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Pohlmann A, Cantow K, Huelnhagen T, Grosenick D, Dos Santos Periquito J, Boehmert L, Gladytz T, Waiczies S, Flemming B, Seeliger E, Niendorf T. Experimental MRI Monitoring of Renal Blood Volume Fraction Variations En Route to Renal Magnetic Resonance Oximetry. ACTA ACUST UNITED AC 2017; 3:188-200. [PMID: 30042981 PMCID: PMC6024389 DOI: 10.18383/j.tom.2017.00012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Diagnosis of early-stage acute kidney injury (AKI) will benefit from a timely identification of local tissue hypoxia. Renal tissue hypoxia is an early feature in AKI pathophysiology, and renal oxygenation is increasingly being assessed through T2*-weighted magnetic resonance imaging (MRI). However, changes in renal blood volume fraction (BVf) confound renal T2*. The aim of this study was to assess the feasibility of intravascular contrast-enhanced MRI for monitoring renal BVf during physiological interventions that are concomitant with variations in BVf and to explore the possibility of correcting renal T2* for BVf variations. A dose-dependent study of the contrast agent ferumoxytol was performed in rats. BVf was monitored throughout short-term occlusion of the renal vein, which is known to markedly change renal blood partial pressure of O2 and BVf. BVf calculated from MRI measurements was used to estimate oxygen saturation of hemoglobin (SO2). BVf and SO2 were benchmarked against cortical data derived from near-infrared spectroscopy. As estimated from magnetic resonance parametric maps of T2 and T2*, BVf was shown to increase, whereas SO2 was shown to decline during venous occlusion (VO). This observation could be quantitatively reproduced in test–retest scenarios. Changes in BVf and SO2 were in good agreement with data obtained from near-infrared spectroscopy. Our findings provide motivation to advance multiparametric MRI for studying AKIs, with the ultimate goal of translating MRI-based renal BVf mapping into clinical practice en route noninvasive renal magnetic resonance oximetry as a method of assessing AKI and progression to chronic damage.
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Affiliation(s)
- Andreas Pohlmann
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Germany
| | - Kathleen Cantow
- Institute of Physiology and Center for Cardiovascular Research, Charité - Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Till Huelnhagen
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Germany
| | - Dirk Grosenick
- Physikalisch-Technische-Bundesanstalt (PTB), Berlin, Germany
| | - Joāo Dos Santos Periquito
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Germany
| | - Laura Boehmert
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Germany
| | - Thomas Gladytz
- Physikalisch-Technische-Bundesanstalt (PTB), Berlin, Germany
| | - Sonia Waiczies
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Germany
| | - Bert Flemming
- Institute of Physiology and Center for Cardiovascular Research, Charité - Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Erdmann Seeliger
- Institute of Physiology and Center for Cardiovascular Research, Charité - Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Thoralf Niendorf
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Germany.,Experimental and Clinical Research Center, Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; and.,Deutsches Zentrum für Herz- Kreislauf-Forschung (DZHK; German Centre for Cardiovascular Research), Berlin, Germany
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Abstract
A body of finite size is moving freely inside, and interacting with, a channel flow. The description of this unsteady interaction for a comparatively dense thin body moving slowly relative to flow at medium-to-high Reynolds number shows that an inviscid core problem with vorticity determines much, but not all, of the dominant response. It is found that the lift induced on a body of length comparable to the channel width leads to differences in flow direction upstream and downstream on the body scale which are smoothed out axially over a longer viscous length scale; the latter directly affects the change in flow directions. The change is such that in any symmetric incident flow the ratio of slopes is found to be [Formula: see text], i.e. approximately 0.900969, independently of Reynolds number, wall shear stresses and velocity profile. The two axial scales determine the evolution of the body and the flow, always yielding instability. This unusual evolution and linear or nonlinear instability mechanism arise outside the conventional range of flow instability and are influenced substantially by the lateral positioning, length and axial velocity of the body.
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Affiliation(s)
- Frank T Smith
- Department of Mathematics , UCL , Gower Street, London WC1E 6BT, UK
| | - Edward R Johnson
- Department of Mathematics , UCL , Gower Street, London WC1E 6BT, UK
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Mitrou N, Braam B, Cupples WA. A gap junction inhibitor, carbenoxolone, induces spatiotemporal dispersion of renal cortical perfusion and impairs autoregulation. Am J Physiol Heart Circ Physiol 2016; 311:H582-91. [PMID: 27371687 DOI: 10.1152/ajpheart.00941.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 06/27/2016] [Indexed: 11/22/2022]
Abstract
Renal autoregulation dynamics originating from the myogenic response (MR) and tubuloglomerular feedback (TGF) can synchronize over large regions of the kidney surface, likely through gap junction-mediated electrotonic conduction and reflecting distributed operation of autoregulation. We tested the hypotheses that inhibition of gap junctions reduces spatial synchronization of autoregulation dynamics, abrogates spatial and temporal smoothing of renal perfusion, and impairs renal autoregulation. In male Long-Evans rats, we infused the gap junction inhibitor carbenoxolone (CBX) or the related glycyrrhizic acid (GZA) that does not block gap junctions into the renal artery and monitored renal blood flow (RBF) and surface perfusion by laser speckle contrast imaging. Neither CBX nor GZA altered RBF or mean surface perfusion. CBX preferentially increased spatial and temporal variation in the distribution of surface perfusion, increased spatial variation in the operating frequencies of the MR and TGF, and reduced phase coherence of TGF and increased its dispersion. CBX, but not GZA, impaired dynamic and steady-state autoregulation. Separately, infusion of the Rho kinase inhibitor Y-27632 paralyzed smooth muscle, grossly impaired dynamic autoregulation, and monotonically increased spatial variation of surface perfusion. These data suggest CBX inhibited gap junction communication, which in turn reduced the ability of TGF to synchronize among groups of nephrons. The results indicate that impaired autoregulation resulted from degraded synchronization, rather than the reverse. We show that network behavior in the renal vasculature is necessary for effective RBF autoregulation.
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Affiliation(s)
- Nicholas Mitrou
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; and
| | - Branko Braam
- Department of Physiology and Department of Medicine, Division of Nephrology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - William A Cupples
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; and
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Zamir M, Vercnocke AJ, Edwards PK, Anderson JL, Jorgensen SM, Ritman EL. Myocardial Perfusion: Characteristics of Distal Intramyocardial Arteriolar Trees. Ann Biomed Eng 2015; 43:2771-9. [PMID: 25952363 PMCID: PMC4618034 DOI: 10.1007/s10439-015-1325-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 04/16/2015] [Indexed: 11/30/2022]
Abstract
A combination of experimental, theoretical, and imaging methodologies is used to examine the hierarchical structure and function of intramyocardial arteriolar trees in porcine hearts to provide a window onto a region of myocardial microvasculature which has been difficult to fully explore so far. A total of 66 microvascular trees from 6 isolated myocardial specimens were analyzed, with a cumulative number of 2438 arteriolar branches greater than or equal to 40 μm lumen diameter. The distribution of flow rates within each tree was derived from an assumed power law relationship for that tree between the diameter of vessel segments and flow rates that are consistent with that power law and subject to conservation of mass along hierarchical structure of the tree. The results indicate that the power law index increases at levels of arteriolar vasculature closer to the capillary level, consistent with a concomitant decrease in shear stress acting on endothelial tissue. These results resolve a long standing predicament which could not be resolved previously because of lack of data about the 3D, interconnected, arterioles. In the context of myocardial perfusion, the results indicate that the coefficient of variation of flow rate in pre-capillary distal arterioles is high, suggesting that heterogeneity of flow rate in these arterioles is not entirely random but may be due at least in part to active control.
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Affiliation(s)
- Mair Zamir
- Departments of Applied Mathematics and of Medical Biophysics, Western University, 1151 Richmond Street, London, ON, N6A 5B7, Canada
| | - Andrew J Vercnocke
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN, 55905, USA
| | - Phillip K Edwards
- Biomedical Imaging Resource, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN, 55905, USA
| | - Jill L Anderson
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN, 55905, USA
| | - Steven M Jorgensen
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN, 55905, USA
| | - Erik L Ritman
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN, 55905, USA.
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Davey SK, Aung A, Agrawal G, Lim HL, Kar M, Varghese S. Embedded 3D Photopatterning of Hydrogels with Diverse and Complex Architectures for Tissue Engineering and Disease Models. Tissue Eng Part C Methods 2015; 21:1188-96. [PMID: 26154197 DOI: 10.1089/ten.tec.2015.0179] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Techniques that can create three-dimensional (3D) structures to provide architectural support for cells have a significant impact in generating complex and hierarchically organized tissues/organs. In recent times, a number of technologies, including photopatterning, have been developed to create such intricate 3D structures. In this study, we describe an easy-to-implement photopatterning approach, involving a conventional fluorescent microscope and a simple photomask, to encapsulate cells within spatially defined 3D structures. We have demonstrated the ease and the versatility of this approach by creating simple to complex as well as multilayered structures. We have extended this photopatterning approach to incorporate and spatially organize multiple cell types, thereby establishing coculture systems. Such cost-effective and easy-to-use approaches can greatly advance tissue engineering strategies.
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Affiliation(s)
- Shruti Krishna Davey
- 1 Department of Bioengineering, University of California-San Diego , La Jolla, California
| | - Aereas Aung
- 1 Department of Bioengineering, University of California-San Diego , La Jolla, California
| | - Gaurav Agrawal
- 1 Department of Bioengineering, University of California-San Diego , La Jolla, California
| | - Han Liang Lim
- 1 Department of Bioengineering, University of California-San Diego , La Jolla, California
| | - Mrityunjoy Kar
- 1 Department of Bioengineering, University of California-San Diego , La Jolla, California
| | - Shyni Varghese
- 1 Department of Bioengineering, University of California-San Diego , La Jolla, California.,2 Institute of Engineering in Medicine, University of California-San Diego , La Jolla, California
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6
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Sinclair MD, Lee J, Cookson AN, Rivolo S, Hyde ER, Smith NP. Measurement and modeling of coronary blood flow. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2015; 7:335-56. [PMID: 26123867 DOI: 10.1002/wsbm.1309] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 05/19/2015] [Accepted: 05/21/2015] [Indexed: 01/10/2023]
Abstract
Ischemic heart disease that comprises both coronary artery disease and microvascular disease is the single greatest cause of death globally. In this context, enhancing our understanding of the interaction of coronary structure and function is not only fundamental for advancing basic physiology but also crucial for identifying new targets for treating these diseases. A central challenge for understanding coronary blood flow is that coronary structure and function exhibit different behaviors across a range of spatial and temporal scales. While experimental studies have sought to understand this feature by isolating specific mechanisms, in tandem, computational modeling is increasingly also providing a unique framework to integrate mechanistic behaviors across different scales. In addition, clinical methods for assessing coronary disease severity are continuously being informed and updated by findings in basic physiology. Coupling these technologies, computational modeling of the coronary circulation is emerging as a bridge between the experimental and clinical domains, providing a framework to integrate imaging and measurements from multiple sources with mathematical descriptions of governing physical laws. State-of-the-art computational modeling is being used to combine mechanistic models with data to provide new insight into coronary physiology, optimization of medical technologies, and new applications to guide clinical practice.
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Affiliation(s)
- Matthew D Sinclair
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Jack Lee
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Andrew N Cookson
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Simone Rivolo
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Eoin R Hyde
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Nicolas P Smith
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK.,Department of Engineering, University of Auckland, Auckland, New Zealand
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7
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Sinclair M, Lee J, Schuster A, Chiribiri A, van den Wijngaard J, van Horssen P, Siebes M, Spaan JAE, Nagel E, Smith NP. Microsphere skimming in the porcine coronary arteries: Implications for flow quantification. Microvasc Res 2015; 100:59-70. [PMID: 25963318 DOI: 10.1016/j.mvr.2015.04.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/28/2015] [Accepted: 04/17/2015] [Indexed: 11/25/2022]
Abstract
Particle skimming is a phenomenon where particles suspended in fluid flowing through vessels distribute disproportionately to bulk fluid volume at junctions. Microspheres are considered a gold standard of intra-organ perfusion measurements and are used widely in studies of flow distribution and quantification. It has previously been hypothesised that skimming at arterial junctions is responsible for a systematic over-estimation of myocardial perfusion from microspheres at the subendocardium. Our objective is to integrate coronary arterial structure and microsphere distribution, imaged at high resolution, to test the hypothesis of microsphere skimming in a porcine left coronary arterial (LCA) network. A detailed network was reconstructed from cryomicrotome imaging data and a Poiseuille flow model was used to simulate flow. A statistical approach using Clopper-Pearson confidence intervals was applied to determine the prevalence of skimming at bifurcations in the LCA. Results reveal that microsphere skimming is most prevalent at bifurcations in the larger coronary arteries, namely the epicardial and transmural arteries. Bifurcations at which skimming was identified have significantly more asymmetric branching parameters. This finding suggests that when using thin transmural segments to quantify flow from microspheres, a skimming-related deposition bias may result in underestimation of perfusion in the subepicardium, and overestimation in the subendocardium.
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Affiliation(s)
- Matthew Sinclair
- Division of Imaging Sciences and Biomedical Engineering, King's College London, British Heart Foundation (BHF) Centre of Excellence, UK; National Institute of Heath Research (NIHR) Biomedical Research Centre at Guy's and St. Thomas' NHS Foundation Trust, Lambeth Wing, St. Thomas' Hospital, UK; Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC) Medical Engineering Centre, Lambeth Wing, St. Thomas' Hospital, London, UK
| | - Jack Lee
- Division of Imaging Sciences and Biomedical Engineering, King's College London, British Heart Foundation (BHF) Centre of Excellence, UK; National Institute of Heath Research (NIHR) Biomedical Research Centre at Guy's and St. Thomas' NHS Foundation Trust, Lambeth Wing, St. Thomas' Hospital, UK; Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC) Medical Engineering Centre, Lambeth Wing, St. Thomas' Hospital, London, UK
| | - Andreas Schuster
- Division of Imaging Sciences and Biomedical Engineering, King's College London, British Heart Foundation (BHF) Centre of Excellence, UK; National Institute of Heath Research (NIHR) Biomedical Research Centre at Guy's and St. Thomas' NHS Foundation Trust, Lambeth Wing, St. Thomas' Hospital, UK; Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC) Medical Engineering Centre, Lambeth Wing, St. Thomas' Hospital, London, UK; Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany; German Centre for Cardiovascular Research (DZHK, Partner Site Göttingen), Göttingen, Germany
| | - Amedeo Chiribiri
- Division of Imaging Sciences and Biomedical Engineering, King's College London, British Heart Foundation (BHF) Centre of Excellence, UK; National Institute of Heath Research (NIHR) Biomedical Research Centre at Guy's and St. Thomas' NHS Foundation Trust, Lambeth Wing, St. Thomas' Hospital, UK; Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC) Medical Engineering Centre, Lambeth Wing, St. Thomas' Hospital, London, UK
| | - Jeroen van den Wijngaard
- Department of Biomedical Engineering & Physics, Academic Medical Centre, Amsterdam, The Netherlands
| | - Pepijn van Horssen
- Department of Biomedical Engineering & Physics, Academic Medical Centre, Amsterdam, The Netherlands
| | - Maria Siebes
- Department of Biomedical Engineering & Physics, Academic Medical Centre, Amsterdam, The Netherlands
| | - Jos A E Spaan
- Department of Biomedical Engineering & Physics, Academic Medical Centre, Amsterdam, The Netherlands
| | - Eike Nagel
- Division of Imaging Sciences and Biomedical Engineering, King's College London, British Heart Foundation (BHF) Centre of Excellence, UK; National Institute of Heath Research (NIHR) Biomedical Research Centre at Guy's and St. Thomas' NHS Foundation Trust, Lambeth Wing, St. Thomas' Hospital, UK; Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC) Medical Engineering Centre, Lambeth Wing, St. Thomas' Hospital, London, UK
| | - Nicolas P Smith
- Division of Imaging Sciences and Biomedical Engineering, King's College London, British Heart Foundation (BHF) Centre of Excellence, UK; National Institute of Heath Research (NIHR) Biomedical Research Centre at Guy's and St. Thomas' NHS Foundation Trust, Lambeth Wing, St. Thomas' Hospital, UK; Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC) Medical Engineering Centre, Lambeth Wing, St. Thomas' Hospital, London, UK; Department of Engineering, University of Auckland, Auckland, New Zealand.
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8
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A perfusion procedure for imaging of the mouse cerebral vasculature by X-ray micro-CT. J Neurosci Methods 2013; 221:70-7. [PMID: 24056228 DOI: 10.1016/j.jneumeth.2013.09.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 08/26/2013] [Accepted: 09/02/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND Micro-CT is a novel X-ray imaging modality which can provide 3D high resolution images of the vascular network filled with contrast agent. The cerebrovascular system is a complex anatomical structure that can be imaged with contrast enhanced micro-CT. However, the morphology of the cerebrovasculature and many circulatory anastomosis in the brain result in high variations in the extent of contrast agent filling in the blood vessels and as a result, the vasculature of different subjects appear differently in the acquired images. Specifically, the posterior circulation is not consistently perfused with the contrast agent in many brain specimens and thus, many major vessels that perfuse blood to the midbrain and hindbrain are not visible in the micro-CT images acquired from these samples. NEW METHOD In this paper, we present a modified surgical procedure of cerebral vasculature perfusion through the left ventricle with Microfil contrast agent, in order to achieve a more uniform perfusion of blood vessels throughout the brain and as a result, more consistent images of the cerebrovasculature. Our method consists of filling the posterior cerebral circulation with contrast agent, followed by the perfusion of the whole cerebrovasculature. RESULTS Our histological results show that over 90% of the vessels in the entire brain, including the cerebellum, were filled with contrast agent. COMPARISON WITH EXISTING METHOD Our results show that the new technique of sample perfusion decreases the variability of the posterior circulation in the cerebellum in micro-CT images by 6.9%. CONCLUSIONS This new technique of sample preparation improves the quality of cerebrovascular images.
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Kim E, Stamatelos S, Cebulla J, Bhujwalla ZM, Popel AS, Pathak AP. Multiscale imaging and computational modeling of blood flow in the tumor vasculature. Ann Biomed Eng 2012; 40:2425-41. [PMID: 22565817 DOI: 10.1007/s10439-012-0585-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 04/27/2012] [Indexed: 12/30/2022]
Abstract
The evolution in our understanding of tumor angiogenesis has been the result of pioneering imaging and computational modeling studies spanning the endothelial cell, microvasculature and tissue levels. Many of these primary data on the tumor vasculature are in the form of images from pre-clinical tumor models that provide a wealth of qualitative and quantitative information in many dimensions and across different spatial scales. However, until recently, the visualization of changes in the tumor vasculature across spatial scales remained a challenge due to a lack of techniques for integrating micro- and macroscopic imaging data. Furthermore, the paucity of three-dimensional (3-D) tumor vascular data in conjunction with the challenges in obtaining such data from patients presents a serious hurdle for the development and validation of predictive, multiscale computational models of tumor angiogenesis. In this review, we discuss the development of multiscale models of tumor angiogenesis, new imaging techniques capable of reproducing the 3-D tumor vascular architecture with high fidelity, and the emergence of "image-based models" of tumor blood flow and molecular transport. Collectively, these developments are helping us gain a fundamental understanding of the cellular and molecular regulation of tumor angiogenesis that will benefit the development of new cancer therapies. Eventually, we expect this exciting integration of multiscale imaging and mathematical modeling to have widespread application beyond the tumor vasculature to other diseases involving a pathological vasculature, such as stroke and spinal cord injury.
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Affiliation(s)
- Eugene Kim
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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10
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Kline TL, Zamir M, Ritman EL. Accuracy of microvascular measurements obtained from micro-CT images. Ann Biomed Eng 2010; 38:2851-64. [PMID: 20458628 DOI: 10.1007/s10439-010-0058-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
Abstract
Early changes in branching geometry of microvasculature and its associated impact on the perfusion distribution in diseases, especially those in which different branching generations are affected differently, require the ability to analyze intact vascular trees over a wide range of scales. Micro-CT offers an excellent framework to analyze the microvascular branching geometry. Such an analysis requires methods to be developed that can accurately characterize branching properties, such as branch diameter, length, branching angle, and branch interconnectivity of the microvasculature. The purpose of this article is to report the results of a study of two human intramyocardial coronary vascular tree casts in which the accuracy of micro-CT vascular imaging and its analysis are tested against measurements made through an optical microscope (used as the "gold-standard"). Methods related to image segmentation of the vascular lumen, vessel tree centerline extraction, individual branch segment measurement, and compensating for the non-ideal modulation transfer function of micro-CT scanners are presented. The extracted centerline accurately characterized the hierarchical structure of the vascular tree casts in terms of "parent-branch" relationships which allowed each interbranch segments' dimensions to be compared to the optical measurement method. The comparison results show a close to ideal 1:1 relationship for both length and diameter measurements made by the two methods. Combining the results from both specimens, the standard deviation of the difference between measurement methods was 19 microm for the measurement of interbranch segment diameters (ranging from 12 to 769 microm), and 172 microm for the measurement of interbranch segment lengths (ranging from 14 to 3252 microm). These results suggest that our micro-CT image analysis method can be used to characterize a vascular tree's hierarchical structure, and accurately measure interbranch segment lengths and diameters.
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Affiliation(s)
- Timothy L Kline
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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11
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Marxen M, Sled J, Henkelman R. Volume Ordering for Analysis and Modeling of Vascular Systems. Ann Biomed Eng 2008; 37:542-51. [DOI: 10.1007/s10439-008-9623-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 12/12/2008] [Indexed: 10/21/2022]
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12
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Rennie MY, Whiteley KJ, Kulandavelu S, Adamson SL, Sled JG. 3D visualisation and quantification by microcomputed tomography of late gestational changes in the arterial and venous feto-placental vasculature of the mouse. Placenta 2007; 28:833-40. [PMID: 17324457 DOI: 10.1016/j.placenta.2006.12.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 11/24/2006] [Accepted: 12/18/2006] [Indexed: 10/23/2022]
Abstract
This study evaluates microcomputed tomography (micro-CT) as a method to obtain quantitative three-dimensional (3D) information on the arterial and venous vasculature of the mouse placenta. Surface renderings at embryonic days (E) 13.5, 15.5, and 18.5 (full term) revealed that the arterial and venous vasculature branched within the chorionic plate whereas only the arterial vasculature deeply penetrated the placenta. Umbilical vessel diameters measured by micro-CT did not significantly differ from those measured non-invasively in vivo by ultrasound biomicroscopy. Variability in umbilical diameters, and surface area and volume measurements of arterial and venous vascular trees due to experimental error was low relative to biological variability, and significant inter-litter differences within gestational ages were detected. Furthermore, umbilical vessel diameter increased significantly and incrementally to an arterial diameter of 0.631+/-0.009 mm and a venous diameter of 0.690+/-0.018 mm at E18.5. Umbilical vein diameter was 3-9% greater than the artery, and both were significantly correlated with embryonic body weight (R> or =0.96). Surface area and volume were determined for vessels greater than the minimum resolvable diameter of 0.03 mm which therefore excluded capillaries. Arterial surface area and volume were unchanged from E13.5-15.5 but then more than doubled at E18.5 (to 170+/-13 mm(2) and 7.2+/-0.8mm(3), respectively). Venous surface areas and volumes changed similarly with development although surface areas were lower than their arterial counterparts. We conclude that micro-CT has sufficient accuracy and precision to quantify late gestational changes in the 3D structure of the arterial and venous vasculature of the mouse placenta.
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Affiliation(s)
- M Y Rennie
- Department of Medical Biophysics, University of Toronto and the Mouse Imaging Centre, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
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