempts to create a comprehensive public domain resource for cardiovascular researchers. In this paper we propose a roadmap for developing an open source cardiovascular circulation model. The model should be registered to the musculo-skeletal system. The computational infrastructure for the cardiovascular model should provide for near real-time computation of blood flow and pressure in all parts of the body. The model should deal with vascular beds in all tissues, and the computational infrastructure for the model should provide links into CellML models of cell function and tissue function. In this work we review the literature associated with 1D blood flow modelling in the cardiovascular system, discuss model encoding standards, software and a model repository. We then describe the coordinate systems used to define the vascular geometry, derive the equations and discuss the implementation of these coupled equations in the open source computational software OpenCMISS. Finally, some preliminary results are presented and plans outlined for the next steps in the development of the model, the computational software and the graphical user interface for accessing the model.
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Affiliation(s)
- Soroush Safaei
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | - Vinod Suresh
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - Kumar Mithraratne
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Alexandre Muller
- ENSEEIHT, National Polytechnic Institute of Toulouse, Toulouse, France
| | - Harvey Ho
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - David Ladd
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Leif R Hellevik
- Faculty of Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Stig W Omholt
- Faculty of Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - J Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Lucas O Müller
- LNCC/MCTI, National Laboratory for Scientific Computing, Petrópolis, Brazil
| | | | - Pablo J Blanco
- LNCC/MCTI, National Laboratory for Scientific Computing, Petrópolis, Brazil
| | - Bernard de Bono
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Institute of Health Informatics, University College London, London, UK
| | - Peter J Hunter
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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19
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White D, Coombe D, Rezania V, Tuszynski J. Building a 3D Virtual Liver: Methods for Simulating Blood Flow and Hepatic Clearance on 3D Structures. PLoS One 2016; 11:e0162215. [PMID: 27649537 PMCID: PMC5029923 DOI: 10.1371/journal.pone.0162215] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/18/2016] [Indexed: 01/18/2023] Open
Abstract
In this paper, we develop a spatio-temporal modeling approach to describe blood and drug flow, as well as drug uptake and elimination, on an approximation of the liver. Extending on previously developed computational approaches, we generate an approximation of a liver, which consists of a portal and hepatic vein vasculature structure, embedded in the surrounding liver tissue. The vasculature is generated via constrained constructive optimization, and then converted to a spatial grid of a selected grid size. Estimates for surrounding upscaled lobule tissue properties are then presented appropriate to the same grid size. Simulation of fluid flow and drug metabolism (hepatic clearance) are completed using discretized forms of the relevant convective-diffusive-reactive partial differential equations for these processes. This results in a single stage, uniformly consistent method to simulate equations for blood and drug flow, as well as drug metabolism, on a 3D structure representative of a liver.
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Affiliation(s)
- Diana White
- Department of Mathematics, Clarkson University, Potsdam, New York, United States of America
| | - Dennis Coombe
- Computer Modelling Group Ltd, Calgary, Alberta, Canada
| | - Vahid Rezania
- Department of Physical Sciences, MacEwan University, Edmonton, Alberta, Canada
| | - Jack Tuszynski
- Department of Physics and Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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20
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Quantification of Hepatic Vascular and Parenchymal Regeneration in Mice. PLoS One 2016; 11:e0160581. [PMID: 27494255 PMCID: PMC4975469 DOI: 10.1371/journal.pone.0160581] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/21/2016] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Liver regeneration consists of cellular proliferation leading to parenchymal and vascular growth. This study complements previous studies on cellular proliferation and weight recovery by (1) quantitatively describing parenchymal and vascular regeneration, and (2) determining their relationship. Both together are needed to (3) characterize the underlying growth pattern. METHODS Specimens were created by injecting a polymerizing contrast agent in either portal or hepatic vein in normal or regenerating livers after 70% partial hepatectomy. 3D image data were obtained through micro-CT scanning. Parenchymal growth was assessed by determining weight and volume of the regenerating liver. Vascular growth was described by manually determined circumscribed parameters (maximal vessel length and radius of right inferior portal/hepatic vein), automatically determined cumulative parameters (total edge length and total vascular volume), and parameters describing vascular density (total edge length/volume, vascular volume fraction). The growth pattern was explored by comparing the relative increase of these parameters to the increase expected in case of isotropic expansion. RESULTS Liver volume recovery paralleled weight recovery and reached 90% of the original liver volume within 7 days. Comparing radius-related vascular parameters immediately after surgical resection and after virtual resection in-silico revealed a slight increase, possibly reflecting the effect of resection-induced portal hyperperfusion. Comparing length-related parameters between post-operative day 7 and after virtual resection showed similar vascular growth in both vascular systems investigated. In contrast, radius-related parameters increased slightly more in the portal vein. Despite the seemingly homogeneous 3D growth, the observed vascular parameters were not compatible with the hypothesis of isotropic expansion of liver parenchyma and vascular structures. CONCLUSION We present an approach for the quantitative analysis of the vascular systems of regenerating mouse livers. We applied this technique for assessing the hepatic growth pattern. Prospectively, this approach can be used to investigate hepatic vascular regeneration under different conditions.
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21
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Vartak N, Damle‐Vartak A, Richter B, Dirsch O, Dahmen U, Hammad S, Hengstler JG. Cholestasis-induced adaptive remodeling of interlobular bile ducts. Hepatology 2016; 63:951-64. [PMID: 26610202 PMCID: PMC5066759 DOI: 10.1002/hep.28373] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 11/25/2015] [Indexed: 12/24/2022]
Abstract
UNLABELLED Cholestasis is a common complication in liver diseases that triggers a proliferative response of the biliary tree. Bile duct ligation (BDL) is a frequently used model of cholestasis in rodents. To determine which changes occur in the three-dimensional (3D) architecture of the interlobular bile duct during cholestasis, we used 3D confocal imaging, surface reconstructions, and automated image quantification covering a period up to 28 days after BDL. We show a highly reproducible sequence of interlobular duct remodeling, where cholangiocyte proliferation initially causes corrugation of the luminal duct surface, leading to an approximately five-fold increase in surface area. This is analogous to the function of villi in the intestine or sulci in the brain, where an expansion of area is achieved within a restricted volume. The increase in surface area is further enhanced by duct branching, branch elongation, and loop formation through self-joining, whereby an initially relatively sparse mesh surrounding the portal vein becomes five-fold denser through elongation, corrugation, and ramification. The number of connections between the bile duct and the lobular bile canalicular network by the canals of Hering decreases proportionally to the increase in bile duct length, suggesting that no novel connections are established. The diameter of the interlobular bile duct remains constant after BDL, a response that is qualitatively distinct from that of large bile ducts, which tend to enlarge their diameters. Therefore, volume enhancement is only due to net elongation of the ducts. Because curvature and tortuosity of the bile duct are unaltered, this enlargement of the biliary tree is caused by branching and not by convolution. CONCLUSION BDL causes adaptive remodeling that aims at optimizing the intraluminal surface area by way of corrugation and branching.
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Affiliation(s)
- Nachiket Vartak
- Department of Systems ToxicologyLeibniz Institute for Work Physiology and Human Factors (IfADo) at TU DortmundDortmundGermany
| | - Amruta Damle‐Vartak
- Department of Systems ToxicologyLeibniz Institute for Work Physiology and Human Factors (IfADo) at TU DortmundDortmundGermany
| | - Beate Richter
- Department of Experimental Transplantation SurgeryUniversity Clinic JenaJenaGermany
| | - Olaf Dirsch
- Department of Experimental Transplantation SurgeryUniversity Clinic JenaJenaGermany
| | - Uta Dahmen
- Department of Experimental Transplantation SurgeryUniversity Clinic JenaJenaGermany
| | - Seddik Hammad
- Department of Systems ToxicologyLeibniz Institute for Work Physiology and Human Factors (IfADo) at TU DortmundDortmundGermany,Faculty of Veterinary MedicineSouth Valley UniversityQenaEgypt
| | - Jan G. Hengstler
- Department of Systems ToxicologyLeibniz Institute for Work Physiology and Human Factors (IfADo) at TU DortmundDortmundGermany
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22
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Living Donor Liver Transplantation in Children: Surgical and Immunological Results in 250 Recipients at Université Catholique de Louvain. Ann Surg 2016; 262:1141-9. [PMID: 25563870 DOI: 10.1097/sla.0000000000001094] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVES To evaluate the outcome of pediatric living donor liver transplantation (LDLT) regarding portal vein (PV) reconstruction, ABO compatibility, and impact of maternal donation on graft acceptance. BACKGROUND LDLT and ABO-mismatched transplantation constitute feasible options to alleviate organ shortage in children. Vascular complications of portal hypoplasia in biliary atresia (BA) and acute rejection (AR) are still major concerns in this field. METHODS Data from 250 pediatric LDLT recipients, performed at Cliniques Universitaires Saint-Luc between July 1993 and June 2012, were collected retrospectively. Results were analyzed according to ABO matching and PV complications. Uni- and multivariate analyses were performed to study the impact of immunosuppression, sex matching, and maternal donation on AR rate. RESULTS Overall, the 10-year patient survival rate was 93.2%. Neither patient or graft loss nor vascular rejection, nor hemolysis, was encountered in the ABO nonidentical patients (n = 58), provided pretransplant levels of relevant isoagglutinins were below 1/16. In BA recipients, the rate of PV complications was lower after portoplasty (4.6%) than after truncal PV anastomosis (9.8%) and to jump graft interposition (26.9%; P = 0.027). In parental donation, maternal grafts were associated with higher 1-year AR-free survival (55.2%) than paternal grafts (39.8%; P = 0.041), but only in BA patients. CONCLUSIONS LDLT, including ABO-mismatched transplantation, constitutes a safe and efficient therapy for liver failure in children. In BA patients with PV hypoplasia, portoplasty seems to constitute the best technique for PV reconstruction. Maternal donation might be a protective factor for AR.
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23
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Song S, Yang J, Fan J, Cong W, Ai D, Zhao Y, Wang Y. Geometrical force constraint method for vessel and x-ray angiogram simulation. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2016; 24:87-106. [PMID: 26890908 DOI: 10.3233/xst-160539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This study proposes a novel geometrical force constraint method for 3-D vasculature modeling and angiographic image simulation. For this method, space filling force, gravitational force, and topological preserving force are proposed and combined for the optimization of the topology of the vascular structure. The surface covering force and surface adhesion force are constructed to drive the growth of the vasculature on any surface. According to the combination effects of the topological and surface adhering forces, a realistic vasculature can be effectively simulated on any surface. The image projection of the generated 3-D vascular structures is simulated according to the perspective projection and energy attenuation principles of X-rays. Finally, the simulated projection vasculature is fused with a predefined angiographic mask image to generate a realistic angiogram. The proposed method is evaluated on a CT image and three generally utilized surfaces. The results fully demonstrate the effectiveness and robustness of the proposed method.
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24
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Schwen LO, Schenk A, Kreutz C, Timmer J, Bartolomé Rodríguez MM, Kuepfer L, Preusser T. Representative Sinusoids for Hepatic Four-Scale Pharmacokinetics Simulations. PLoS One 2015. [PMID: 26222615 PMCID: PMC4519332 DOI: 10.1371/journal.pone.0133653] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mammalian liver plays a key role for metabolism and detoxification of xenobiotics in the body. The corresponding biochemical processes are typically subject to spatial variations at different length scales. Zonal enzyme expression along sinusoids leads to zonated metabolization already in the healthy state. Pathological states of the liver may involve liver cells affected in a zonated manner or heterogeneously across the whole organ. This spatial heterogeneity, however, cannot be described by most computational models which usually consider the liver as a homogeneous, well-stirred organ. The goal of this article is to present a methodology to extend whole-body pharmacokinetics models by a detailed liver model, combining different modeling approaches from the literature. This approach results in an integrated four-scale model, from single cells via sinusoids and the organ to the whole organism, capable of mechanistically representing metabolization inhomogeneity in livers at different spatial scales. Moreover, the model shows circulatory mixing effects due to a delayed recirculation through the surrounding organism. To show that this approach is generally applicable for different physiological processes, we show three applications as proofs of concept, covering a range of species, compounds, and diseased states: clearance of midazolam in steatotic human livers, clearance of caffeine in mouse livers regenerating from necrosis, and a parameter study on the impact of different cell entities on insulin uptake in mouse livers. The examples illustrate how variations only discernible at the local scale influence substance distribution in the plasma at the whole-body level. In particular, our results show that simultaneously considering variations at all relevant spatial scales may be necessary to understand their impact on observations at the organism scale.
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Affiliation(s)
| | - Arne Schenk
- Computational Systems Biology, Bayer Technology Services, Leverkusen, Germany
- Aachen Institute for Advanced Study in Computational Engineering Sciences, RWTH Aachen University, Aachen, Germany
| | - Clemens Kreutz
- Freiburg Center for Data Analysis and Modeling (FDM), Institute of Physics, University of Freiburg, Freiburg, Germany
| | - Jens Timmer
- Freiburg Center for Data Analysis and Modeling (FDM), Institute of Physics, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | | | - Lars Kuepfer
- Computational Systems Biology, Bayer Technology Services, Leverkusen, Germany
- Institute of Applied Microbiology, RWTH Aachen University, Aachen, Germany
| | - Tobias Preusser
- Fraunhofer MEVIS, Bremen, Germany
- Jacobs University, Bremen, Germany
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25
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Shestopaloff YK. Method for finding metabolic properties based on the general growth law. Liver examples. A general framework for biological modeling. PLoS One 2014; 9:e99836. [PMID: 24940740 PMCID: PMC4062463 DOI: 10.1371/journal.pone.0099836] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/19/2014] [Indexed: 11/18/2022] Open
Abstract
We propose a method for finding metabolic parameters of cells, organs and whole organisms, which is based on the earlier discovered general growth law. Based on the obtained results and analysis of available biological models, we propose a general framework for modeling biological phenomena and discuss how it can be used in Virtual Liver Network project. The foundational idea of the study is that growth of cells, organs, systems and whole organisms, besides biomolecular machinery, is influenced by biophysical mechanisms acting at different scale levels. In particular, the general growth law uniquely defines distribution of nutritional resources between maintenance needs and biomass synthesis at each phase of growth and at each scale level. We exemplify the approach considering metabolic properties of growing human and dog livers and liver transplants. A procedure for verification of obtained results has been introduced too. We found that two examined dogs have high metabolic rates consuming about 0.62 and 1 gram of nutrients per cubic centimeter of liver per day, and verified this using the proposed verification procedure. We also evaluated consumption rate of nutrients in human livers, determining it to be about 0.088 gram of nutrients per cubic centimeter of liver per day for males, and about 0.098 for females. This noticeable difference can be explained by evolutionary development, which required females to have greater liver processing capacity to support pregnancy. We also found how much nutrients go to biomass synthesis and maintenance at each phase of liver and liver transplant growth. Obtained results demonstrate that the proposed approach can be used for finding metabolic characteristics of cells, organs, and whole organisms, which can further serve as important inputs and constraints for many applications in biology (such as protein expression), biotechnology (synthesis of substances), and medicine.
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26
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Schwen LO, Krauss M, Niederalt C, Gremse F, Kiessling F, Schenk A, Preusser T, Kuepfer L. Spatio-temporal simulation of first pass drug perfusion in the liver. PLoS Comput Biol 2014; 10:e1003499. [PMID: 24625393 PMCID: PMC3952820 DOI: 10.1371/journal.pcbi.1003499] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 01/21/2014] [Indexed: 01/21/2023] Open
Abstract
The liver is the central organ for detoxification of xenobiotics in the body. In pharmacokinetic modeling, hepatic metabolization capacity is typically quantified as hepatic clearance computed as degradation in well-stirred compartments. This is an accurate mechanistic description once a quasi-equilibrium between blood and surrounding tissue is established. However, this model structure cannot be used to simulate spatio-temporal distribution during the first instants after drug injection. In this paper, we introduce a new spatially resolved model to simulate first pass perfusion of compounds within the naive liver. The model is based on vascular structures obtained from computed tomography as well as physiologically based mass transfer descriptions obtained from pharmacokinetic modeling. The physiological architecture of hepatic tissue in our model is governed by both vascular geometry and the composition of the connecting hepatic tissue. In particular, we here consider locally distributed mass flow in liver tissue instead of considering well-stirred compartments. Experimentally, the model structure corresponds to an isolated perfused liver and provides an ideal platform to address first pass effects and questions of hepatic heterogeneity. The model was evaluated for three exemplary compounds covering key aspects of perfusion, distribution and metabolization within the liver. As pathophysiological states we considered the influence of steatosis and carbon tetrachloride-induced liver necrosis on total hepatic distribution and metabolic capacity. Notably, we found that our computational predictions are in qualitative agreement with previously published experimental data. The simulation results provide an unprecedented level of detail in compound concentration profiles during first pass perfusion, both spatio-temporally in liver tissue itself and temporally in the outflowing blood. We expect our model to be the foundation of further spatially resolved models of the liver in the future.
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Affiliation(s)
| | - Markus Krauss
- Computational Systems Biology, Bayer Technology Services, Leverkusen, Germany
- Aachen Institute for Advanced Study in Computational Engineering Sciences, RWTH Aachen University, Aachen, Germany
| | - Christoph Niederalt
- Computational Systems Biology, Bayer Technology Services, Leverkusen, Germany
| | - Felix Gremse
- Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Fabian Kiessling
- Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | | | - Tobias Preusser
- Fraunhofer MEVIS, Bremen, Germany
- School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Lars Kuepfer
- Computational Systems Biology, Bayer Technology Services, Leverkusen, Germany
- Institute of Applied Microbiology, RWTH Aachen University, Aachen, Germany
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27
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Walrand S, Hesse M, Chiesa C, Lhommel R, Jamar F. The Low Hepatic Toxicity per Gray of 90Y Glass Microspheres Is Linked to Their Transport in the Arterial Tree Favoring a Nonuniform Trapping as Observed in Posttherapy PET Imaging. J Nucl Med 2013; 55:135-40. [DOI: 10.2967/jnumed.113.126839] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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