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Bayat S, Wild J, Winkler T. Lung functional imaging. Breathe (Sheff) 2023; 19:220272. [PMID: 38020338 PMCID: PMC10644108 DOI: 10.1183/20734735.0272-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 10/08/2023] [Indexed: 12/01/2023] Open
Abstract
Pulmonary functional imaging modalities such as computed tomography, magnetic resonance imaging and nuclear imaging can quantitatively assess regional lung functional parameters and their distributions. These include ventilation, perfusion, gas exchange at the microvascular level and biomechanical properties, among other variables. This review describes the rationale, strengths and limitations of the various imaging modalities employed for lung functional imaging. It also aims to explain some of the most commonly measured parameters of regional lung function. A brief review of evidence on the role and utility of lung functional imaging in early diagnosis, accurate lung functional characterisation, disease phenotyping and advancing the understanding of disease mechanisms in major respiratory disorders is provided.
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Affiliation(s)
- Sam Bayat
- Department of Pulmonology and Physiology, CHU Grenoble Alpes, Grenoble, France
- Univ. Grenoble Alpes, STROBE Laboratory, INSERM UA07, Grenoble, France
| | - Jim Wild
- POLARIS, Imaging Group, Department of Infection Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
| | - Tilo Winkler
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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2
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Albers J, Wagner WL, Fiedler MO, Rothermel A, Wünnemann F, Di Lillo F, Dreossi D, Sodini N, Baratella E, Confalonieri M, Arfelli F, Kalenka A, Lotz J, Biederer J, Wielpütz MO, Kauczor HU, Alves F, Tromba G, Dullin C. High resolution propagation-based lung imaging at clinically relevant X-ray dose levels. Sci Rep 2023; 13:4788. [PMID: 36959233 PMCID: PMC10036329 DOI: 10.1038/s41598-023-30870-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/02/2023] [Indexed: 03/25/2023] Open
Abstract
Absorption-based clinical computed tomography (CT) is the current imaging method of choice in the diagnosis of lung diseases. Many pulmonary diseases are affecting microscopic structures of the lung, such as terminal bronchi, alveolar spaces, sublobular blood vessels or the pulmonary interstitial tissue. As spatial resolution in CT is limited by the clinically acceptable applied X-ray dose, a comprehensive diagnosis of conditions such as interstitial lung disease, idiopathic pulmonary fibrosis or the characterization of small pulmonary nodules is limited and may require additional validation by invasive lung biopsies. Propagation-based imaging (PBI) is a phase sensitive X-ray imaging technique capable of reaching high spatial resolutions at relatively low applied radiation dose levels. In this publication, we present technical refinements of PBI for the characterization of different artificial lung pathologies, mimicking clinically relevant patterns in ventilated fresh porcine lungs in a human-scale chest phantom. The combination of a very large propagation distance of 10.7 m and a photon counting detector with [Formula: see text] pixel size enabled high resolution PBI CT with significantly improved dose efficiency, measured by thermoluminescence detectors. Image quality was directly compared with state-of-the-art clinical CT. PBI with increased propagation distance was found to provide improved image quality at the same or even lower X-ray dose levels than clinical CT. By combining PBI with iodine k-edge subtraction imaging we further demonstrate that, the high quality of the calculated iodine concentration maps might be a potential tool for the analysis of lung perfusion in great detail. Our results indicate PBI to be of great value for accurate diagnosis of lung disease in patients as it allows to depict pathological lesions non-invasively at high resolution in 3D. This will especially benefit patients at high risk of complications from invasive lung biopsies such as in the setting of suspected idiopathic pulmonary fibrosis (IPF).
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Affiliation(s)
- Jonas Albers
- Department for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany
- Biological X-ray imaging, European Molecular Biology Laboratory, Hamburg Unit c/o DESY, Hamburg, Germany
| | - Willi L Wagner
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
| | - Mascha O Fiedler
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
- Department of Anaesthesiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Anne Rothermel
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
| | - Felix Wünnemann
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
| | | | - Diego Dreossi
- Elettra-Sincrotrone Trieste S.C.p.A., Trieste, Italy
| | - Nicola Sodini
- Elettra-Sincrotrone Trieste S.C.p.A., Trieste, Italy
| | - Elisa Baratella
- Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | | | - Fulvia Arfelli
- Department of Physics, University of Trieste and INFN, Trieste, Italy
| | - Armin Kalenka
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
- Department of Anaesthesiology and Intensive Care Medicine, District Hospital Bergstrasse, Heppenheim, Germany
- Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
| | - Joachim Lotz
- Department for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany
| | - Jürgen Biederer
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
- Faculty of Medicine, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
- Faculty of Medicine, University of Latvia, Riga, Latvia
| | - Mark O Wielpütz
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
| | - Hans-Ulrich Kauczor
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany
| | - Frauke Alves
- Department for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany
- Department for Haematology and Medical Oncology, University Medical Center Goettingen, Goettingen, Germany
- Translational Molecular Imaging, Max-Plank-Institute for Multidisciplinary Sciences, Goettingen, Germany
| | | | - Christian Dullin
- Department for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany.
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany.
- Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), University Heidelberg, Heidelberg, Germany.
- Translational Molecular Imaging, Max-Plank-Institute for Multidisciplinary Sciences, Goettingen, Germany.
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Ahookhosh K, Vanoirbeek J, Vande Velde G. Lung function measurements in preclinical research: What has been done and where is it headed? Front Physiol 2023; 14:1130096. [PMID: 37035677 PMCID: PMC10073442 DOI: 10.3389/fphys.2023.1130096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/10/2023] [Indexed: 04/11/2023] Open
Abstract
Due to the close interaction of lung morphology and functions, repeatable measurements of pulmonary function during longitudinal studies on lung pathophysiology and treatment efficacy have been a great area of interest for lung researchers. Spirometry, as a simple and quick procedure that depends on the maximal inspiration of the patient, is the most common lung function test in clinics that measures lung volumes against time. Similarly, in the preclinical area, plethysmography techniques offer lung functional parameters related to lung volumes. In the past few decades, many innovative techniques have been introduced for in vivo lung function measurements, while each one of these techniques has their own advantages and disadvantages. Before each experiment, depending on the sensitivity of the required pulmonary functional parameters, it should be decided whether an invasive or non-invasive approach is desired. On one hand, invasive techniques offer sensitive and specific readouts related to lung mechanics in anesthetized and tracheotomized animals at endpoints. On the other hand, non-invasive techniques allow repeatable lung function measurements in conscious, free-breathing animals with readouts related to the lung volumes. The biggest disadvantage of these standard techniques for lung function measurements is considering the lung as a single unit and providing only global readouts. However, recent advances in lung imaging modalities such as x-ray computed tomography and magnetic resonance imaging opened new doors toward obtaining both anatomical and functional information from the same scan session, without the requirement for any extra pulmonary functional measurements, in more regional and non-invasive manners. Consequently, a new field of study called pulmonary functional imaging was born which focuses on introducing new techniques for regional quantification of lung function non-invasively using imaging-based techniques. This narrative review provides first an overview of both invasive and non-invasive conventional methods for lung function measurements, mostly focused on small animals for preclinical research, including discussions about their advantages and disadvantages. Then, we focus on those newly developed, non-invasive, imaging-based techniques that can provide either global or regional lung functional readouts at multiple time-points.
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Affiliation(s)
- Kaveh Ahookhosh
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Jeroen Vanoirbeek
- Centre of Environment and Health, Department of Public Health and Primary Care, KU Leuven, Leuven, Belgium
| | - Greetje Vande Velde
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- *Correspondence: Greetje Vande Velde,
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Bazin D, Lucas IT, Rouzière S, Elkaim E, Mocuta C, Réguer S, Reid DG, Mathurin J, Dazzi A, Deniset-Besseau A, Petay M, Frochot V, Haymann JP, Letavernier E, Verpont MC, Foy E, Bouderlique E, Colboc H, Daudon M. Profile of an “at cutting edge” pathology laboratory for pathological human deposits: from nanometer to in vivo scale analysis on large scale facilities. CR CHIM 2022. [DOI: 10.5802/crchim.199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Bayat S, Fardin L, Cercos-Pita JL, Perchiazzi G, Bravin A. Imaging Regional Lung Structure and Function in Small Animals Using Synchrotron Radiation Phase-Contrast and K-Edge Subtraction Computed Tomography. Front Physiol 2022; 13:825433. [PMID: 35350681 PMCID: PMC8957951 DOI: 10.3389/fphys.2022.825433] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
Synchrotron radiation offers unique properties of coherence, utilized in phase-contrast imaging, and high flux as well as a wide energy spectrum which allow the selection of very narrow energy bands of radiation, used in K-edge subtraction imaging (KES) imaging. These properties extend X-ray computed tomography (CT) capabilities to quantitatively assess lung morphology, and to map regional lung ventilation, perfusion, inflammation, aerosol particle distribution and biomechanical properties, with microscopic spatial resolution. Four-dimensional imaging, allows the investigation of the dynamics of regional lung functional parameters simultaneously with structural deformation of the lung as a function of time. These techniques have proven to be very useful for revealing the regional differences in both lung structure and function which is crucial for better understanding of disease mechanisms as well as for evaluating treatment in small animal models of lung diseases. Here, synchrotron radiation imaging methods are described and examples of their application to the study of disease mechanisms in preclinical animal models are presented.
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Affiliation(s)
- Sam Bayat
- Univ. Grenoble Alpes, Inserm UA07 STROBE Laboratory, University of Grenoble Alpes, Grenoble, France.,Department of Pulmonology and Clinical Physiology, Grenoble University Hospital, Grenoble, France
| | - Luca Fardin
- European Synchrotron Radiation Facility, Grenoble, France
| | - José Luis Cercos-Pita
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Gaetano Perchiazzi
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Alberto Bravin
- Department of Physics, University of Milano-Bicocca, Milan, Italy
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6
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Bayat S, Broche L, Dégrugilliers L, Porra L, Paiva M, Verbanck S. Fractal analysis reveals functional unit of ventilation in the lung. J Physiol 2021; 599:5121-5132. [PMID: 34647325 DOI: 10.1113/jp282093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/06/2021] [Indexed: 12/14/2022] Open
Abstract
Ventilation is inhomogeneous in the lungs across species. It has been hypothesized that ventilation inhomogeneity is largely determined by the design of the airway branching network. Because exchange of gases at the alveolar barrier is more efficient when gas concentrations are evenly distributed at subacinar length scales, it is assumed that a 'functional unit' of ventilation exists within the lung periphery, where gas concentration becomes uniform. On the other hand, because the morphology of pulmonary airways and alveoli, and the distribution of inhaled fluorescent particles show self-similar fractal properties over a wide range of length scales, it has been predicted that fractal dimension of ventilation approaches unity within an internally homogeneous functional unit of ventilation. However, the existence of such a functional unit has never been demonstrated experimentally due to lack of in situ gas concentration measurements of sufficient spatial resolution in the periphery of a complex bifurcating network. Here, using energy-subtractive synchrotron radiation tomography, we measured the distribution of an inert gas (Xe) in the in vivo rabbit lung during Xe wash-in breathing manoeuvres. The effects of convective flow rate, diffusion and cardiac motion were also assessed. Fractal analysis of resulting gas concentration and tissue density maps revealed that fractal dimension was always smaller for Xe than for tissue density, and that only for the gas, a length scale existed where fractal dimension approached unity. The length scale where this occurred was seen to correspond to that of a rabbit acinus, the terminal structure comprising only alveolated airways. KEY POINTS: Gas ventilation is inhomogeneous in the lung of many species. However, it is not known down to what length scales this inhomogeneity persists. It is generally assumed that ventilation becomes homogeneous at subacinar length scales, beyond the spatial resolution of commonly available imaging techniques, hence this has not been demonstrated experimentally. Here we measured the distribution of inhaled Xe gas in the rabbit lung using synchrotron radiation energy-subtractive imaging and used fractal analysis to show that ventilation becomes internally uniform within regions about the size of rabbit lung acini.
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Affiliation(s)
- Sam Bayat
- Department of Pulmonology and Physiology, Grenoble University Hospital, Grenoble, France.,Univ. Grenoble Alpes, STROBE Laboratory Inserm UA07, Grenoble, France
| | - Ludovic Broche
- Biomedical Beamline, European Synchrotron Radiation Facility, Grenoble, France
| | - Loïc Dégrugilliers
- Department of Paediatric Intensive Care, Amiens University Hospital, Amiens, France
| | - Liisa Porra
- Department of Physics, University of Helsinki, Helsinki University Central Hospital, Helsinki, Finland
| | - Manuel Paiva
- University Hospital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Sylvia Verbanck
- Respiratory Division, University Hospital UZ Brussel, Vrije Universiteit Brussel, Brussels, Belguim
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7
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Fardin L, Broche L, Lovric G, Mittone A, Stephanov O, Larsson A, Bravin A, Bayat S. Imaging atelectrauma in Ventilator-Induced Lung Injury using 4D X-ray microscopy. Sci Rep 2021; 11:4236. [PMID: 33608569 PMCID: PMC7895928 DOI: 10.1038/s41598-020-77300-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/04/2020] [Indexed: 02/07/2023] Open
Abstract
Mechanical ventilation can damage the lungs, a condition called Ventilator-Induced Lung Injury (VILI). However, the mechanisms leading to VILI at the microscopic scale remain poorly understood. Here we investigated the within-tidal dynamics of cyclic recruitment/derecruitment (R/D) using synchrotron radiation phase-contrast imaging (PCI), and the relation between R/D and cell infiltration, in a model of Acute Respiratory Distress Syndrome in 6 anaesthetized and mechanically ventilated New-Zealand White rabbits. Dynamic PCI was performed at 22.6 µm voxel size, under protective mechanical ventilation [tidal volume: 6 ml/kg; positive end-expiratory pressure (PEEP): 5 cmH2O]. Videos and quantitative maps of within-tidal R/D showed that injury propagated outwards from non-aerated regions towards adjacent regions where cyclic R/D was present. R/D of peripheral airspaces was both pressure and time-dependent, occurring throughout the respiratory cycle with significant scatter of opening/closing pressures. There was a significant association between R/D and regional lung cellular infiltration (p = 0.04) suggesting that tidal R/D of the lung parenchyma may contribute to regional lung inflammation or capillary-alveolar barrier dysfunction and to the progression of lung injury. PEEP may not fully mitigate this phenomenon even at high levels. Ventilation strategies utilizing the time-dependence of R/D may be helpful in reducing R/D and associated injury.
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Affiliation(s)
- Luca Fardin
- European Synchrotron Radiation Facility, Grenoble, France.,Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.,Synchrotron Radiation for Biomedicine Laboratory (STROBE, INSERM UA7), Grenoble, France
| | - Ludovic Broche
- European Synchrotron Radiation Facility, Grenoble, France
| | - Goran Lovric
- Center for Biomedical Imaging, EPFL, Lausanne, Switzerland.,Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | | | - Olivier Stephanov
- Department of Pathology, Grenoble University Hospital, Grenoble, France
| | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Alberto Bravin
- European Synchrotron Radiation Facility, Grenoble, France.,Synchrotron Radiation for Biomedicine Laboratory (STROBE, INSERM UA7), Grenoble, France
| | - Sam Bayat
- Synchrotron Radiation for Biomedicine Laboratory (STROBE, INSERM UA7), Grenoble, France. .,Department of Pulmonology and Physiology, Grenoble University Hospital, Bd. Du Maquis du Grésivaudan, 38700, La Tronche, France.
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Kulpe S, Dierolf M, Günther B, Brantl J, Busse M, Achterhold K, Pfeiffer F, Pfeiffer D. Spectroscopic imaging at compact inverse Compton X-ray sources. Phys Med 2020; 79:137-144. [PMID: 33271418 DOI: 10.1016/j.ejmp.2020.11.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/22/2020] [Accepted: 11/07/2020] [Indexed: 10/22/2022] Open
Abstract
While K-edge subtraction (KES) imaging is a commonly applied technique at synchrotron sources, the application of this imaging method in clinical imaging is limited although results have shown its superiority to conventional clinical subtraction imaging. Over the past decades, compact synchrotron X-ray sources, based on inverse Compton scattering, have been developed to fill the gap between conventional X-ray tubes and synchrotron facilities. These so called inverse Compton sources (ICSs) provide a tunable, quasi-monochromatic X-ray beam in a laboratory setting with reduced spatial and financial requirements. This allows for the transfer of imaging techniques that have been limited to synchrotrons until now, like KES imaging, into a laboratory environment. This review article presents the first studies that have successfully performed KES at ICSs. These have shown that KES provides improved image quality in comparison to conventional X-ray imaging. The results indicate that medical imaging could benefit from monochromatic imaging and KES techniques. Currently, the clinical application of KES is limited by the low K-edge energy of available iodine contrast agents. However, several ICSs are under development or already in commissioning which will provide monochromatic X-ray beams with higher X-ray energies and will enable KES using high-Z elements as contrast media. With these developments, KES at an ICS has the ability to become an important tool in pre-clinical research and potentially advancing existing clinical imaging techniques.
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Affiliation(s)
- Stephanie Kulpe
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany.
| | - Martin Dierolf
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Benedikt Günther
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Johannes Brantl
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Madleen Busse
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Klaus Achterhold
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Franz Pfeiffer
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany; Department of Diagnostic and Interventional Radiology, Munich School of Medicine and Klinikum rechts der Isar, Ismaniger Str. 22, 81675 Munich, Germany
| | - Daniela Pfeiffer
- Department of Diagnostic and Interventional Radiology, Munich School of Medicine and Klinikum rechts der Isar, Ismaniger Str. 22, 81675 Munich, Germany
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Functional lung imaging with synchrotron radiation: Methods and preclinical applications. Phys Med 2020; 79:22-35. [PMID: 33070047 DOI: 10.1016/j.ejmp.2020.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/30/2020] [Accepted: 10/03/2020] [Indexed: 01/05/2023] Open
Abstract
Many lung disease processes are characterized by structural and functional heterogeneity that is not directly appreciable with traditional physiological measurements. Experimental methods and lung function modeling to study regional lung function are crucial for better understanding of disease mechanisms and for targeting treatment. Synchrotron radiation offers useful properties to this end: coherence, utilized in phase-contrast imaging, and high flux and a wide energy spectrum which allow the selection of very narrow energy bands of radiation, thus allowing imaging at very specific energies. K-edge subtraction imaging (KES) has thus been developed at synchrotrons for both human and small animal imaging. The unique properties of synchrotron radiation extend X-ray computed tomography (CT) capabilities to quantitatively assess lung morphology, and also to map regional lung ventilation, perfusion, inflammation and biomechanical properties, with microscopic spatial resolution. Four-dimensional imaging, allows the investigation of the dynamics of regional lung functional parameters simultaneously with structural deformation of the lung as a function of time. This review summarizes synchrotron radiation imaging methods and overviews examples of its application in the study of disease mechanisms in preclinical animal models, as well as the potential for clinical translation both through the knowledge gained using these techniques and transfer of imaging technology to laboratory X-ray sources.
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10
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BriXS, a new X-ray inverse Compton source for medical applications. Phys Med 2020; 77:127-137. [PMID: 32829101 DOI: 10.1016/j.ejmp.2020.08.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 08/03/2020] [Accepted: 08/11/2020] [Indexed: 12/14/2022] Open
Abstract
MariX is a research infrastructure conceived for multi-disciplinary studies, based on a cutting-edge system of combined electron accelerators at the forefront of the world-wide scenario of X-ray sources. The generation of X-rays over a large photon energy range will be enabled by two unique X-ray sources: a Free Electron Laser and an inverse Compton source, called BriXS (Bright compact X-ray Source). The X-ray beam provided by BriXS is expected to have an average energy tunable in the range 20-180 keV and intensities between 1011 and 1013 photon/s within a relative bandwidth ΔE/E=1-10%. These characteristics, together with a very small source size (~20 μm) and a good transverse coherence, will enable a wide range of applications in the bio-medical field. An additional unique feature of BriXS will be the possibility to make a quick switch of the X-ray energy between two values for dual-energy and K-edge subtraction imaging. In this paper, the expected characteristics of BriXS will be presented, with a particular focus on the features of interest to its possible medical applications.
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11
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Cereda M, Xin Y, Goffi A, Herrmann J, Kaczka DW, Kavanagh BP, Perchiazzi G, Yoshida T, Rizi RR. Imaging the Injured Lung: Mechanisms of Action and Clinical Use. Anesthesiology 2019; 131:716-749. [PMID: 30664057 PMCID: PMC6692186 DOI: 10.1097/aln.0000000000002583] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Acute respiratory distress syndrome (ARDS) consists of acute hypoxemic respiratory failure characterized by massive and heterogeneously distributed loss of lung aeration caused by diffuse inflammation and edema present in interstitial and alveolar spaces. It is defined by consensus criteria, which include diffuse infiltrates on chest imaging-either plain radiography or computed tomography. This review will summarize how imaging sciences can inform modern respiratory management of ARDS and continue to increase the understanding of the acutely injured lung. This review also describes newer imaging methodologies that are likely to inform future clinical decision-making and potentially improve outcome. For each imaging modality, this review systematically describes the underlying principles, technology involved, measurements obtained, insights gained by the technique, emerging approaches, limitations, and future developments. Finally, integrated approaches are considered whereby multimodal imaging may impact management of ARDS.
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Affiliation(s)
- Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Alberto Goffi
- Interdepartmental Division of Critical Care Medicine and Department of Medicine, University of Toronto, ON, Canada
| | - Jacob Herrmann
- Departments of Anesthesia and Biomedical Engineering, University of Iowa, IA
| | - David W. Kaczka
- Departments of Anesthesia, Radiology, and Biomedical Engineering, University of Iowa, IA
| | | | - Gaetano Perchiazzi
- Hedenstierna Laboratory and Uppsala University Hospital, Uppsala University, Sweden
| | - Takeshi Yoshida
- Hospital for Sick Children, University of Toronto, ON, Canada
| | - Rahim R. Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
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12
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Gradl R, Dierolf M, Yang L, Hehn L, Günther B, Möller W, Kutschke D, Stoeger T, Gleich B, Achterhold K, Donnelley M, Pfeiffer F, Schmid O, Morgan KS. Visualizing treatment delivery and deposition in mouse lungs using in vivo x-ray imaging. J Control Release 2019; 307:282-291. [DOI: 10.1016/j.jconrel.2019.06.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 06/18/2019] [Accepted: 06/25/2019] [Indexed: 01/17/2023]
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13
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Schittny JC. How high resolution 3-dimensional imaging changes our understanding of postnatal lung development. Histochem Cell Biol 2018; 150:677-691. [PMID: 30390117 PMCID: PMC6267404 DOI: 10.1007/s00418-018-1749-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2018] [Indexed: 12/24/2022]
Abstract
During the last 10 + years biologically and clinically significant questions about postnatal lung development could be answered due to the application of modern cutting-edge microscopic and quantitative histological techniques. These are in particular synchrotron radiation based X-ray tomographic microscopy (SRXTM), but also 3Helium Magnetic Resonance Imaging, as well as the stereological estimation of the number of alveoli and the length of the free septal edge. First, the most important new finding may be the following: alveolarization of the lung does not cease after the maturation of the alveolar microvasculature but continues until young adulthood and, even more important, maybe reactivated lifelong if needed to rescue structural damages of the lungs. Second, the pulmonary acinus represents the functional unit of the lung. Because the borders of the acini could not be detected in classical histological sections, any investigation of the acini requires 3-dimensional (imaging) methods. Based on SRXTM it was shown that in rat lungs the number of acini stays constant, meaning that their volume increases by a factor of ~ 11 after birth. The latter is very important for acinar ventilation and particle deposition.
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Affiliation(s)
- Johannes C Schittny
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012, Bern, Switzerland.
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14
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Thomlinson W, Elleaume H, Porra L, Suortti P. K-edge subtraction synchrotron X-ray imaging in bio-medical research. Phys Med 2018; 49:58-76. [DOI: 10.1016/j.ejmp.2018.04.389] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/12/2018] [Accepted: 04/16/2018] [Indexed: 11/26/2022] Open
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15
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Porra L, Dégrugilliers L, Broche L, Albu G, Strengell S, Suhonen H, Fodor GH, Peták F, Suortti P, Habre W, Sovijärvi ARA, Bayat S. Quantitative Imaging of Regional Aerosol Deposition, Lung Ventilation and Morphology by Synchrotron Radiation CT. Sci Rep 2018; 8:3519. [PMID: 29476086 PMCID: PMC5824954 DOI: 10.1038/s41598-018-20986-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 01/29/2018] [Indexed: 01/02/2023] Open
Abstract
To understand the determinants of inhaled aerosol particle distribution and targeting in the lung, knowledge of regional deposition, lung morphology and regional ventilation, is crucial. No single imaging modality allows the acquisition of all such data together. Here we assessed the feasibility of dual-energy synchrotron radiation imaging to this end in anesthetized rabbits; both in normal lung (n = 6) and following methacholine (MCH)-induced bronchoconstriction (n = 6), a model of asthma. We used K-edge subtraction CT (KES) imaging to quantitatively map the regional deposition of iodine-containing aerosol particles. Morphological and regional ventilation images were obtained, followed by quantitative regional iodine deposition maps, after 5 and 10 minutes of aerosol administration. Iodine deposition was markedly inhomogeneous both in normal lung and after induced bronchoconstrition. Deposition was significantly reduced in the MCH group at both time points, with a strong dependency on inspiratory flow in both conditions (R2 = 0.71; p < 0.0001). We demonstrate for the first time, the feasibility of KES CT for quantitative imaging of lung deposition of aerosol particles, regional ventilation and morphology. Since these are among the main factors determining lung aerosol deposition, we expect this imaging approach to bring new contributions to the understanding of lung aerosol delivery, targeting, and ultimately biological efficacy.
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Affiliation(s)
- L Porra
- Department of Physics, University of Helsinki, Helsinki, Finland.,Helsinki University Central Hospital Medical Imaging Center, Helsinki, Finland
| | - L Dégrugilliers
- Department of Pediatric Intensive Care, Amiens University Hospital, Amiens, France
| | - L Broche
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - G Albu
- Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - S Strengell
- Department of Physics, University of Helsinki, Helsinki, Finland.,Helsinki University Central Hospital Medical Imaging Center, Helsinki, Finland
| | - H Suhonen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - G H Fodor
- Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - F Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - P Suortti
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - W Habre
- Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - A R A Sovijärvi
- Department of Clinical Physiology and Nuclear Medicine, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
| | - S Bayat
- University of Grenoble EA-7442 RSRM Laboratory and Department of Clinical Physiology, Sleep and Exercise, Grenoble University Hospital, Grenoble, France.
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16
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Lizal F, Jedelsky J, Morgan K, Bauer K, Llop J, Cossio U, Kassinos S, Verbanck S, Ruiz-Cabello J, Santos A, Koch E, Schnabel C. Experimental methods for flow and aerosol measurements in human airways and their replicas. Eur J Pharm Sci 2018; 113:95-131. [DOI: 10.1016/j.ejps.2017.08.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/14/2017] [Accepted: 08/17/2017] [Indexed: 12/29/2022]
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17
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Aulakh GK, Mann A, Belev G, Wiebe S, Kuebler WM, Singh B, Chapman D. Multiple image x-radiography for functional lung imaging. Phys Med Biol 2017; 63:015009. [PMID: 29116051 DOI: 10.1088/1361-6560/aa9904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Detection and visualization of lung tissue structures is impaired by predominance of air. However, by using synchrotron x-rays, refraction of x-rays at the interface of tissue and air can be utilized to generate contrast which may in turn enable quantification of lung optical properties. We utilized multiple image radiography, a variant of diffraction enhanced imaging, at the Canadian light source to quantify changes in unique x-ray optical properties of lungs, namely attenuation, refraction and ultra small-angle scatter (USAXS or width) contrast ratios as a function of lung orientation in free-breathing or respiratory-gated mice before and after intra-nasal bacterial endotoxin (lipopolysaccharide) instillation. The lung ultra small-angle scatter and attenuation contrast ratios were significantly higher 9 h post lipopolysaccharide instillation compared to saline treatment whereas the refraction contrast decreased in magnitude. In ventilated mice, end-expiratory pressures result in an increase in ultra small-angle scatter contrast ratio when compared to end-inspiratory pressures. There were no detectable changes in lung attenuation or refraction contrast ratio with change in lung pressure alone. In effect, multiple image radiography can be applied towards following optical properties of lung air-tissue barrier over time during pathologies such as acute lung injury.
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Affiliation(s)
- G K Aulakh
- Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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18
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Porra L, Broche L, Dégrugilliers L, Albu G, Malaspinas I, Doras C, Wallin M, Hallbäck M, Habre W, Bayat S. Synchrotron Imaging Shows Effect of Ventilator Settings on Intrabreath Cyclic Changes in Pulmonary Blood Volume. Am J Respir Cell Mol Biol 2017; 57:459-467. [PMID: 28535074 DOI: 10.1165/rcmb.2017-0007oc] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Despite the importance of dynamic changes in the regional distributions of gas and blood during the breathing cycle for lung function in the mechanically ventilated patient, no quantitative data on such cyclic changes are currently available. We used a novel gated synchrotron computed tomography imaging to quantitatively image regional lung gas volume (Vg), tissue density, and blood volume (Vb) in six anesthetized, paralyzed, and mechanically ventilated rabbits with normal lungs. Images were repeatedly collected during ventilation and steady-state inhalation of 50% xenon, or iodine infusion. Data were acquired in a dependent and nondependent image level, at zero end-expiratory pressure (ZEEP) and 9 cm H2O (positive end-expiratory pressure), and a tidal volume (Vt) of 6 ml/kg (Vt1) or 9 ml/kg (Vt2) at an Inspiratory:Expiratory ratio of 0.5 or 1.7 by applying an end-inspiratory pause. A video showing dynamic decreases in Vb during inspiration is presented. Vb decreased with positive end-expiratory pressure (P = 0.006; P = 0.036 versus Vt1-ZEEP and Vt2-ZEEP, respectively), and showed larger oscillations at the dependent image level, whereas a 45% increase in Vt did not have a significant effect. End-inspiratory Vb minima were reduced by an end-inspiratory pause (P = 0.042, P = 0.006 at nondependent and dependent levels, respectively). Normalized regional Vg:Vb ratio increased upon inspiration. Our data demonstrate, for the first time, within-tidal cyclic variations in regional pulmonary Vb. The quantitative matching of regional Vg and Vb improved upon inspiration under ZEEP. Further study is underway to determine whether these phenomena affect intratidal gas exchange.
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Affiliation(s)
- Liisa Porra
- 1 Department of Physics, University of Helsinki, Helsinki, Finland.,2 Medical Imaging Center, Helsinki University Hospital, Helsinki, Finland
| | - Ludovic Broche
- 3 Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Sweden
| | - Loïc Dégrugilliers
- 4 Department of Pediatric Intensive Care, Amiens University Hospital, Amiens, France
| | - Gergely Albu
- 5 Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Iliona Malaspinas
- 5 Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Camille Doras
- 5 Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | | | | | - Walid Habre
- 5 Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - Sam Bayat
- 5 Anesthesiological Investigations Unit, University Hospitals of Geneva, Geneva, Switzerland.,7 University of Grenoble EA-7442 and Department of Clinical Physiology, Sleep and Exercise, Grenoble University Hospital, Grenoble, France
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19
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Lovric G, Mokso R, Arcadu F, Vogiatzis Oikonomidis I, Schittny JC, Roth-Kleiner M, Stampanoni M. Tomographic in vivo microscopy for the study of lung physiology at the alveolar level. Sci Rep 2017; 7:12545. [PMID: 28970505 PMCID: PMC5624921 DOI: 10.1038/s41598-017-12886-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/14/2017] [Indexed: 01/27/2023] Open
Abstract
Lungs represent the essential part of the mammalian respiratory system, which is reflected in the fact that lung failure still is one of the leading causes of morbidity and mortality worldwide. Establishing the connection between macroscopic observations of inspiration and expiration and the processes taking place at the microscopic scale remains crucial to understand fundamental physiological and pathological processes. Here we demonstrate for the first time in vivo synchrotron-based tomographic imaging of lungs with pixel sizes down to a micrometer, enabling first insights into high-resolution lung structure. We report the methodological ability to study lung inflation patterns at the alveolar scale and its potential in resolving still open questions in lung physiology. As a first application, we identified heterogeneous distension patterns at the alveolar level and assessed first comparisons of lungs between the in vivo and immediate post mortem states.
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Affiliation(s)
- Goran Lovric
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland. .,Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland. .,Centre d'Imagerie BioMédicale, École Polytechnique Fédérale de Lausanne, Lausanne, 1015, Switzerland.
| | - Rajmund Mokso
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Max IV Laboratory, Lund University, SE-221 00, Lund, Sweden
| | - Filippo Arcadu
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland
| | - Ioannis Vogiatzis Oikonomidis
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute of Anatomy, University of Bern, 3012, Bern, Switzerland
| | | | - Matthias Roth-Kleiner
- Clinic of Neonatology, University Hospital of Lausanne (CHUV), 1011, Lausanne, Switzerland
| | - Marco Stampanoni
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland.,Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland
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Zhao Y, Wu Y, Zuo Z, Suo H, Zhao S, Han J, Chang X, Cheng S. Application of low concentration contrast medium in spectral CT imaging for CT portal venography. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2017; 25:135-143. [PMID: 27768006 DOI: 10.3233/xst-16188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
OBJECTIVE To investigate the effect of low-concentration contrast medium on spectral computed tomography (CT) image quality for portal venography CT. METHODS 150 patients with suspected portal diseases were divided into three groups and had spectral CT examination using a GE Discovery CT 750 HD scanner. The patients in three groups were injected with different concentrations of iodine (350 mgI/mL, 315 mgI/mL and 280 mgI/mL) at an injection rate of 4.0-5.0 mL/s with 1.2 mL/kg (body weight) of contrast medium, respectively. During the portal vein imaging phase, 0.625 mm-slice-thickness monochromatic images and optimal monochromatic images were obtained. Optimal keV mono-energy was achieved using the optimal contrast-to-noise ratio (CNR) in the portal vein relative to the erector spinae muscle. Volume rendering and maximum intensity projection methods were applied to generate portal venography. The CT values and standard deviations were measured at the portal vein, the erector spinae muscle, and the abdomen fat, respectively. These values were used to calculate the signal-to-noise ratio (SNR); while CNR was calculated using CT values of the portal vein and erector spinae muscle. The overall imaging quality was evaluated on a five-point scale by two radiologists with at least five years' experience. Comparisons among the three groups were performed using One-Way ANOVA test. RESULTS Monochromatic images at 50-53 keV demonstrated the best CNR for both the portal vein and erector spinae muscle. SNR and CNR of images with different contrast medium concentrations were similar (P > 0.05). The five-point scores were also similar (P > 0.05) for the three groups. The total iodine intake at 280 mgI/mL was 25.4% lower than that at 350 mgI/mL. CONCLUSIONS Spectral CT with monochromatic images at 50-53 keV allows significant reduction in iodine load while improving portal vein signal intensity and maintaining image quality.
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Affiliation(s)
- Yongxia Zhao
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
| | - Yanmin Wu
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
| | - Ziwei Zuo
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
| | - Hongna Suo
- Medicine School of Hebei University, Baoding, Hebei Province, China
| | - Sisi Zhao
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
| | - Jun Han
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
| | - Xian Chang
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
| | - Shujie Cheng
- The Affiliated Hospital of Hebei university, Baoding, Hebei Province, China
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21
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Pressure-regulated volume control vs. volume control ventilation in healthy and injured rabbit lung. Eur J Anaesthesiol 2016; 33:767-75. [DOI: 10.1097/eja.0000000000000485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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22
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Borges JB, Porra L, Pellegrini M, Tannoia A, Derosa S, Larsson A, Bayat S, Perchiazzi G, Hedenstierna G. Zero expiratory pressure and low oxygen concentration promote heterogeneity of regional ventilation and lung densities. Acta Anaesthesiol Scand 2016; 60:958-68. [PMID: 27000315 PMCID: PMC5071663 DOI: 10.1111/aas.12719] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 01/20/2016] [Accepted: 02/11/2016] [Indexed: 12/26/2022]
Abstract
Background It is not well known what is the main mechanism causing lung heterogeneity in healthy lungs under mechanical ventilation. We aimed to investigate the mechanisms causing heterogeneity of regional ventilation and parenchymal densities in healthy lungs under anesthesia and mechanical ventilation. Methods In a small animal model, synchrotron imaging was used to measure lung aeration and regional‐specific ventilation (sV̇). Heterogeneity of ventilation was calculated as the coefficient of variation in sV̇ (CVsV̇). The coefficient of variation in lung densities (CVD) was calculated for all lung tissue, and within hyperinflated, normally and poorly aerated areas. Three conditions were studied: zero end‐expiratory pressure (ZEEP) and FIO2 0.21; ZEEP and FIO2 1.0; PEEP 12 cmH2O and FIO21.0 (Open Lung‐PEEP = OLP). Results The mean tissue density at OLP was lower than ZEEP‐1.0 and ZEEP‐0.21. There were larger subregions with low sV̇ and poor aeration at ZEEP‐0.21 than at OLP: 12.9 ± 9.0 vs. 0.6 ± 0.4% in the non‐dependent level, and 17.5 ± 8.2 vs. 0.4 ± 0.1% in the dependent one (P = 0.041). The CVsV̇ of the total imaged lung at PEEP 12 cmH2O was significantly lower than on ZEEP, regardless of FIO2, indicating more heterogeneity of ventilation during ZEEP (0.23 ± 0.03 vs. 0.54 ± 0.37, P = 0.049). CVD changed over the different mechanical ventilation settings (P = 0.011); predominantly, CVD increased during ZEEP. The spatial distribution of the CVD calculated for the poorly aerated density category changed with the mechanical ventilation settings, increasing in the dependent level during ZEEP. Conclusion ZEEP together with low FIO2 promoted heterogeneity of ventilation and lung tissue densities, fostering a greater amount of airway closure and ventilation inhomogeneities in poorly aerated regions.
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Affiliation(s)
- J. B. Borges
- Hedenstierna Laboratory Department of Surgical Sciences Section of Anaesthesiology & Critical Care Uppsala University Uppsala Sweden
- Pulmonary Divison Heart Institute (Incor) Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo Brazil
| | - L. Porra
- Department of Physics University of Helsinki Helsinki Finland
- Helsinki University Central Hospital Helsinki Finland
| | - M. Pellegrini
- Department of Emergency and Organ Transplant Bari University Italy
| | - A. Tannoia
- Department of Emergency and Organ Transplant Bari University Italy
| | - S. Derosa
- Department of Emergency and Organ Transplant Bari University Italy
| | - A. Larsson
- Hedenstierna Laboratory Department of Surgical Sciences Section of Anaesthesiology & Critical Care Uppsala University Uppsala Sweden
| | - S. Bayat
- Inserm UMR1105 and Pediatric Lung Function Laboratory CHU Amiens Université de Picardie Jules Verne Amiens France
| | - G. Perchiazzi
- Hedenstierna Laboratory Department of Surgical Sciences Section of Anaesthesiology & Critical Care Uppsala University Uppsala Sweden
- Department of Emergency and Organ Transplant Bari University Italy
| | - G. Hedenstierna
- Hedenstierna Laboratory Department of Medical Sciences Clinical Physiology Uppsala University Uppsala Sweden
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23
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Afshar S, Shamsai A, Saghafian B. Dam sediment tracking using spectrometry and Landsat 8 satellite image, Taleghan Basin, Iran. ENVIRONMENTAL MONITORING AND ASSESSMENT 2016; 188:104. [PMID: 26790431 DOI: 10.1007/s10661-015-5052-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 12/10/2015] [Indexed: 06/05/2023]
Abstract
Sedimentation in reservoirs, in addition to reducing water storage capacity, causes serious environmental impacts including intensification of river erosion. Detection of sediment origins plays a determining role in control and prevention of sedimentation. Nowadays, with the help of studies on sedimentation and erosion, sediment origins can be detected with high accuracy. This research integrated geographic information system (GIS) and remote sensing (RS) techniques to detect the primary source of sediment to Taleghan Dam in northern Iran. After collecting samples of sediment from the basin outlet, they were divided into two parts. One part was sent to the Mineralogy Laboratory in order to determine the percentage of each mineral in the samples using X-ray. A few were sent to the Spectroscopy Laboratory to determine their spectral signature using the spectrometer. The laboratory test results determined the wavelength of the minerals. In the next step, those spots on the satellite image whose spectral reflectance fell within the spectral signature of the minerals were detected and enhanced by mixture-tuned matched filtering (MTMF) method. These spots were overlapped with the map of geological formations. Accordingly, the origin of the minerals was detected. The greatest proportion of trace minerals was found in sample 4 including 6% of Illite trace mineral, while sample 2 contains only 2% of trace minerals. Accordingly, the origin of the minerals was detected. The obtained results revealed that mudstone, red siltstone, and conglomerate formations, Karaj formation in section Poldokhtar, acidic tuffs, alcanic lavas of Karaj Formation, mudstone and gypsum of upper red formation, and Cambrian dolomites were recognized as the most possible origins of the dam sediments. These formations are vulnerable to erosion and should be conserved so as to substantially prevent the volume of sedimentation in the reservoir.
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Affiliation(s)
- Sirous Afshar
- Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
| | - Abolfazl Shamsai
- Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Bahram Saghafian
- Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
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Bayat S, Porra L, Broche L, Albu G, Malaspinas I, Doras C, Strengell S, Peták F, Habre W. Effect of surfactant on regional lung function in an experimental model of respiratory distress syndrome in rabbit. J Appl Physiol (1985) 2015; 119:290-8. [DOI: 10.1152/japplphysiol.00047.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 05/14/2015] [Indexed: 11/22/2022] Open
Abstract
We assessed the changes in regional lung function following instillation of surfactant in a model of respiratory distress syndrome (RDS) induced by whole lung lavage and mechanical ventilation in eight anaesthetized, paralyzed, and mechanically ventilated New Zealand White rabbits. Regional specific ventilation (sV̇) was measured by K-edge subtraction synchrotron computed tomography during xenon washin. Lung regions were classified as poorly aerated (PA), normally aerated (NA), or hyperinflated (HI) based on regional density. A functional category was defined within each class based on sV̇ distribution (High, Normal, and Low). Airway resistance (Raw), respiratory tissue damping (G), and elastance (H) were measured by forced oscillation technique at low frequencies before and after whole lung saline lavage-induced (100 ml/kg) RDS, and 5 and 45 min after intratracheal instillation of beractant (75 mg/kg). Surfactant instillation improved Raw, G, and H ( P < 0.05 each), and gas exchange and decreased atelectasis ( P < 0.001). It also significantly improved lung aeration and ventilation in atelectatic lung regions. However, in regions that had remained normally aerated after lavage, it decreased regional aeration and increased sV̇ ( P < 0.001) and sV̇ heterogeneity. Although surfactant treatment improved both central airway and tissue mechanics and improved regional lung function of initially poorly aerated and atelectatic lung, it deteriorated regional lung function when local aeration was normal prior to administration. Local mechanical and functional heterogeneity can potentially contribute to the worsening of RDS and gas exchange. These data underscore the need for reassessing the benefits of routine prophylactic vs. continuous positive airway pressure and early “rescue” surfactant therapy in very immature infants.
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Affiliation(s)
- Sam Bayat
- Université de Picardie Jules Verne, Inserm U1105 and Pediatric Lung Function Laboratory, Amiens University Hospital, Amiens, France
| | - Liisa Porra
- Department of Physics, University of Helsinki, and Helsinki University Central Hospital, Helsinki, Finland
| | - Ludovic Broche
- Université de Picardie Jules Verne, Inserm U1105 and Pediatric Lung Function Laboratory, Amiens University Hospital, Amiens, France
- European Synchrotron Radiation Facility, Biomedical Beamline-ID17, Grenoble, France
| | - Gergely Albu
- Anesthesiological Investigation Unit, University of Geneva, Geneva, Switzerland
| | - Iliona Malaspinas
- Anesthesiological Investigation Unit, University of Geneva, Geneva, Switzerland
| | - Camille Doras
- Anesthesiological Investigation Unit, University of Geneva, Geneva, Switzerland
| | - Satu Strengell
- Department of Physics, University of Helsinki, and Helsinki University Central Hospital, Helsinki, Finland
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary; and
| | - Walid Habre
- Anesthesiological Investigation Unit, University of Geneva, Geneva, Switzerland
- Geneva Children's Hospital, University Hospitals of Geneva and Geneva University, Geneva, Switzerland
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25
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Mokso R, Oberta P. Simultaneous dual-energy X-ray stereo imaging. JOURNAL OF SYNCHROTRON RADIATION 2015; 22:1078-1082. [PMID: 26134814 PMCID: PMC4787031 DOI: 10.1107/s1600577515006554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 03/31/2015] [Indexed: 06/04/2023]
Abstract
Dual-energy or K-edge imaging is used to enhance contrast between two or more materials in an object and is routinely realised by acquiring two separate X-ray images each at different X-ray wavelength. On a broadband synchrotron source an imaging system to acquire the two images simultaneously was realised. The single-shot approach allows dual-energy and stereo imaging to be applied to dynamic systems. Using a Laue-Bragg crystal splitting scheme, the X-ray beam was split into two and the two beam branches could be easily tuned to either the same or to two different wavelengths. Due to the crystals' mutual position, the two beam branches intercept each other under a non-zero angle and create a stereoscopic setup.
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Affiliation(s)
- Rajmund Mokso
- Paul Scherrer Institute, Swiss Light Source, CH 5232 Villigen, Switzerland
| | - Peter Oberta
- Institute of Physics of the Academy of Sciences of the Czech Republic, v.v.i., Na Slovance 1999/2, Praha 8, Czech Republic
- Rigaku Innovative Technologies Europe s.r.o., Novodvorska 994, Praha 4, Czech Republic
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26
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Strengell S, Keyriläinen J, Suortti P, Bayat S, Sovijärvi ARA, Porra L. Radiation dose and image quality in K-edge subtraction computed tomography of lung in vivo. JOURNAL OF SYNCHROTRON RADIATION 2014; 21:1305-1313. [PMID: 25343799 DOI: 10.1107/s160057751401697x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/23/2014] [Indexed: 06/04/2023]
Abstract
K-edge subtraction computed tomography (KES-CT) allows simultaneous imaging of both structural features and regional distribution of contrast elements inside an organ. Using this technique, regional lung ventilation and blood volume distributions can be measured experimentally in vivo. In order for this imaging technology to be applicable in humans, it is crucial to minimize exposure to ionizing radiation with little compromise in image quality. The goal of this study was to assess the changes in signal-to-noise ratio (SNR) of KES-CT lung images as a function of radiation dose. The experiments were performed in anesthetized and ventilated rabbits using inhaled xenon gas in O2 at two concentrations: 20% and 70%. Radiation dose, defined as air kerma (Ka), was measured free-in-air and in a 16 cm polymethyl methacrylate phantom with a cylindrical ionization chamber. The dose free-in-air was varied from 2.7 mGy to 8.0 Gy. SNR in the images of xenon in air spaces was above the Rose criterion (SNR > 5) when Ka was over 400 mGy with 20% xenon, and over 40 mGy with 70% xenon. Although in human thorax attenuation is higher, based on these findings it is estimated that, by optimizing the imaging sequence and reconstruction algorithms, the radiation dose could be further reduced to clinically acceptable levels.
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Affiliation(s)
- S Strengell
- Department of Physics, University of Helsinki, Helsinki 00370, Finland
| | - J Keyriläinen
- Department of Oncology, Helsinki University Central Hospital, Helsinki, Finland
| | - P Suortti
- Department of Physics, University of Helsinki, Helsinki 00370, Finland
| | - S Bayat
- Université de Picardie Jules Verne, Inserm U1105 and CHU Amiens, France
| | - A R A Sovijärvi
- Department of Clinical Physiology and Nuclear Medicine, Helsinki University Central Hospital, Helsinki, Finland
| | - L Porra
- Department of Physics, University of Helsinki, Helsinki 00370, Finland
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Olubamiji AD, Izadifar Z, Chen DX. Synchrotron Imaging Techniques for Bone and Cartilage Tissue Engineering: Potential, Current Trends, and Future Directions. TISSUE ENGINEERING PART B-REVIEWS 2014; 20:503-22. [DOI: 10.1089/ten.teb.2013.0493] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
| | - Zohreh Izadifar
- Division of Biomedical Engineering, University of Saskatchewan, Saskatoon, Canada
| | - Daniel Xiongbiao Chen
- Division of Biomedical Engineering, University of Saskatchewan, Saskatoon, Canada
- Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Canada
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Murrie RP, Stevenson AW, Morgan KS, Fouras A, Paganin DM, Siu KKW. Feasibility study of propagation-based phase-contrast X-ray lung imaging on the Imaging and Medical beamline at the Australian Synchrotron. JOURNAL OF SYNCHROTRON RADIATION 2014; 21:430-445. [PMID: 24562566 DOI: 10.1107/s1600577513034681] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/27/2013] [Indexed: 06/03/2023]
Abstract
Propagation-based phase-contrast X-ray imaging (PB-PCXI) using synchrotron radiation has achieved high-resolution imaging of the lungs of small animals both in real time and in vivo. Current studies are applying such imaging techniques to lung disease models to aid in diagnosis and treatment development. At the Australian Synchrotron, the Imaging and Medical beamline (IMBL) is well equipped for PB-PCXI, combining high flux and coherence with a beam size sufficient to image large animals, such as sheep, due to a wiggler source and source-to-sample distances of over 137 m. This study aimed to measure the capabilities of PB-PCXI on IMBL for imaging small animal lungs to study lung disease. The feasibility of combining this technique with computed tomography for three-dimensional imaging and X-ray velocimetry for studies of airflow and non-invasive lung function testing was also investigated. Detailed analysis of the role of the effective source size and sample-to-detector distance on lung image contrast was undertaken as well as phase retrieval for sample volume analysis. Results showed that PB-PCXI of lung phantoms and mouse lungs produced high-contrast images, with successful computed tomography and velocimetry also being carried out, suggesting that live animal lung imaging will also be feasible at the IMBL.
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Affiliation(s)
| | - Andrew W Stevenson
- CSIRO Materials Science and Engineering, Private Bag 33, Clayton South, Victoria 3169, Australia
| | - Kaye S Morgan
- School of Physics, Monash University, Victoria 3800, Australia
| | - Andreas Fouras
- Department of Mechanical and Aerospace Engineering, Monash University, Victoria 3800, Australia
| | - David M Paganin
- School of Physics, Monash University, Victoria 3800, Australia
| | - Karen K W Siu
- School of Physics, Monash University, Victoria 3800, Australia
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Leong AFT, Paganin DM, Hooper SB, Siew ML, Kitchen MJ. Measurement of absolute regional lung air volumes from near-field x-ray speckles. OPTICS EXPRESS 2013; 21:27905-23. [PMID: 24514306 DOI: 10.1364/oe.21.027905] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Propagation-based phase contrast x-ray (PBX) imaging yields high contrast images of the lung where airways that overlap in projection coherently scatter the x-rays, giving rise to a speckled intensity due to interference effects. Our previous works have shown that total and regional changes in lung air volumes can be accurately measured from two-dimensional (2D) absorption or phase contrast images when the subject is immersed in a water-filled container. In this paper we demonstrate how the phase contrast speckle patterns can be used to directly measure absolute regional lung air volumes from 2D PBX images without the need for a water-filled container. We justify this technique analytically and via simulation using the transport-of-intensity equation and calibrate the technique using our existing methods for measuring lung air volume. Finally, we show the full capabilities of this technique for measuring regional differences in lung aeration.
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Bayat S, Porra L, Albu G, Suhonen H, Strengell S, Suortti P, Sovijärvi A, Peták F, Habre W. Effect of positive end-expiratory pressure on regional ventilation distribution during mechanical ventilation after surfactant depletion. Anesthesiology 2013; 119:89-100. [PMID: 23559029 DOI: 10.1097/aln.0b013e318291c165] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Ventilator-induced lung injury occurs due to exaggerated local stresses, repeated collapse, and opening of terminal air spaces in poorly aerated dependent lung, and increased stretch in nondependent lung. The aim of this study was to quantify the functional behavior of peripheral lung units in whole-lung lavage-induced surfactant depletion, and to assess the effect of positive end-expiratory pressure. METHODS The authors used synchrotron imaging to measure lung aeration and regional specific ventilation at positive end-expiratory pressure of 3 and 9 cm H2O, before and after whole-lung lavage in rabbits. Respiratory mechanical parameters were measured, and helium-washout was used to assess end-expiratory lung volume. RESULTS Atelectatic, poorly, normally aerated, hyperinflated, and trapped regions could be identified using the imaging technique used in this study. Surfactant depletion significantly increased atelectasis (6.3±3.3 [mean±SEM]% total lung area; P=0.04 vs. control) and poor aeration in dependent lung. Regional ventilation was distributed to poorly aerated regions with high (16.4±4.4%; P<0.001), normal (20.7±5.9%; P<0.001 vs. control), and low (5.7±1.2%; P<0.05 vs. control) specific ventilation. Significant redistribution of ventilation to normally aerated nondependent lung regions occurred (41.0±9.6%; P=0.03 vs. control). Increasing positive end-expiratory pressure level to 9 cm H2O significantly reduced poor aeration and recruited atelectasis, but ventilation redistribution persisted (39.2±9.5%; P<0.001 vs. control). CONCLUSIONS Ventilation of poorly aerated dependent lung regions, which can promote the local concentration of mechanical stresses, was the predominant functional behavior in surfactant-depleted lung. Potential tidal recruitment of atelectatic lung regions involved a smaller fraction of the imaged lung. Significant ventilation redistribution to aerated lung regions places these at risk of increased stretch injury.
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Affiliation(s)
- Sam Bayat
- Université de Picardie Jules Verne, EA4285 Péritox-INERIS and Pediatric Lung Function Laboratory, CHU Amiens, Amiens, France
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Strengell S, Porra L, Sovijärvi A, Suhonen H, Suortti P, Bayat S. Differences in the pattern of bronchoconstriction induced by intravenous and inhaled methacholine in rabbit. Respir Physiol Neurobiol 2013; 189:465-72. [PMID: 24012991 DOI: 10.1016/j.resp.2013.08.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 11/27/2022]
Abstract
We measured bronchoconstriction in central bronchi, and in small peripheral airways causing the emergence of ventilation defects (VD), through two delivery routes: intravenous (IV) and inhaled MCh, in 2 groups of rabbits (A: n=5; B: n=4), using synchrotron imaging of regional lung structure and ventilation. We assessed the effect an initial IV challenge on a subsequent inhaled challenge in group B. Inhaled MCh decreased central airway cross-sections (CA) by 13-22%, but increased VD area by 25-49%. IV MCh decreased CA by 44% but increased the area of ventilation defects (VD) by 13% only. An initial IV MCh challenge reduced regional ventilation heterogeneity following a subsequent inhaled MCh challenge, suggesting the role of agonist-receptor interaction in the response pattern. Heterogeneous agonist distribution due to uneven aerosol deposition could explain the different patterns of response between IV and inhaled routes. This mechanism could participate in the emergence of ventilation heterogeneities during bronchial challenge, or exposure to allergen in asthmatic patients.
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Lovric G, Barré SF, Schittny JC, Roth-Kleiner M, Stampanoni M, Mokso R. Dose optimization approach to fast X-ray microtomography of the lung alveoli. J Appl Crystallogr 2013; 46:856-860. [PMID: 24046488 PMCID: PMC3769076 DOI: 10.1107/s0021889813005591] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 02/26/2013] [Indexed: 01/10/2023] Open
Abstract
A basic prerequisite for in vivo X-ray imaging of the lung is the exact determination of radiation dose. Achieving resolutions of the order of micrometres may become particularly challenging owing to increased dose, which in the worst case can be lethal for the imaged animal model. A framework for linking image quality to radiation dose in order to optimize experimental parameters with respect to dose reduction is presented. The approach may find application for current and future in vivo studies to facilitate proper experiment planning and radiation risk assessment on the one hand and exploit imaging capabilities on the other.
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Affiliation(s)
- Goran Lovric
- Swiss Light Source, Paul Scherrer Institute, 5234 Villigen, Switzerland
- Institute for Biomedical Engineering, University and ETH Zurich, 8092 Zurich, Switzerland
| | - Sébastien F. Barré
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | | | - Matthias Roth-Kleiner
- Clinic of Neonatology, University Hospital of Lausanne (CHUV), 1011 Lausanne, Switzerland
| | - Marco Stampanoni
- Swiss Light Source, Paul Scherrer Institute, 5234 Villigen, Switzerland
- Institute for Biomedical Engineering, University and ETH Zurich, 8092 Zurich, Switzerland
| | - Rajmund Mokso
- Swiss Light Source, Paul Scherrer Institute, 5234 Villigen, Switzerland
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Layachi S, Porra L, Albu G, Trouillet N, Suhonen H, Peták F, Sevestre H, Suortti P, Sovijärvi A, Habre W, Bayat S. Role of cellular effectors in the emergence of ventilation defects during allergic bronchoconstriction. J Appl Physiol (1985) 2013; 115:1057-64. [PMID: 23887899 DOI: 10.1152/japplphysiol.00844.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is not known whether local factors within the airway wall or parenchyma may influence the emergence and spatial distribution of ventilation defects (VDs), thereby modulating the dynamic system behavior of the lung during bronchoconstriction. We assessed the relationship between the distribution of cellular effectors and the emergence of defects in regional ventilation distribution following allergen challenge. We performed high-resolution K-edge subtraction (KES) synchrotron imaging during xenon inhalation and measured the forced oscillatory input impedance in ovalbumin (OVA)-sensitized Brown-Norway rats (n = 12) at baseline and repeatedly following OVA challenge. Histological slices with best anatomic matching to the computed tomographic images were stained with a modified May-Grunwald Giemsa and immunohistochemical staining with monoclonal anti-rat CD68, in six rats. Slides were digitized and total cells and eosinophils were counted in the walls of bronchi and vessels randomly selected within and outside of VDs on the basis of xenon-KES images. Ventilated alveolar area decreased and ventilation heterogeneity, Newtonian resistance, tissue damping, and elastance increased following OVA challenge. Eosinophil, total cell, and CD68+ counts were significantly higher in the bronchial and vascular walls within vs. outside of the VDs. The minimal central airway diameters during OVA-induced bronchoconstriction were correlated with eosinophil (R = -0.85; P = 0.031) and total cell densities (R = -0.82; P = 0.046) in the airway walls within the poorly ventilated zones. Our findings suggest that allergic airway inflammation is locally heterogeneous and is topographically associated with the local emergence of VDs following allergen challenge.
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Affiliation(s)
- Skander Layachi
- Université de Picardie Jules Verne and Amiens University Hospital, Amiens, France
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Cooper DML, Chapman LD, Carter Y, Wu Y, Panahifar A, Britz HM, Bewer B, Zhouping W, Duke MJM, Doschak M. Three dimensional mapping of strontium in bone by dual energy K-edge subtraction imaging. Phys Med Biol 2012; 57:5777-86. [PMID: 22948244 DOI: 10.1088/0031-9155/57/18/5777] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The bones of many terrestrial vertebrates, including humans, are continually altered through an internal process of turnover known as remodeling. This process plays a central role in bone adaptation and disease. The uptake of fluorescent tetracyclines within bone mineral is widely exploited as a means of tracking new tissue formation. While investigation of bone microarchitecture has undergone a dimensional shift from 2D to 3D in recent years, we lack a 3D equivalent to fluorescent labeling. In the current study we demonstrate the ability of synchrotron radiation dual energy K-edge subtraction (KES) imaging to map the 3D distribution of elemental strontium within rat vertebral samples. This approach has great potential for ex vivo analysis of preclinical models and human tissue samples. KES also represents a powerful tool for investigating the pharmokinetics of strontium-based drugs recently approved in many countries around the globe for the treatment of osteoporosis.
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Affiliation(s)
- D M L Cooper
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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35
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Yuan R, Shuman WP, Earls JP, Hague CJ, Mumtaz HA, Scott-Moncrieff A, Ellis JD, Mayo JR, Leipsic JA. Reduced iodine load at CT pulmonary angiography with dual-energy monochromatic imaging: comparison with standard CT pulmonary angiography--a prospective randomized trial. Radiology 2011; 262:290-7. [PMID: 22084206 DOI: 10.1148/radiol.11110648] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To compare quantitative and subjective image quality and radiation dose between standard computed tomographic (CT) pulmonary angiography (CTPA) and CTPA with a dual-energy technique with reduced iodine load. MATERIALS AND METHODS This prospective study was approved by the institutional review board and each participant provided informed consent. Ninety-four patients (59% male; mean age ± standard deviation, 62 years ± 15) were randomized to one of two protocols: standard CTPA (100-120 kVp) with standard contrast medium injection (n = 46) and dual-energy CTPA (image reconstruction at 50 keV) with the same injection volume as in the standard protocol but composed of contrast medium and saline in a 1:1 fashion, resulting in 50% reduction in iodine load (n = 48). Signal intensity and noise in three central and two segmental pulmonary arteries were measured; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate vascular enhancement and image noise. The proportion of diagnostic (score, ≥ 3) studies and the interreader agreement regarding the dichotomized diagnostic versus nondiagnostic scale were compared between the two groups. RESULTS Compared with standard CTPA, dual-energy CTPA demonstrated higher signal intensity in all pulmonary arteries (all P < .01), inferior noise only in segmental arteries (P < .05), higher SNR and CNR (both P < .05), and compatible effective dose (P > .05). The five-point score was higher in the standard CTPA protocol (P < .05). The interreader agreement regarding the dichotomized diagnostic versus nondiagnostic scale was similar (P > .05) between the two groups. CONCLUSION Dual-energy CTPA with image reconstruction at 50 keV allows a significant reduction in iodine load while improving intravascular signal intensity, maintaining SNR and with comparable radiation dose.
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Affiliation(s)
- Ren Yuan
- Department of Radiology, St Paul's Hospital, University of British Columbia, 1081 Burrard St, Vancouver, BC, Canada
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Effect of positive end-expiratory pressure on regional ventilation distribution during bronchoconstriction in rabbit studied by synchrotron radiation imaging. Crit Care Med 2011; 39:1731-8. [PMID: 21494104 DOI: 10.1097/ccm.0b013e318218a375] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess the effects of positive end-expiratory pressure on regional ventilation distribution in normal lung and after histamine-induced bronchoconstriction. DESIGN Experimental study. SETTING International research laboratory. SUBJECTS Six healthy New Zealand rabbits weighing 2.5 ± 0.1 kg. INTERVENTIONS Rabbits were anesthetized, tracheostomized, paralyzed, and mechanically ventilated. Synchrotron radiation computed tomography images of tissue density and specific ventilation were acquired using K-edge subtraction imaging with inhaled stable xenon gas in middle and caudal thoracic levels on 0 and 5 cm H(2)O positive end-expiratory pressure at baseline and twice after histamine inhalation. MEASUREMENTS AND MAIN RESULTS At baseline, a positive end-expiratory pressure of 5 cm H(2)O significantly increased lung volume. Histamine inhalation caused patchy areas of decreased specific ventilation, including some areas with no ventilation. After histamine, positive end-expiratory pressure significantly increased the area of well-ventilated lung regions and decreased the heterogeneity of specific ventilation. This improvement went together with a significant but limited increase in the area of hyperinflated lung zones. CONCLUSIONS The findings of this study suggest that in mechanically ventilated rabbit with severely heterogeneous bronchoconstriction, a positive end-expiratory pressure of 5 cm H(2)O significantly improves regional ventilation homogeneity through dilation of flow-limited airways and recruitment of closed airways.
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Shi C, Boehme S, Hartmann EK, Markstaller K. Novel technologies to detect atelectotrauma in the injured lung. Exp Lung Res 2010; 37:18-25. [PMID: 20860539 DOI: 10.3109/01902148.2010.501402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO₂ within a respiratory cycle. Continuous, ultrafast, on-line in vivo measurement of PaO₂ can be provided by an indwelling PaO₂ probe. In addition, monitoring of fast changes in SaO₂ by pulse oximetry technology at the bedside could also be used to detect those fast changes in oxygenation.
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Affiliation(s)
- Chang Shi
- Department of Anesthesiology, Medical Center of the Johannes-Gutenberg-University, Mainz, Germany.
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Kang MJ, Park CM, Lee CH, Goo JM, Lee HJ. Dual-energy CT: clinical applications in various pulmonary diseases. Radiographics 2010; 30:685-98. [PMID: 20462988 DOI: 10.1148/rg.303095101] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The dual-energy computed tomographic (CT) technique allows the differentiation of materials with large atomic numbers such as iodine and xenon. The basic principle of dual-energy CT is material decomposition based on attenuation differences at different energy levels. By using dual-energy CT angiography for the evaluation of perfusion defects in cases of pulmonary embolism, and using xenon CT for the evaluation of ventilation defects, it may be possible to replace perfusion and ventilation scanning. An iodine map from dual-energy CT can demonstrate the distribution of pulmonary perfusion, whereas xenon ventilation CT can be used to generate a ventilation map. Furthermore, the virtual nonenhanced dual-energy CT technique can be used for the evaluation of pulmonary nodule characteristics without acquisition of true nonenhanced CT images. Knowledge of the applications of dual-energy CT and the typical images produced may lead to wider use of dual-energy CT for pulmonary applications and better interpretation of the results.
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Affiliation(s)
- Mi-Jin Kang
- Department of Radiology, Seoul National University Hospital, 28 Yeongeon-dong, Jongno-gu, Seoul 110-744, Korea
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Beltran MA, Paganin DM, Uesugi K, Kitchen MJ. 2D and 3D X-ray phase retrieval of multi-material objects using a single defocus distance. OPTICS EXPRESS 2010; 18:6423-36. [PMID: 20389666 DOI: 10.1364/oe.18.006423] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A method of tomographic phase retrieval is developed for multi-material objects whose components each has a distinct complex refractive index. The phase-retrieval algorithm, based on the Transport-of-Intensity equation, utilizes propagation-based X-ray phase contrast images acquired at a single defocus distance for each tomographic projection. The method requires a priori knowledge of the complex refractive index for each material present in the sample, together with the total projected thickness of the object at each orientation. The requirement of only a single defocus distance per projection simplifies the experimental setup and imposes no additional dose compared to conventional tomography. The algorithm was implemented using phase contrast data acquired at the SPring-8 Synchrotron facility in Japan. The three-dimensional (3D) complex refractive index distribution of a multi-material test object was quantitatively reconstructed using a single X-ray phase-contrast image per projection. The technique is robust in the presence of noise, compared to conventional absorption based tomography.
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Affiliation(s)
- M A Beltran
- School of Physics, Monash University, VIC 3800, Australia.
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40
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Bayat S, Strengell S, Porra L, Janosi TZ, Petak F, Suhonen H, Suortti P, Hantos Z, Sovijärvi ARA, Habre W. Methacholine and ovalbumin challenges assessed by forced oscillations and synchrotron lung imaging. Am J Respir Crit Care Med 2009; 180:296-303. [PMID: 19483115 DOI: 10.1164/rccm.200808-1211oc] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Methacholine (Mch) is routinely used to assess bronchial hyperreactivity; however, little is known about the differences in the lung response pattern between this provocation and that observed with ovalbumin (Ova) after allergic sensitization. OBJECTIVES To compare (1) the central versus peripheral effects of Mch and Ova within the lung by combining measurements of airway and tissue mechanics with synchrotron radiation (SR) imaging, and (2) to assess the extent to which mechanical and imaging parameters are correlated. METHODS We used the low-frequency forced oscillation technique and SR imaging in control (n = 12) and ovalbumin-sensitized (n = 13) rabbits, at baseline, during intravenous Mch infusion (2.5 microg/kg/min, 5.0 microg/kg/min, or 10.0 microg/kg/min), after recovery from Mch, and after intravenous Ova injection (2.0 mg). We compared intravenous Mch challenge with inhaled Mch (125 mg/ml, 90 s) in a separate group of control animals (n = 5). MEASUREMENTS AND MAIN RESULTS Airway conductance and tissue elastance were measured by low-frequency forced oscillation technique. The central airway cross-sectional area, the ventilated alveolar area, and the heterogeneity of specific ventilation were quantified by SR imaging. Mch infusion induced constriction predominantly in the central airways, whereas Ova provocation affected mainly the peripheral airways, leading to severe ventilation heterogeneities in sensitized animals. Mch inhalation affected both conducting and peripheral airways. The correlations between airway conductance and central airway cross-sectional area (R = 0.71) and between tissue elastance and ventilated alveolar area (R = -0.72) were strong. CONCLUSIONS The pattern of lung response caused by intravenous Mch and Ova are fundamentally different. Although inhaled Mch induces a heterogeneous lung response similar to that observed with intravenous allergen, these similar patterns are due to different mechanisms.
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Affiliation(s)
- Sam Bayat
- Université de Picardie Jules Verne, EA4285 Péritox-INERIS and CHU Amiens, Amiens, France.
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Abstract
Significant advances continue in the subjective and quantifiable imaging features of asthma. Radiologists need to be aware of not only the general features, but also potential asthma mimics as well as complications.
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Affiliation(s)
- Alyn Q Woods
- Division of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA.
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Bayat S, Porra L, Suhonen H, Suortti P, Sovijärvi ARA. Paradoxical conducting airway responses and heterogeneous regional ventilation after histamine inhalation in rabbit studied by synchrotron radiation CT. J Appl Physiol (1985) 2009; 106:1949-58. [PMID: 19359611 DOI: 10.1152/japplphysiol.90550.2008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We studied both central conducting airway response and changes in the distribution of regional ventilation induced by inhaled histamine in healthy anesthetized and mechanically ventilated rabbit using a novel xenon-enhanced synchrotron radiation computed tomography (CT) imaging technique, K-edge subtraction imaging (KES). Images of specific ventilation were obtained using serial KES during xenon washin, in three axial lung slices, at baseline and twice after inhalation of histamine aerosol (50 or 125 mg/ml) in two groups of animals (n = 6 each). Histamine inhalation caused large clustered areas of poor ventilation, characterized by a drop in average specific ventilation (sV(m)), but an increase in sV(m) in the remaining lung zones indicating ventilation redistribution. Ventilation heterogeneity, estimated as coefficient of variation (CV) of sV(m) significantly increased following histamine inhalation. The area of ventilation defects and CV were significantly larger with the higher histamine dose. In conducting airways, histamine inhalation caused a heterogeneous airway response combining narrowing and dilatation in individual airways of different generations, with the probability for constriction increasing peripherally. This finding provides further in vivo evidence that airway reactivity in response to inhaled histamine is complex and that airway response may vary substantially with location within the bronchial tree.
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Affiliation(s)
- Sam Bayat
- Centre Hospitalier Universitaire d'Amiens, Cardiologie et Pneumo-Allergologie Pédiatriques, 80054 Amiens Cedex 1, France.
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Schültke E, Fiedler S, Nemoz C, Ogieglo L, Kelly ME, Crawford P, Esteve F, Brochard T, Renier M, Requardt H, Le Duc G, Juurlink B, Meguro K. Synchrotron-based intra-venous K-edge digital subtraction angiography in a pig model: a feasibility study. Eur J Radiol 2009; 73:677-81. [PMID: 19233584 DOI: 10.1016/j.ejrad.2009.01.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 01/08/2009] [Accepted: 01/15/2009] [Indexed: 10/21/2022]
Abstract
BACKGROUND K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients. MATERIALS AND METHODS This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. RESULTS After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5mm diameter.
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Affiliation(s)
- Elisabeth Schültke
- Department of Surgery, University of Saskatchewan, Saskatoon, SK, Canada.
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Adam JF, Bayat S, Porra L, Elleaume H, Estève F, Suortti P. QUANTITATIVE FUNCTIONAL IMAGING AND KINETIC STUDIES WITH HIGH-Z CONTRAST AGENTS USING SYNCHROTRON RADIATION COMPUTED TOMOGRAPHY. Clin Exp Pharmacol Physiol 2009; 36:95-106. [DOI: 10.1111/j.1440-1681.2008.05043.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kitchen MJ, Lewis RA, Morgan MJ, Wallace MJ, Siew ML, Siu KKW, Habib A, Fouras A, Yagi N, Uesugi K, Hooper SB. Dynamic measures of regional lung air volume using phase contrast x-ray imaging. Phys Med Biol 2008; 53:6065-77. [DOI: 10.1088/0031-9155/53/21/012] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Bayat S, Porra L, Suhonen H, Janosi T, Strengell S, Habre W, Petak F, Hantos Z, Suortti P, Sovijärvi A. Imaging of lung function using synchrotron radiation computed tomography: what's new? Eur J Radiol 2008; 68:S78-83. [PMID: 18606518 DOI: 10.1016/j.ejrad.2008.04.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 04/25/2008] [Indexed: 10/21/2022]
Abstract
There is a growing interest in imaging techniques as non-invasive means of quantitatively measuring regional lung structure and function. Abnormalities in lung ventilation due to alterations in airway function such as those observed in asthma and COPD are highly heterogeneous, and experimental methods to study this heterogeneity are crucial for better understanding of disease mechanisms and drug targeting strategies. In severe obstructive diseases requiring mechanical ventilation, the optimal ventilatory strategy to achieve recruitment of poorly ventilated lung zones remains a matter of considerable debate. We have used synchrotron radiation computed tomography (SRCT) for the in vivo study of regional lung ventilation and airway function. This imaging technique allows direct quantification of stable Xenon (Xe) gas used as an inhaled contrast agent using K-edge subtraction imaging. Dynamics of Xe wash-in can be used to calculate quantitative maps of regional specific lung ventilation. More recently, the development of Spiral-CT has allowed the acquisition of 3D images of the pulmonary bronchial tree and airspaces. This technique gives access to quantitative measurements of regional lung volume, ventilation, and mechanical properties. Examples of application in an experimental model of allergic asthma and in imaging lung recruitment as a function of mechanical ventilation parameters will be presented. The future orientations of this technique will be discussed.
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Affiliation(s)
- Sam Bayat
- Université de Picardie Jules Verne, Département de Physiologie, DMAG EA 3901, 3 Rue des Louvels, 80036 Amiens Cedex 1, France.
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Affiliation(s)
- Michael Puderbach
- Department of Radiology, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Abstract
Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled multi-detector row CT allow for quantification of presence and distribution of parenchymal and airway pathology; xenon gas can be employed to assess regional ventilation of the lungs, and rapid bolus injections of iodinated contrast agent can provide a quantitative measure of regional parenchymal perfusion. Advances in MRI of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized gas imaging, which allow functional assessment, including ventilation/perfusion, microscopic air space measurements, and gas flow and transport dynamics.
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Affiliation(s)
- Edwin J R van Beek
- Department of Radiology, Carver College of Medicine, University of Iowa, C-751 GH, 200 Hawkins Drive, Iowa City, IA 52242-1077, USA.
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Suhonen H, Porra L, Bayat S, Sovijärvi ARA, Suortti P. Simultaneousin vivosynchrotron radiation computed tomography of regional ventilation and blood volume in rabbit lung using combined K-edge and temporal subtraction. Phys Med Biol 2008; 53:775-91. [DOI: 10.1088/0031-9155/53/3/016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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