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Uzundurukan A, Poncet S, Boffito DC, Micheau P. CT-FEM of the human thorax: Frequency response function and 3D harmonic analysis at resonance. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 246:108062. [PMID: 38359553 DOI: 10.1016/j.cmpb.2024.108062] [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: 11/30/2023] [Revised: 01/30/2024] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND AND OBJECTIVE High-frequency chest wall compression (HFCC) therapy by airway clearance devices (ACDs) acts on the rheological properties of bronchial mucus to assist in clearing pulmonary secretions. Investigating low-frequency vibrations on the human thorax through numerical simulations is critical to ensure consistency and repeatability of studies by reducing extreme variability in body measurements across individuals. This study aims to present the numerical investigation of the harmonic acoustic excitation of ACDs on the human chest as a gentle and effective HFCC therapy. METHODS Four software programs were sequentially used to visualize medical images, decrease the number of surfaces, generate and repair meshes, and conduct numerical analysis, respectively. The developed methodology supplied the validation of the effect of HFCC through computed tomography-based finite element analysis (CT-FEM) of a human thorax. To illustrate the vibroacoustic characteristics of the HFCC therapy device, a 146-decibel sound pressure level (dBSPL) was applied on the back-chest surface of the model. Frequency response function (FRF) across 5-100 Hz was analyzed to characterize the behaviour of the human thorax with the state-space model. RESULTS We discovered that FRF pertaining to accelerance equals 0.138 m/s2N at the peak frequency of 28 Hz, which is consistent with two independent experimental airway clearance studies reported in the literature. The state-space model assessed two apparent resonance frequencies at 28 Hz and 41 Hz for the human thorax. The total displacement, kinetic energy density, and elastic strain energy density were furthermore quantified at 1 µm, 5.2 µJ/m3, and 140.7 µJ/m3, respectively, at the resonance frequency. In order to deepen our understanding of the impact on internal organs, the model underwent simulations in both the time domain and frequency domain for a comprehensive analysis. CONCLUSION Overall, the present study enabled determining and validating FRF of the human thorax to roll out the inconsistencies, contributing to the health of individuals with investigating gentle but effective HFCC therapy conditions with ACDs. This innovative finding furthermore provides greater clarity and a tangible understanding of the subject by simulating the responses of CT-FEM of the human thorax and internal organs at resonance.
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Affiliation(s)
- Arife Uzundurukan
- Centre de Recherche Acoustique-Signal-Humain, Université de Sherbrooke, 2500 Bd de l'Université, Sherbrooke, QC J1K 2R1, Canada.
| | - Sébastien Poncet
- Centre de Recherche Acoustique-Signal-Humain, Université de Sherbrooke, 2500 Bd de l'Université, Sherbrooke, QC J1K 2R1, Canada
| | - Daria Camilla Boffito
- Department of Chemical Engineering, École Polytechnique de Montréal, 2500 Chem. de Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Philippe Micheau
- Centre de Recherche Acoustique-Signal-Humain, Université de Sherbrooke, 2500 Bd de l'Université, Sherbrooke, QC J1K 2R1, Canada
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Hsia CCW, Bates JHT, Driehuys B, Fain SB, Goldin JG, Hoffman EA, Hogg JC, Levin DL, Lynch DA, Ochs M, Parraga G, Prisk GK, Smith BM, Tawhai M, Vidal Melo MF, Woods JC, Hopkins SR. Quantitative Imaging Metrics for the Assessment of Pulmonary Pathophysiology: An Official American Thoracic Society and Fleischner Society Joint Workshop Report. Ann Am Thorac Soc 2023; 20:161-195. [PMID: 36723475 PMCID: PMC9989862 DOI: 10.1513/annalsats.202211-915st] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Multiple thoracic imaging modalities have been developed to link structure to function in the diagnosis and monitoring of lung disease. Volumetric computed tomography (CT) renders three-dimensional maps of lung structures and may be combined with positron emission tomography (PET) to obtain dynamic physiological data. Magnetic resonance imaging (MRI) using ultrashort-echo time (UTE) sequences has improved signal detection from lung parenchyma; contrast agents are used to deduce airway function, ventilation-perfusion-diffusion, and mechanics. Proton MRI can measure regional ventilation-perfusion ratio. Quantitative imaging (QI)-derived endpoints have been developed to identify structure-function phenotypes, including air-blood-tissue volume partition, bronchovascular remodeling, emphysema, fibrosis, and textural patterns indicating architectural alteration. Coregistered landmarks on paired images obtained at different lung volumes are used to infer airway caliber, air trapping, gas and blood transport, compliance, and deformation. This document summarizes fundamental "good practice" stereological principles in QI study design and analysis; evaluates technical capabilities and limitations of common imaging modalities; and assesses major QI endpoints regarding underlying assumptions and limitations, ability to detect and stratify heterogeneous, overlapping pathophysiology, and monitor disease progression and therapeutic response, correlated with and complementary to, functional indices. The goal is to promote unbiased quantification and interpretation of in vivo imaging data, compare metrics obtained using different QI modalities to ensure accurate and reproducible metric derivation, and avoid misrepresentation of inferred physiological processes. The role of imaging-based computational modeling in advancing these goals is emphasized. Fundamental principles outlined herein are critical for all forms of QI irrespective of acquisition modality or disease entity.
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Deep 3D reconstruction of synchrotron X-ray computed tomography for intact lungs. Sci Rep 2023; 13:1738. [PMID: 36720962 PMCID: PMC9889716 DOI: 10.1038/s41598-023-27627-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/04/2023] [Indexed: 02/02/2023] Open
Abstract
Synchrotron X-rays can be used to obtain highly detailed images of parts of the lung. However, micro-motion artifacts induced by such as cardiac motion impede quantitative visualization of the alveoli in the lungs. This paper proposes a method that applies a neural network for synchrotron X-ray Computed Tomography (CT) data to reconstruct the high-quality 3D structure of alveoli in intact mouse lungs at expiration, without needing ground-truth data. Our approach reconstructs the spatial sequence of CT images by using a deep-image prior with interpolated input latent variables, and in this way significantly enhances the images of alveolar structure compared with the prior art. The approach successfully visualizes 3D alveolar units of intact mouse lungs at expiration and enables us to measure the diameter of the alveoli. We believe that our approach helps to accurately visualize other living organs hampered by micro-motion.
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Preclinical MRI Using Hyperpolarized 129Xe. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238338. [PMID: 36500430 PMCID: PMC9738892 DOI: 10.3390/molecules27238338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 12/05/2022]
Abstract
Although critical for development of novel therapies, understanding altered lung function in disease models is challenging because the transport and diffusion of gases over short distances, on which proper function relies, is not readily visualized. In this review we summarize progress introducing hyperpolarized 129Xe imaging as a method to follow these processes in vivo. The work is organized in sections highlighting methods to observe the gas replacement effects of breathing (Gas Dynamics during the Breathing Cycle) and gas diffusion throughout the parenchymal airspaces (3). We then describe the spectral signatures indicative of gas dissolution and uptake (4), and how these features can be used to follow the gas as it enters the tissue and capillary bed, is taken up by hemoglobin in the red blood cells (5), re-enters the gas phase prior to exhalation (6), or is carried via the vasculature to other organs and body structures (7). We conclude with a discussion of practical imaging and spectroscopy techniques that deliver quantifiable metrics despite the small size, rapid motion and decay of signal and coherence characteristic of the magnetically inhomogeneous lung in preclinical models (8).
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Sznitman J. Revisiting Airflow and Aerosol Transport Phenomena in the Deep Lungs with Microfluidics. Chem Rev 2021; 122:7182-7204. [PMID: 34964615 DOI: 10.1021/acs.chemrev.1c00621] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The dynamics of respiratory airflows and the associated transport mechanisms of inhaled aerosols characteristic of the deep regions of the lungs are of broad interest in assessing both respiratory health risks and inhalation therapy outcomes. In the present review, we present a comprehensive discussion of our current understanding of airflow and aerosol transport phenomena that take place within the unique and complex anatomical environment of the deep lungs, characterized by submillimeter 3D alveolated airspaces and nominally slow resident airflows, known as low-Reynolds-number flows. We exemplify the advances brought forward by experimental efforts, in conjunction with numerical simulations, to revisit past mechanistic theories of respiratory airflow and particle transport in the distal acinar regions. Most significantly, we highlight how microfluidic-based platforms spanning the past decade have accelerated opportunities to deliver anatomically inspired in vitro solutions that capture with sufficient realism and accuracy the leading mechanisms governing both respiratory airflow and aerosol transport at true scale. Despite ongoing challenges and limitations with microfabrication techniques, the efforts witnessed in recent years have provided previously unattainable in vitro quantifications on the local transport properties in the deep pulmonary acinar airways. These may ultimately provide new opportunities to explore improved strategies of inhaled drug delivery to the deep acinar regions by investigating further the mechanistic interactions between airborne particulate carriers and respiratory airflows at the pulmonary microscales.
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Affiliation(s)
- Josué Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel
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Lv H, Dong J, Yang Y, Zhu Y. Reply to the 'Comment on "Microflow in a rhythmically expanding alveolar chip with dynamic similarity"' by A. Tsuda and F. S. Henry, Lab Chip, 2021, 21, DOI. LAB ON A CHIP 2021; 21:1431-1432. [PMID: 33881031 DOI: 10.1039/d0lc01271h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This article provides our response to a comment on our article published in Lab on a Chip (H. Lv, J. Dong, Y. Qiu, Y. Yang and Y. Zhu, Lab Chip, 2020, 20, 2394-2402) by Tsuda and Henry, Lab Chip, 2020.
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Affiliation(s)
- Huimin Lv
- School of Science, Harbin Institute of Technology, Shenzhen, 518055 China
| | - Jun Dong
- School of Science, Harbin Institute of Technology, Shenzhen, 518055 China
| | - Yue Yang
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, 518055, China.
| | - Yonggang Zhu
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, 518055, China.
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Airspace Dimension Assessment (AiDA) by inhaled nanoparticles: benchmarking with hyperpolarised 129Xe diffusion-weighted lung MRI. Sci Rep 2021; 11:4721. [PMID: 33633165 PMCID: PMC7907057 DOI: 10.1038/s41598-021-83975-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/10/2021] [Indexed: 11/26/2022] Open
Abstract
Enlargements of distal airspaces can indicate pathological changes in the lung, but accessible and precise techniques able to measure these regions are lacking. Airspace Dimension Assessment with inhaled nanoparticles (AiDA) is a new method developed for in vivo measurement of distal airspace dimensions. The aim of this study was to benchmark the AiDA method against quantitative measurements of distal airspaces from hyperpolarised 129Xe diffusion-weighted (DW)-lung magnetic resonance imaging (MRI). AiDA and 129Xe DW-MRI measurements were performed in 23 healthy volunteers who spanned an age range of 23–70 years. The relationship between the 129Xe DW-MRI and AiDA metrics was tested using Spearman’s rank correlation coefficient. Significant correlations were observed between AiDA distal airspace radius (rAiDA) and mean 129Xe apparent diffusion coefficient (ADC) (p < 0.005), distributed diffusivity coefficient (DDC) (p < 0.001) and distal airspace dimension (LmD) (p < 0.001). A mean bias of − 1.2 µm towards rAiDA was observed between 129Xe LmD and rAiDA, indicating that rAiDA is a measure of distal airspace dimension. The AiDA R0 intercept correlated with MRI 129Xe α (p = 0.02), a marker of distal airspace heterogeneity. This study demonstrates that AiDA has potential to characterize the distal airspace microstructures and may serve as an alternative method for clinical examination of the lungs.
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Chan HF, Collier GJ, Parra-Robles J, Wild JM. Finite element simulations of hyperpolarized gas DWI in micro-CT meshes of acinar airways: validating the cylinder and stretched exponential models of lung microstructural length scales. Magn Reson Med 2021; 86:514-525. [PMID: 33624325 DOI: 10.1002/mrm.28703] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 12/07/2020] [Accepted: 01/07/2021] [Indexed: 12/24/2022]
Abstract
PURPOSE This work assesses the accuracy of the stretched exponential (SEM) and cylinder models of lung microstructural length scales that can be derived from hyperpolarized gas DWI. This was achieved by simulating 3 He and 129 Xe DWI signals within two micro-CT-derived realistic acinar airspace meshes that represent healthy and idiopathic pulmonary fibrosis lungs. METHODS The healthy and idiopathic pulmonary fibrosis acinar airway meshes were derived from segmentations of 3D micro-CT images of excised human lungs and meshed for finite element simulations of the Bloch-Torrey equations. 3 He and 129 Xe multiple b value DWI experiments across a range of diffusion times (3 He Δ = 1.6 ms; 129 Xe Δ = 5 to 20 ms) were simulated in each mesh. Global SEM mean diffusive length scale and cylinder model mean chord length value was derived from each finite element simulation and compared against each mesh's mean linear intercept length, calculated from intercept length measurements within micro-CT segmentation masks. RESULTS The SEM-derived mean diffusive length scale was within ±10% of the mean linear intercept length for simulations with both 3 He (Δ = 1.6 ms) and 129 Xe (Δ = 7 to 13 ms) in the healthy mesh, and with 129 Xe (Δ = 13 to 20 ms) for the idiopathic pulmonary fibrosis mesh, whereas for the cylinder model-derived mean chord length the closest agreement with mean linear intercept length (11.7% and 22.6% difference) was at 129 Xe Δ = 20 ms for both healthy and IPF meshes, respectively. CONCLUSION This work validates the use of the SEM for accurate estimation of acinar dimensions and indicates that the SEM is relatively robust across a range of experimental conditions and acinar length scales.
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Affiliation(s)
- Ho-Fung Chan
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Guilhem J Collier
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Juan Parra-Robles
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.,Faculty of Pharmacy, Universidad Complutense de Madrid, Madrid, Spain
| | - Jim M Wild
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.,Insigneo, Institute for in Silico Medicine, University of Sheffield, Sheffield, United Kingdom
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Maunder A, Chan HF, Hughes PJC, Collier G, Norquay G, Rodgers O, Thelwall P, Robb F, Rao M, Wild JM. MR properties of 19 F C 3 F 8 gas in the lungs of healthy volunteers: T 2 ∗ and apparent diffusion coefficient at 1.5T and T 2 ∗ at 3T. Magn Reson Med 2020; 85:1561-1570. [PMID: 32926448 DOI: 10.1002/mrm.28511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 08/08/2020] [Accepted: 08/17/2020] [Indexed: 01/07/2023]
Abstract
PURPOSE To measure the transverse relaxation time ( T 2 ∗ ) and apparent diffusion coefficient (ADC) of 19 F-C3 F8 gas in vivo in human lungs at 1.5T and 3T, and to determine the representative distribution of values of these parameters in a cohort of healthy volunteers. METHODS Mapping of ADC at lung inflation levels of functional residual capacity (FRC) and total lung capacity (TLC) was performed with inhaled 19 F-C3 F8 (eight subjects) and 129 Xe (six subjects) at 1.5T. T 2 ∗ mapping with 19 F-C3 F8 was performed at 1.5T (at FRC and TLC) for 8 subjects and at 3T (at TLC for seven subjects). RESULTS At both FRC and TLC, the 19 F-C3 F8 ADC was smaller than the free diffusion coefficient demonstrating airway microstructural diffusion restriction. From FRC to TLC, the mean ADC significantly increased from 1.56 mm2 /s to 1.83 mm2 /s (P = .0017) for 19 F-C3 F8, and from 2.49 mm2 /s to 3.38 mm2 /s (P = .0015) for 129 Xe. The posterior-to-anterior gradient in ADC for FRC versus TLC in the superior half of the lungs was measured as 0.0308 mm2 /s per cm versus 0.0168 mm2 /s per cm for 19 F-C3 F8 and 0.0871 mm2 /s per cm versus 0.0326 mm2 /s per cm for 129 Xe. A consistent distribution of 19 F-C3 F8 T 2 ∗ values was observed in the lungs, with low values observed near the diaphragm and large pulmonary vessels. The mean T 2 ∗ across volunteers was 4.48 ms at FRC and 5.33 ms at TLC for 1.5T, and 3.78 ms at TLC for 3T. CONCLUSION In this feasibility study, values of physiologically relevant parameters of lung microstructure measurable by MRI ( T 2 ∗ , and ADC) were established for C3 F8 in vivo lung imaging in healthy volunteers.
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Affiliation(s)
- Adam Maunder
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Ho-Fung Chan
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Paul J C Hughes
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Guillhem Collier
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Graham Norquay
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Oliver Rodgers
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Peter Thelwall
- Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Fraser Robb
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom.,GE Healthcare, Aurora, Ohio, USA
| | - Madhwesha Rao
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Jim M Wild
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
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Matuszak J, Tabuchi A, Kuebler WM. Ventilation and Perfusion at the Alveolar Level: Insights From Lung Intravital Microscopy. Front Physiol 2020; 11:291. [PMID: 32308629 PMCID: PMC7145899 DOI: 10.3389/fphys.2020.00291] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 03/16/2020] [Indexed: 01/13/2023] Open
Abstract
Intravital microscopy (IVM) offers unique possibilities for the observation of biological processes and disease related mechanisms in vivo. Especially for anatomically complex and dynamic organs such as the lung and its main functional unit, the alveolus, IVM provides exclusive advantages in terms of spatial and temporal resolution. By the use of lung windows, which have advanced and improved over time, direct access to the lung surface is provided. In this review we will discuss two main topics, namely alveolar dynamics and perfusion from the perspective of IVM-based studies. Of special interest are unanswered questions regarding alveolar dynamics such as: What are physiologic alveolar dynamics? How do these dynamics change under pathologic conditions and how do those changes contribute to ventilator-induced lung injury? How can alveolar dynamics be targeted in a beneficial way? With respect to alveolar perfusion IVM has propelled our understanding of the pulmonary microcirculation and its perfusion, as well as pulmonary vasoreactivity, permeability and immunological aspects. Whereas the general mechanism behind these processes are understood, we still lack a proper understanding of the complex, multidimensional interplay between alveolar ventilation and microvascular perfusion, capillary recruitment, or vascular immune responses under physiologic and pathologic conditions. These are only part of the unanswered questions and problems, which we still have to overcome. IVM as the tool of choice might allow us to answer part of these questions within the next years or decades. As every method, IVM has advantages as well as limitations, which have to be taken into account for data analysis and interpretation, which will be addressed in this review.
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Affiliation(s)
- Jasmin Matuszak
- Institute of Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Arata Tabuchi
- The Keenan Research Centre for Biomedical Science at St. Michael's, Toronto, ON, Canada
| | - Wolfgang M Kuebler
- Institute of Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Departments of Surgery and Physiology, University of Toronto, Toronto, ON, Canada
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Scaramuzzo G, Broche L, Pellegrini M, Porra L, Derosa S, Tannoia AP, Marzullo A, Borges JB, Bayat S, Bravin A, Larsson A, Perchiazzi G. The Effect of Positive End-Expiratory Pressure on Lung Micromechanics Assessed by Synchrotron Radiation Computed Tomography in an Animal Model of ARDS. J Clin Med 2019; 8:jcm8081117. [PMID: 31357677 PMCID: PMC6723999 DOI: 10.3390/jcm8081117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/17/2019] [Accepted: 07/25/2019] [Indexed: 02/06/2023] Open
Abstract
Modern ventilatory strategies are based on the assumption that lung terminal airspaces act as isotropic balloons that progressively accommodate gas. Phase contrast synchrotron radiation computed tomography (PCSRCT) has recently challenged this concept, showing that in healthy lungs, deflation mechanisms are based on the sequential de-recruitment of airspaces. Using PCSRCT scans in an animal model of acute respiratory distress syndrome (ARDS), this study examined whether the numerosity (ASnum) and dimension (ASdim) of lung airspaces change during a deflation maneuver at decreasing levels of positive end-expiratory pressure (PEEP) at 12, 9, 6, 3, and 0 cmH2O. Deflation was associated with significant reduction of ASdim both in the whole lung section (passing from from 13.1 ± 2.0 at PEEP 12 to 7.6 ± 4.2 voxels at PEEP 0) and in single concentric regions of interest (ROIs). However, the regression between applied PEEP and ASnum was significant in the whole slice (ranging from 188 ± 52 at PEEP 12 to 146.4 ± 96.7 at PEEP 0) but not in the single ROIs. This mechanism of deflation in which reduction of ASdim is predominant, differs from the one observed in healthy conditions, suggesting that the peculiar alveolar micromechanics of ARDS might play a role in the deflation process.
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Affiliation(s)
- Gaetano Scaramuzzo
- Department of Morphology, Surgery and Experimental Medicine, Ferrara University, 44121 Ferrara, Italy
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Ludovic Broche
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Mariangela Pellegrini
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, 75185 Uppsala, Sweden
| | - Liisa Porra
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
- Helsinki University Hospital, FI-00029 Helsinki, Finland
| | - Savino Derosa
- Department of Emergency and Organ Transplant, Bari University, 70124 Bari, Italy
| | | | - Andrea Marzullo
- Department of Emergency and Organ Transplant, Bari University, 70124 Bari, Italy
| | - João Batista Borges
- Centre for Human and Applied Physiological Sciences, Faculty of Sciences and Medicine, King's College, London WC2R 2LS, UK
| | - Sam Bayat
- The European Synchrotron Radiation Facility, 38043 Grenoble, France
- INSERM UA7, Synchrotron Radiation for Biomedicine (STROBE) Laboratory, University of Grenoble Alpes, 38043 Grenoble, France
| | - Alberto Bravin
- The European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Gaetano Perchiazzi
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden.
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, 75185 Uppsala, Sweden.
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Grune J, Tabuchi A, Kuebler WM. Alveolar dynamics during mechanical ventilation in the healthy and injured lung. Intensive Care Med Exp 2019; 7:34. [PMID: 31346797 PMCID: PMC6658629 DOI: 10.1186/s40635-019-0226-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 02/13/2019] [Indexed: 02/12/2023] Open
Abstract
Mechanical ventilation is a life-saving therapy in patients with acute respiratory distress syndrome (ARDS). However, mechanical ventilation itself causes severe co-morbidities in that it can trigger ventilator-associated lung injury (VALI) in humans or ventilator-induced lung injury (VILI) in experimental animal models. Therefore, optimization of ventilation strategies is paramount for the effective therapy of critical care patients. A major problem in the stratification of critical care patients for personalized ventilation settings, but even more so for our overall understanding of VILI, lies in our limited insight into the effects of mechanical ventilation at the actual site of injury, i.e., the alveolar unit. Unfortunately, global lung mechanics provide for a poor surrogate of alveolar dynamics and methods for the in-depth analysis of alveolar dynamics on the level of individual alveoli are sparse and afflicted by important limitations. With alveolar dynamics in the intact lung remaining largely a "black box," our insight into the mechanisms of VALI and VILI and the effectiveness of optimized ventilation strategies is confined to indirect parameters and endpoints of lung injury and mortality.In the present review, we discuss emerging concepts of alveolar dynamics including alveolar expansion/contraction, stability/instability, and opening/collapse. Many of these concepts remain still controversial, in part due to limitations of the different methodologies applied. We therefore preface our review with an overview of existing technologies and approaches for the analysis of alveolar dynamics, highlighting their individual strengths and limitations which may provide for a better appreciation of the sometimes diverging findings and interpretations. Joint efforts combining key technologies in identical models to overcome the limitations inherent to individual methodologies are needed not only to provide conclusive insights into lung physiology and alveolar dynamics, but ultimately to guide critical care patient therapy.
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Affiliation(s)
- Jana Grune
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, 10117 Berlin, Germany
| | - Arata Tabuchi
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Wolfgang M. Kuebler
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, 10117 Berlin, Germany
- The Keenan Research Centre for Biomedical Science at St. Michael’s, Toronto, Canada
- Departments of Surgery and Physiology, University of Toronto, Toronto, Canada
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Scaramuzzo G, Broche L, Pellegrini M, Porra L, Derosa S, Tannoia AP, Marzullo A, Borges JB, Bayat S, Bravin A, Larsson A, Perchiazzi G. Regional Behavior of Airspaces During Positive Pressure Reduction Assessed by Synchrotron Radiation Computed Tomography. Front Physiol 2019; 10:719. [PMID: 31231245 PMCID: PMC6567926 DOI: 10.3389/fphys.2019.00719] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 05/23/2019] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION The mechanisms of lung inflation and deflation are only partially known. Ventilatory strategies to support lung function rely upon the idea that lung alveoli are isotropic balloons that progressively inflate or deflate and that lung pressure/volume curves derive only by the interplay of critical opening pressures, critical closing pressures, lung history, and position of alveoli inside the lung. This notion has been recently challenged by subpleural microscopy, magnetic resonance, and computed tomography (CT). Phase-contrast synchrotron radiation CT (PC-SRCT) can yield in vivo images at resolutions higher than conventional CT. OBJECTIVES We aimed to assess the numerosity (ASden) and the extension of the surface of airspaces (ASext) in healthy conditions at different volumes, during stepwise lung deflation, in concentric regions of the lung. METHODS The study was conducted in seven anesthetized New Zealand rabbits. They underwent PC-SRCT scans (resolution of 47.7 μm) of the lung at five decreasing positive end expiratory pressure (PEEP) levels of 12, 9, 6, 3, and 0 cmH2O during end-expiratory holds. Three concentric regions of interest (ROIs) of the lung were studied: subpleural, mantellar, and core. The images were enhanced by phase contrast algorithms. ASden and ASext were computed by using the Image Processing Toolbox for MatLab. Statistical tests were used to assess any significant difference determined by PEEP or ROI on ASden and ASext. RESULTS When reducing PEEP, in each ROI the ASden significantly decreased. Conversely, ASext variation was not significant except for the core ROI. In the latter, the angular coefficient of the regression line was significantly low. CONCLUSION The main mechanism behind the decrease in lung volume at PEEP reduction is derecruitment. In our study involving lung regions laying on isogravitational planes and thus equally influenced by gravitational forces, airspace numerosity and extension of surface depend on the local mechanical properties of the lung.
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Affiliation(s)
- Gaetano Scaramuzzo
- Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Ludovic Broche
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
- The European Synchrotron Radiation Facility, Grenoble, France
- INSERM UA7, Synchrotron Radiation for Biomedicine (STROBE) Laboratory, Grenoble Alpes University, Amiens, France
| | - Mariangela Pellegrini
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
| | - Liisa Porra
- Department of Physics, Faculty of Mathematics and Natural Sciences, University of Helsinki, Helsinki, Finland
- Helsinki University Central Hospital, Helsinki, Finland
| | - Savino Derosa
- Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy
| | | | - Andrea Marzullo
- Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy
| | - Joao Batista Borges
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
- Centre for Human and Applied Physiological Sciences, Faculty of Sciences and Medicine, King’s College London, London, United Kingdom
| | - Sam Bayat
- INSERM UA7, Synchrotron Radiation for Biomedicine (STROBE) Laboratory, Grenoble Alpes University, Amiens, France
| | - Alberto Bravin
- The European Synchrotron Radiation Facility, Grenoble, France
| | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Gaetano Perchiazzi
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
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14
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Xie J, Li H, Zhang H, Zhao X, Shi L, Zhang M, Xiao S, Deng H, Wang K, Yang H, Sun X, Wu G, Ye C, Zhou X. Single breath-hold measurement of pulmonary gas exchange and diffusion in humans with hyperpolarized 129 Xe MR. NMR IN BIOMEDICINE 2019; 32:e4068. [PMID: 30843292 DOI: 10.1002/nbm.4068] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/04/2018] [Accepted: 01/04/2019] [Indexed: 06/09/2023]
Abstract
Pulmonary diseases usually result in changes of the blood-gas exchange function in the early stages. Gas exchange across the respiratory membrane and gas diffusion in the alveoli can be quantified using hyperpolarized 129 Xe MR via chemical shift saturation recovery (CSSR) and diffusion-weighted imaging (DWI), respectively. Generally, CSSR and DWI data have been collected in separate breaths in humans. Unfortunately, the lung inflation level cannot be the exactly same in different breaths, which causes fluctuations in blood-gas exchange and pulmonary microstructure. Here we combine CSSR and DWI obtained with compressed sensing, to evaluate the gas diffusion and exchange function within a single breath-hold in humans. A new parameter, namely the perfusion factor of the respiratory membrane (SVRd/g ), is proposed to evaluate the gas exchange function. Hyperpolarized 129 Xe MR data are compared with pulmonary function tests and computed tomography examinations in healthy young, age-matched control, and chronic obstructive pulmonary disease human cohorts. SVRd/g decreases as the ventilation impairment and emphysema index increase. Our results indicate that the proposed method has the potential to detect the extent of lung parenchyma destruction caused by age and pulmonary diseases, and it would be useful in the early diagnosis of pulmonary diseases in clinical practice.
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Affiliation(s)
- Junshuai Xie
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Haidong Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Huiting Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
| | - Xiuchao Zhao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lei Shi
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ming Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
| | - Sa Xiao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - He Deng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ke Wang
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Hao Yang
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Xianping Sun
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guangyao Wu
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Chaohui Ye
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xin Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
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15
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Bier EA, Robertson SH, Schrank G, Rackley C, Mammarappallil JG, Rajagopal S, McAdams HP, Driehuys B. A protocol for quantifying cardiogenic oscillations in dynamic 129 Xe gas exchange spectroscopy: The effects of idiopathic pulmonary fibrosis. NMR IN BIOMEDICINE 2019; 32:e4029. [PMID: 30457202 PMCID: PMC6447038 DOI: 10.1002/nbm.4029] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 09/14/2018] [Accepted: 09/24/2018] [Indexed: 05/12/2023]
Abstract
The spectral parameters of hyperpolarized 129 Xe exchanging between airspaces, interstitial barrier, and red blood cells (RBCs) are sensitive to pulmonary pathophysiology. This study sought to evaluate whether the dynamics of 129 Xe spectroscopy provide additional insight, with particular focus on quantifying cardiogenic oscillations in the RBC resonance. 129 Xe spectra were dynamically acquired in eight healthy volunteers and nine subjects with idiopathic pulmonary fibrosis (IPF). 129 Xe FIDs were collected every 20 ms (TE = 0.932 ms, 512 points, dwell time = 32 μs, flip angle ≈ 20°) during a 16 s breathing maneuver. The FIDs were pre-processed using the spectral improvement by Fourier thresholding technique (SIFT) and fit in the time domain to determine the airspace, interstitial barrier, and RBC spectral parameters. The RBC and gas resonances were fit to a Lorentzian lineshape, while the barrier was fit to a Voigt lineshape to account for its greater structural heterogeneity. For each complex resonance the amplitude, chemical shift, linewidth(s), and phase were calculated. The time-averaged spectra confirmed that the RBC to barrier amplitude ratio (RBC:barrier ratio) and RBC chemical shift are both reduced in IPF subjects. Their temporal dynamics showed that all three 129 Xe resonances are affected by the breathing maneuver. Most notably, several RBC spectral parameters exhibited prominent oscillations at the cardiac frequency, and their peak-to-peak variation differed between IPF subjects and healthy volunteers. In the IPF cohort, oscillations were more prominent in the RBC amplitude (16.8 ± 5.2 versus 9.7 ± 2.9%; P = 0.008), chemical shift (0.43 ± 0.33 versus 0.083 ± 0.05 ppm; P < 0.001), and phase (7.7 ± 5.6 versus 1.4 ± 0.8°; P < 0.001). Dynamic 129 Xe spectroscopy is a simple and sensitive tool that probes the temporal variability of gas exchange and may prove useful in discerning the underlying causes of its impairment.
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Affiliation(s)
- Elianna A. Bier
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Scott H. Robertson
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
| | - Geoffry Schrank
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
| | - Craig Rackley
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | | | - Sudarshan Rajagopal
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - H. Page McAdams
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
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16
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Knudsen L, Ochs M. The micromechanics of lung alveoli: structure and function of surfactant and tissue components. Histochem Cell Biol 2018; 150:661-676. [PMID: 30390118 PMCID: PMC6267411 DOI: 10.1007/s00418-018-1747-9] [Citation(s) in RCA: 179] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2018] [Indexed: 12/14/2022]
Abstract
The mammalian lung´s structural design is optimized to serve its main function: gas exchange. It takes place in the alveolar region (parenchyma) where air and blood are brought in close proximity over a large surface. Air reaches the alveolar lumen via a conducting airway tree. Blood flows in a capillary network embedded in inter-alveolar septa. The barrier between air and blood consists of a continuous alveolar epithelium (a mosaic of type I and type II alveolar epithelial cells), a continuous capillary endothelium and the connective tissue layer in-between. By virtue of its respiratory movements, the lung has to withstand mechanical challenges throughout life. Alveoli must be protected from over-distension as well as from collapse by inherent stabilizing factors. The mechanical stability of the parenchyma is ensured by two components: a connective tissue fiber network and the surfactant system. The connective tissue fibers form a continuous tensegrity (tension + integrity) backbone consisting of axial, peripheral and septal fibers. Surfactant (surface active agent) is the secretory product of type II alveolar epithelial cells and covers the alveolar epithelium as a biophysically active thin and continuous film. Here, we briefly review the structural components relevant for gas exchange. Then we describe our current understanding of how these components function under normal conditions and how lung injury results in dysfunction of alveolar micromechanics finally leading to lung fibrosis.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany. .,REBIRTH Cluster of Excellence, Hannover, Germany.
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17
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Woods JC, Conradi MS. 3He diffusion MRI in human lungs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 292:90-98. [PMID: 29705031 PMCID: PMC6386180 DOI: 10.1016/j.jmr.2018.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 03/05/2018] [Accepted: 04/11/2018] [Indexed: 06/08/2023]
Abstract
Hyperpolarized 3He gas allows the air spaces of the lungs to be imaged via MRI. Imaging of restricted diffusion is addressed here, which allows the microstructure of the lung to be characterized through the physical restrictions to gas diffusion presented by airway and alveolar walls in the lung. Measurements of the apparent diffusion coefficient (ADC) of 3He at time scales of milliseconds and seconds are compared; measurement of acinar airway sizes by determination of the microscopic anisotropy of diffusion is discussed. This is where Dr. JJH Ackerman's influence was greatest in aiding the formation of the Washington University 3He group, involving early a combination of physicists, radiologists, and surgeons, as the first applications of 3He ADC were to COPD and its destruction/modification of lung microstructure via emphysema. The sensitivity of the method to early COPD is demonstrated, as is its validation by direct comparison to histology. More recently the method has been used broadly in adult and pediatric obstructive lung diseases, from severe asthma to cystic fibrosis to bronchopulmonary dysplasia, a result of premature birth. These applications of the technique are discussed briefly.
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Affiliation(s)
- Jason C Woods
- Center for Pulmonary Imaging Research, Departments of Radiology and Pediatrics (Pulmonary Medicine), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, ML 5033, Cincinnati, OH 45229, USA; Department of Physics, Washington University, One Brookings Drive, CB 1105, St Louis, MO 63130, USA.
| | - Mark S Conradi
- ABQMR, Inc., 2301 Yale Blvd. SE, Suite C2, Albuquerque, NM 87106, USA; Department of Physics, Washington University, One Brookings Drive, CB 1105, St Louis, MO 63130, USA.
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18
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Zhang H, Xie J, Xiao S, Zhao X, Zhang M, Shi L, Wang K, Wu G, Sun X, Ye C, Zhou X. Lung morphometry using hyperpolarized
129
Xe multi‐
b
diffusion
MRI
with compressed sensing in healthy subjects and patients with
COPD. Med Phys 2018; 45:3097-3108. [DOI: 10.1002/mp.12944] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 12/11/2022] Open
Affiliation(s)
- Huiting Zhang
- School of Physics Huazhong University of Science and Technology Wuhan 430074China
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Junshuai Xie
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Sa Xiao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Xiuchao Zhao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Ming Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Lei Shi
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Ke Wang
- Department of Magnetic Resonance Imaging Zhongnan Hospital of Wuhan University Wuhan 430071 China
| | - Guangyao Wu
- Department of Magnetic Resonance Imaging Zhongnan Hospital of Wuhan University Wuhan 430071 China
| | - Xianping Sun
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Chaohui Ye
- School of Physics Huazhong University of Science and Technology Wuhan 430074China
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Xin Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
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19
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McGowan SE, McCoy DM. Neuropilin-1 and platelet-derived growth factor receptors cooperatively regulate intermediate filaments and mesenchymal cell migration during alveolar septation. Am J Physiol Lung Cell Mol Physiol 2018. [PMID: 29543041 DOI: 10.1152/ajplung.00511.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Generation of secondary alveolar septa occurs primarily after birth in humans and is complete in mice postnatally, when mechanical stresses vary as air space pressure oscillates. Alveolar mesenchymal cells deposit elastic fibers, which limit cell strain; although when the elastic fiber network is incomplete, this function is also served by the intracellular cytoskeleton. Intermediate filament proteins support deformation during cell division and migration, which occur during septal elongation. Because platelet-derived growth factor receptor-α (PDGFRα) signaling is essential for alveolar septation, we hypothesized that neuropilin-1 (NRP1) may link PDGFRα to cytoskeletal deformation. During cell migration, NRP1 links receptor tyrosine kinase signaling to cytoskeletal and focal adhesion remodeling. Therefore, we examined the consequences of nrp1 gene deletion in alveolar mesenchymal cells (myofibroblasts and pericytes). NRP1 depletion reduced the proportion of mesenchymal cells that contain nestin and desmin within the subpopulation that lacked PDGFRα but contained PDGFRβ. Desmin was reduced at alveolar entry rings, air spaces were enlarged, and surface area was reduced after NRP1 depletion. PDGFRα and NRP1 colocalized to membrane lipid rafts, which are known to contain Src kinase. NRP1 depletion reduced alveolar mesenchymal cell migration and PDGF-A-mediated activation of Src kinase, which may limit accumulation of desmin at septal tips (alveolar entry rings). Cooperation between NRP1 and PDGF signaling is required for secondary septation, and manipulation of NRP1 could promote alveolar regeneration without producing fibrosis.
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Affiliation(s)
- Stephen E McGowan
- Department of Veterans Affairs Research Service and Department of Internal Medicine, University of Iowa Carver College of Medicine , Iowa City, Iowa
| | - Diann M McCoy
- Department of Veterans Affairs Research Service and Department of Internal Medicine, University of Iowa Carver College of Medicine , Iowa City, Iowa
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20
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Xin Y, Cereda M, Kadlecek S, Emami K, Hamedani H, Duncan I, Rajaei J, Hughes L, Meeder N, Naji J, Profka H, Bolognese BJ, Foley JP, Podolin PL, Rizi RR. Hyperpolarized gas diffusion MRI of biphasic lung inflation in short- and long-term emphysema models. Am J Physiol Lung Cell Mol Physiol 2017; 313:L305-L312. [PMID: 28473321 DOI: 10.1152/ajplung.00048.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 11/22/2022] Open
Abstract
During lung inflation, airspace dimensions are affected nonlinearly by both alveolar expansion and recruitment, potentially confounding the identification of emphysematous lung by hyperpolarized helium-3 diffusion magnetic resonance imaging (HP MRI). This study aimed to characterize lung inflation over a broad range of inflation volume and pressure values in two different models of emphysema, as well as in normal lungs. Elastase-treated rats (n = 7) and healthy controls (n = 7) were imaged with HP MRI. Gradual inflation was achieved by incremental changes to both inflation volume and airway pressure. The apparent diffusion coefficient (ADC) was measured at each level of inflation and fitted to the corresponding airway pressures as the second-order response equation, with minimizing residue (χ2 < 0.001). A biphasic ADC response was detected, with an initial ADC increase followed by a decrease at airway pressures >18 cmH2O. Discrimination between treated and control rats was optimal when airway pressure was intermediate (between 10 and 11 cmH2O). Similar findings were confirmed in mice following long-term exposure to cigarette smoke, where optimal discrimination between treated and healthy mice occurred at a similar airway pressure as in the rats. We subsequently explored the evolution of ADC measured at the intermediate inflation level in mice after prolonged smoke exposure and found a significant increase (P < 0.01) in ADC over time. Our results demonstrate that measuring ADC at intermediate inflation enhances the distinction between healthy and diseased lungs, thereby establishing a model that may improve the diagnostic accuracy of future HP gas diffusion studies.
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Affiliation(s)
- Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ian Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Liam Hughes
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Natalie Meeder
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph Naji
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Joseph P Foley
- Glaxosmithkline, Incorpoarted, King of Prussia, Pennsylvania
| | | | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania;
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21
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Fishman EF, Quirk JD, Sweet SC, Woods JC, Gierada DS, Conradi MS, Siegel MJ, Yablonskiy DA. What makes a good pediatric transplant lung: Insights from in vivo lung morphometry with hyperpolarized 3 He magnetic resonance imaging. Pediatr Transplant 2017; 21:10.1111/petr.12886. [PMID: 28120553 PMCID: PMC5378594 DOI: 10.1111/petr.12886] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/19/2016] [Indexed: 11/26/2022]
Abstract
Obtaining information on transplanted lung microstructure is an important part of the current care for monitoring transplant recipients. However, until now this information was only available from invasive lung biopsy. The objective of this study was to evaluate the use of an innovative non-invasive technique, in vivo lung morphometry with hyperpolarized ³He MRI-to characterize lung microstructure in the pediatric lung transplant population. This technique yields quantitative measurements of acinar airways' (alveolar ducts and sacs) parameters, such as acinar airway radii and alveolar depth. Six pediatric lung transplant recipients with cystic fibrosis underwent in vivo lung morphometry MRI, pulmonary function testing, and quantitative CT. We found a strong correlation between lung lifespan and alveolar depth-patients with more shallow alveoli were likely to have a negative outcome sooner than those with larger alveolar depth. Combining morphometric results with CT, we also determined mean alveolar wall thickness and found substantial increases in this parameter in some patients that negatively correlated with DLCO. In vivo lung morphometry uniquely provides previously unavailable information on lung microstructure that may be predictive of a negative outcome and has a potential to aid in lung selection for transplantation.
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Affiliation(s)
- Emily F. Fishman
- Department of Pediatrics, Washington University, St. Louis, MO, USA
| | - James D. Quirk
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA
| | - Stuart C. Sweet
- Department of Pediatrics, Washington University, St. Louis, MO, USA
| | - Jason C. Woods
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA,Department of Physics, Washington University, St. Louis, MO, USA
| | - David S. Gierada
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA
| | - Mark S. Conradi
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA,Department of Physics, Washington University, St. Louis, MO, USA
| | - Marilyn J. Siegel
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA
| | - Dmitriy A. Yablonskiy
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA,Corresponding Author: Dmitriy A. Yablonskiy, Ph.D., Mallinckrodt Institute of Radiology, Washington University, 4525 Scott Avenue, Campus Box 8227, St. Louis MO, 63110, , Tel.: +1(314) 362-1815, Fax: +1(314) 362-0526
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22
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Yablonskiy DA, Sukstanskii AL, Quirk JD. Diffusion lung imaging with hyperpolarized gas MRI. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3448. [PMID: 26676342 PMCID: PMC4911335 DOI: 10.1002/nbm.3448] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/20/2015] [Accepted: 10/22/2015] [Indexed: 05/28/2023]
Abstract
Lung imaging using conventional 1 H MRI presents great challenges because of the low density of lung tissue, lung motion and very fast lung tissue transverse relaxation (typical T2 * is about 1-2 ms). MRI with hyperpolarized gases (3 He and 129 Xe) provides a valuable alternative because of the very strong signal originating from inhaled gas residing in the lung airspaces and relatively slow gas T2 * relaxation (typical T2 * is about 20-30 ms). However, in vivo human experiments should be performed very rapidly - usually during a single breath-hold. In this review, we describe the recent developments in diffusion lung MRI with hyperpolarized gases. We show that a combination of the results of modeling of gas diffusion in lung airspaces and diffusion measurements with variable diffusion-sensitizing gradients allows the extraction of quantitative information on the lung microstructure at the alveolar level. From an MRI scan of less than 15 s, this approach, called in vivo lung morphometry, allows the provision of quantitative values and spatial distributions of the same physiological parameters as measured by means of 'standard' invasive stereology (mean linear intercept, surface-to-volume ratio, density of alveoli, etc.). In addition, the approach makes it possible to evaluate some advanced Weibel parameters characterizing lung microstructure: average radii of alveolar sacs and ducts, as well as the depth of their alveolar sleeves. Such measurements, providing in vivo information on the integrity of pulmonary acinar airways and their changes in different diseases, are of great importance and interest to a broad range of physiologists and clinicians. We also discuss a new type of experiment based on the in vivo lung morphometry technique combined with quantitative computed tomography measurements, as well as with gradient echo MRI measurements of hyperpolarized gas transverse relaxation in the lung airspaces. Such experiments provide additional information on the blood vessel volume fraction, specific gas volume and length of the acinar airways, and allow the evaluation of lung parenchymal and non-parenchymal tissue. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
| | | | - James D Quirk
- Department of Radiology, Washington University, St. Louis, MO, USA
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Olsson LE, Hockings PD. In Vivo Measurements of T2 Relaxation Time of Mouse Lungs during Inspiration and Expiration. PLoS One 2016; 11:e0166879. [PMID: 27936061 PMCID: PMC5147840 DOI: 10.1371/journal.pone.0166879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 11/04/2016] [Indexed: 11/19/2022] Open
Abstract
Purpose The interest in measurements of magnetic resonance imaging relaxation times, T1, T2, T2*, with intention to characterize healthy and diseased lungs has increased recently. Animal studies play an important role in this context providing models for understanding and linking the measured relaxation time changes to the underlying physiology or disease. The aim of this work was to study how the measured transversal relaxation time (T2) in healthy lungs is affected by normal respiration in mouse. Method T2 of lung was measured in anaesthetized freely breathing mice. Image acquisition was performed on a 4.7 T, Bruker BioSpec with a multi spin-echo sequence (Car-Purcell-Meiboom-Gill) in both end-expiration and end-inspiration. The echo trains consisted of ten echoes of inter echo time 3.5 ms or 4.0 ms. The proton density, T2 and noise floor were fitted to the measured signals of the lung parenchyma with a Levenberg-Marquardt least-squares three-parameter fit. Results T2 in the lungs was longer (p<0.01) at end-expiration (9.7±0.7 ms) than at end-inspiration (9.0±0.8 ms) measured with inter-echo time 3.5 ms. The corresponding relative proton density (lung/muscle tissue) was higher (p<0.001) during end-expiration, (0.61±0.06) than during end-inspiration (0.48±0.05). The ratio of relative proton density at end-inspiration to that at end-expiration was 0.78±0.09. Similar results were found for inter-echo time 4.0 ms and there was no significant difference between the T2 values or proton densities acquired with different interecho times. The T2 value increased linearly (p< 0.001) with proton density. Conclusion The measured T2 in-vivo is affected by diffusion across internal magnetic susceptibility gradients. In the lungs these gradients are modulated by respiration, as verified by calculations. In conclusion the measured T2 was found to be dependent on the size of the alveoli.
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Affiliation(s)
- Lars E. Olsson
- Department of Medical Radiation Physics, Translational Medicine, Lund University, Malmö, Sweden
- * E-mail:
| | - Paul D. Hockings
- Antaros Medical, BioVenture Hub, Mölndal, Sweden
- Medtech West, Chalmers University of Technology, Gothenburg, Sweden
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Hofemeier P, Sznitman J. The role of anisotropic expansion for pulmonary acinar aerosol deposition. J Biomech 2016; 49:3543-3548. [PMID: 27614613 PMCID: PMC5075582 DOI: 10.1016/j.jbiomech.2016.08.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/13/2016] [Accepted: 08/16/2016] [Indexed: 02/02/2023]
Abstract
Lung deformations at the local pulmonary acinar scale are intrinsically anisotropic. Despite progress in imaging modalities, the true heterogeneous nature of acinar expansion during breathing remains controversial, where our understanding of inhaled aerosol deposition still widely emanates from studies under self-similar, isotropic wall motions. Building on recent 3D models of multi-generation acinar networks, we explore in numerical simulations how different hypothesized scenarios of anisotropic expansion influence deposition outcomes of inhaled aerosols in the acinar depths. While the broader range of particles acknowledged to reach the acinar region (dp=0.005-5.0μm) are largely unaffected by the details of anisotropic expansion under tidal breathing, our results suggest nevertheless that anisotropy modulates the deposition sites and fractions for a narrow band of sub-micron particles (dp~0.5-0.75μm), where the fate of aerosols is greatly intertwined with local convective flows. Our findings underscore how intrinsic aerosol motion (i.e. diffusion, sedimentation) undermines the role of anisotropic wall expansion that is often attributed in determining aerosol mixing and acinar deposition.
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Affiliation(s)
- Philipp Hofemeier
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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Stewart NJ, Horn FC, Norquay G, Collier GJ, Yates DP, Lawson R, Marshall H, Wild JM. Reproducibility of quantitative indices of lung function and microstructure from 129 Xe chemical shift saturation recovery (CSSR) MR spectroscopy. Magn Reson Med 2016; 77:2107-2113. [PMID: 27366901 PMCID: PMC5484314 DOI: 10.1002/mrm.26310] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 04/25/2016] [Accepted: 05/24/2016] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the reproducibility of indices of lung microstructure and function derived from 129 Xe chemical shift saturation recovery (CSSR) spectroscopy in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD), and to study the sensitivity of CSSR-derived parameters to pulse sequence design and lung inflation level. METHODS Preliminary data were collected from five volunteers on three occasions, using two implementations of the CSSR sequence. Separately, three volunteers each underwent CSSR at three different lung inflation levels. After analysis of these preliminary data, five COPD patients were scanned on three separate days, and nine age-matched volunteers were scanned three times on one day, to assess reproducibility. RESULTS CSSR-derived alveolar septal thickness (ST) and surface-area-to-volume (S/V) ratio values decreased with lung inflation level (P < 0.001; P = 0.057, respectively). Intra-subject standard deviations of ST were lower than the previously measured differences between volunteers and subjects with interstitial lung disease. The mean coefficient of variation (CV) values of ST were 3.9 ± 1.9% and 6.0 ± 4.5% in volunteers and COPD patients, respectively, similar to CV values for whole-lung carbon monoxide diffusing capacity. The mean CV of S/V in volunteers and patients was 14.1 ± 8.0% and 18.0 ± 19.3%, respectively. CONCLUSION 129 Xe CSSR presents a reproducible method for estimation of alveolar septal thickness. Magn Reson Med 77:2107-2113, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Neil J Stewart
- POLARIS, Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | - Felix C Horn
- POLARIS, Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | - Graham Norquay
- POLARIS, Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | - Guilhem J Collier
- POLARIS, Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | - Denise P Yates
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts, USA
| | - Rod Lawson
- Department of Respiratory Medicine, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Helen Marshall
- POLARIS, Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | - Jim M Wild
- POLARIS, Academic Unit of Radiology, University of Sheffield, Sheffield, UK
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Tabuchi A, Nickles HT, Kim M, Semple JW, Koch E, Brochard L, Slutsky AS, Pries AR, Kuebler WM. Acute Lung Injury Causes Asynchronous Alveolar Ventilation That Can Be Corrected by Individual Sighs. Am J Respir Crit Care Med 2016; 193:396-406. [PMID: 26513710 DOI: 10.1164/rccm.201505-0901oc] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
RATIONALE Improved ventilation strategies have been the mainstay for reducing mortality in acute respiratory distress syndrome. Their unique clinical effectiveness is, however, unmatched by our understanding of the underlying mechanobiology, and their impact on alveolar dynamics and gas exchange remains largely speculative. OBJECTIVES To assess changes in alveolar dynamics and associated effects on local gas exchange in experimental models of acute lung injury (ALI) and their responsiveness to sighs. METHODS Alveolar dynamics and local gas exchange were studied in vivo by darkfield microscopy and multispectral oximetry in experimental murine models of ALI induced by hydrochloric acid, Tween instillation, or in antibody-mediated transfusion-related ALI. MEASUREMENTS AND MAIN RESULTS Independent of injury mode, ALI resulted in asynchronous alveolar ventilation characteristic of alveolar pendelluft, which either spontaneously resolved or progressed to a complete cessation or even inversion of alveolar ventilation. The functional relevance of the latter phenomena was evident as impaired blood oxygenation in juxtaposed lung capillaries. Individual sighs (2 × 10 s at inspiratory plateau pressure of 30 cm H2O) largely restored normal alveolar dynamics and gas exchange in acid-induced ALI, yet not in Tween-induced surfactant depletion. CONCLUSIONS We describe for the first time in detail the different forms and temporal sequence of impaired alveolar dynamics in the acutely injured lung and report the first direct visualization of alveolar pendelluft. Moreover, we identify individual sighs as an effective strategy to restore intact alveolar ventilation by a mechanism independent of alveolar collapse and reopening.
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Affiliation(s)
- Arata Tabuchi
- 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Hannah T Nickles
- 2 Institute of Physiology, Charité-Universitätsmedizin, Berlin, Germany
| | - Michael Kim
- 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
| | - John W Semple
- 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,3 Department of Pharmacology.,4 Department of Medicine.,5 Department of Laboratory Medicine and Pathobiology
| | - Edmund Koch
- 6 Clinical Sensoring and Monitoring, Department of Anesthesiology and Intensive Care Medicine, Medical Faculty of the Technical University, Dresden, Germany; and
| | - Laurent Brochard
- 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,7 Interdepartmental Division of Critical Care Medicine
| | - Arthur S Slutsky
- 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,7 Interdepartmental Division of Critical Care Medicine
| | - Axel R Pries
- 2 Institute of Physiology, Charité-Universitätsmedizin, Berlin, Germany
| | - Wolfgang M Kuebler
- 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,2 Institute of Physiology, Charité-Universitätsmedizin, Berlin, Germany.,8 Department of Surgery, and.,9 Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,10 German Heart Institute, Berlin, Germany
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Capaldi DPI, Zha N, Guo F, Pike D, McCormack DG, Kirby M, Parraga G. Pulmonary Imaging Biomarkers of Gas Trapping and Emphysema in COPD:3He MR Imaging and CT Parametric Response Maps. Radiology 2016; 279:597-608. [DOI: 10.1148/radiol.2015151484] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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28
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Abstract
Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.
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Affiliation(s)
- Connie C.W. Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Dallas M. Hyde
- California National Primate Research Center, University of California at Davis, Davis, California, USA
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Kruger SJ, Nagle SK, Couch MJ, Ohno Y, Albert M, Fain SB. Functional imaging of the lungs with gas agents. J Magn Reson Imaging 2016; 43:295-315. [PMID: 26218920 PMCID: PMC4733870 DOI: 10.1002/jmri.25002] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/26/2015] [Indexed: 12/22/2022] Open
Abstract
This review focuses on the state-of-the-art of the three major classes of gas contrast agents used in magnetic resonance imaging (MRI)-hyperpolarized (HP) gas, molecular oxygen, and fluorinated gas--and their application to clinical pulmonary research. During the past several years there has been accelerated development of pulmonary MRI. This has been driven in part by concerns regarding ionizing radiation using multidetector computed tomography (CT). However, MRI also offers capabilities for fast multispectral and functional imaging using gas agents that are not technically feasible with CT. Recent improvements in gradient performance and radial acquisition methods using ultrashort echo time (UTE) have contributed to advances in these functional pulmonary MRI techniques. The relative strengths and weaknesses of the main functional imaging methods and gas agents are compared and applications to measures of ventilation, diffusion, and gas exchange are presented. Functional lung MRI methods using these gas agents are improving our understanding of a wide range of chronic lung diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis in both adults and children.
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Affiliation(s)
- Stanley J. Kruger
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
| | - Scott K. Nagle
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Pediatrics, University of Wisconsin – Madison, WI, U.S.A
| | - Marcus J. Couch
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Biotechnology Program, Lakehead University, Thunder Bay, ON, Canada
| | - Yoshiharu Ohno
- Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Mitchell Albert
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Department of Chemistry, Lakehead University, Thunder Bay, ON, Canada
| | - Sean B. Fain
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Biomedical Engineering, University of Wisconsin – Madison, WI, U.S.A
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30
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Thomen RP, Quirk JD, Roach D, Egan‐Rojas T, Ruppert K, Yusen RD, Altes TA, Yablonskiy DA, Woods JC. Direct comparison of
129
X
e diffusion measurements with quantitative histology in human lungs. Magn Reson Med 2016; 77:265-272. [DOI: 10.1002/mrm.26120] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/13/2015] [Accepted: 12/17/2015] [Indexed: 12/22/2022]
Affiliation(s)
- Robert P. Thomen
- Center for Pulmonary Imaging ResearchCincinnati Children's Hospital Medical CenterCincinnati OH USA
- Department of PhysicsWashington University in St. LouisSt. Louis MO USA
| | - James D. Quirk
- Mallinckrodt Institute of RadiologyWashington University School of MedicineSt. Louis MO USA
| | - David Roach
- Center for Pulmonary Imaging ResearchCincinnati Children's Hospital Medical CenterCincinnati OH USA
| | - Tiffany Egan‐Rojas
- Center for Pulmonary Imaging ResearchCincinnati Children's Hospital Medical CenterCincinnati OH USA
| | - Kai Ruppert
- Center for Pulmonary Imaging ResearchCincinnati Children's Hospital Medical CenterCincinnati OH USA
| | - Roger D. Yusen
- Division of Pulmonary and Critical Care MedicineWashington University School of MedicineSt. Louis MO USA
| | | | - Dmitriy A. Yablonskiy
- Mallinckrodt Institute of RadiologyWashington University School of MedicineSt. Louis MO USA
| | - Jason C. Woods
- Center for Pulmonary Imaging ResearchCincinnati Children's Hospital Medical CenterCincinnati OH USA
- Department of PhysicsWashington University in St. LouisSt. Louis MO USA
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31
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Yablonskiy DA, Sukstanskii AL, Quirk JD, Woods JC, Conradi MS. Probing lung microstructure with hyperpolarized noble gas diffusion MRI: theoretical models and experimental results. Magn Reson Med 2016; 71:486-505. [PMID: 23554008 DOI: 10.1002/mrm.24729] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The introduction of hyperpolarized gases ((3)He and (129)Xe) has opened the door to applications for which gaseous agents are uniquely suited-lung MRI. One of the pulmonary applications, diffusion MRI, relies on measuring Brownian motion of inhaled hyperpolarized gas atoms diffusing in lung airspaces. In this article we provide an overview of the theoretical ideas behind hyperpolarized gas diffusion MRI and the results obtained over the decade-long research. We describe a simple technique based on measuring gas apparent diffusion coefficient (ADC) and an advanced technique, in vivo lung morphometry, that quantifies lung microstructure both in terms of Weibel parameters (acinar airways radii and alveolar depth) and standard metrics (mean linear intercept, surface-to-volume ratio, and alveolar density) that are widely used by lung researchers but were previously available only from invasive lung biopsy. This technique has the ability to provide unique three-dimensional tomographic information on lung microstructure from a less than 15 s MRI scan with results that are in good agreement with direct histological measurements. These safe and sensitive diffusion measurements improve our understanding of lung structure and functioning in health and disease, providing a platform for monitoring the efficacy of therapeutic interventions in clinical trials.
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Quirk JD, Sukstanskii AL, Woods JC, Lutey BA, Conradi MS, Gierada DS, Yusen RD, Castro M, Yablonskiy DA. Experimental evidence of age-related adaptive changes in human acinar airways. J Appl Physiol (1985) 2015; 120:159-65. [PMID: 26542518 DOI: 10.1152/japplphysiol.00541.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/01/2015] [Indexed: 11/22/2022] Open
Abstract
The progressive decline of lung function with aging is associated with changes in lung structure at all levels, from conducting airways to acinar airways (alveolar ducts and sacs). While information on conducting airways is becoming available from computed tomography, in vivo information on the acinar airways is not conventionally available, even though acini occupy 95% of lung volume and serve as major gas exchange units of the lung. The objectives of this study are to measure morphometric parameters of lung acinar airways in living adult humans over a broad range of ages by using an innovative MRI-based technique, in vivo lung morphometry with hyperpolarized (3)He gas, and to determine the influence of age-related differences in acinar airway morphometry on lung function. Pulmonary function tests and MRI with hyperpolarized (3)He gas were performed on 24 healthy nonsmokers aged 19-71 years. The most significant age-related difference across this population was a 27% loss of alveolar depth, h, leading to a 46% increased acinar airway lumen radius, hence, decreased resistance to acinar air transport. Importantly, the data show a negative correlation between h and the pulmonary function measures forced expiratory volume in 1 s and forced vital capacity. In vivo lung morphometry provides unique information on age-related changes in lung microstructure and their influence on lung function. We hypothesize that the observed reduction of alveolar depth in subjects with advanced aging represents a remodeling process that might be a compensatory mechanism, without which the pulmonary functional decline due to other biological factors with advancing age would be significantly larger.
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Affiliation(s)
- James D Quirk
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Alexander L Sukstanskii
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Jason C Woods
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Physics, Washington University, St. Louis, Missouri
| | - Barbara A Lutey
- Department of Internal Medicine, Division of Medical Education, Washington University School of Medicine, St. Louis, Missouri; and
| | - Mark S Conradi
- Department of Physics, Washington University, St. Louis, Missouri
| | - David S Gierada
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Roger D Yusen
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Mario Castro
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Dmitriy A Yablonskiy
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri;
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Characterization of acinar airspace involvement in asthmatic patients by using inert gas washout and hyperpolarized (3)helium magnetic resonance. J Allergy Clin Immunol 2015; 137:417-25. [PMID: 26242298 DOI: 10.1016/j.jaci.2015.06.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 05/29/2015] [Accepted: 06/17/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND The multiple-breath inert gas washout parameter acinar ventilation heterogeneity (Sacin) is thought to be a marker of acinar airway involvement but has not been validated by using quantitative imaging techniques in asthmatic patients. OBJECTIVE We aimed to use hyperpolarized (3)He diffusion magnetic resonance at multiple diffusion timescales and quantitative computed tomographic (CT) densitometry to determine the nature of acinar airway involvement in asthmatic patients. METHODS Thirty-seven patients with asthma and 17 age-matched healthy control subjects underwent spirometry, body plethysmography, multiple-breath inert gas washout (with the tracer gas sulfur hexafluoride), and hyperpolarized (3)He diffusion magnetic resonance. A subset of asthmatic patients (n = 27) underwent quantitative CT densitometry. RESULTS Ninety-four percent (16/17) of patients with an increased Sacin had Global Initiative for Asthma treatment step 4 to 5 asthma, and 13 of 17 had refractory disease. The apparent diffusion coefficient (ADC) of (3)He at 1 second was significantly higher in patients with Sacin-high asthma compared with that in healthy control subjects (0.024 vs 0.017, P < .05). Sacin correlated strongly with ADCs at 1 second (R = 0.65, P < .001) but weakly with ADCs at 13 ms (R = 0.38, P < .05). ADCs at both 13 ms and 1 second correlated strongly with the mean lung density expiratory/inspiratory ratio, a CT marker of expiratory air trapping (R = 0.77, P < .0001 for ADCs at 13 ms; R = 0.72, P < .001 for ADCs at 1 second). CONCLUSION Sacin is associated with alterations in long-range diffusion within the acinar airways and gas trapping. The precise anatomic nature and mechanistic role in patients with severe asthma requires further evaluation.
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34
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McLaughlin RA, Noble PB, Sampson DD. Optical coherence tomography in respiratory science and medicine: from airways to alveoli. Physiology (Bethesda) 2015; 29:369-80. [PMID: 25180266 DOI: 10.1152/physiol.00002.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Optical coherence tomography is a rapidly maturing optical imaging technology, enabling study of the in vivo structure of lung tissue at a scale of tens of micrometers. It has been used to assess the layered structure of airway walls, quantify both airway lumen caliber and compliance, and image individual alveoli. This article provides an overview of the technology and reviews its capability to provide new insights into respiratory disease.
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Affiliation(s)
- Robert A McLaughlin
- Optical & Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Perth, Australia;
| | - Peter B Noble
- School of Anatomy, Physiology & Human Biology, and Centre for Neonatal Research & Education, School of Paediatrics and Child Health, The University of Western Australia, Crawley, Australia; and
| | - David D Sampson
- Optical & Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Perth, Australia; Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, Perth, Australia
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35
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Walkup LL, Woods JC. Translational applications of hyperpolarized 3He and 129Xe. NMR IN BIOMEDICINE 2014; 27:1429-1438. [PMID: 24953709 DOI: 10.1002/nbm.3151] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/07/2014] [Accepted: 05/19/2014] [Indexed: 06/03/2023]
Abstract
Clinical magnetic resonance imaging of the lung is technologically challenging, yet over the past two decades hyperpolarized noble gas ((3)He and (129)Xe) imaging has demonstrated the ability to measure multiple pulmonary functional biomarkers. There is a growing need for non-ionizing, non-invasive imaging techniques due to increased concern about cancer risk from ionizing radiation, but the translation of hyperpolarized gas imaging to the pulmonary clinic has been stunted by limited access to the technology. New developments may open doors to greater access and more translation to clinical studies. Here we briefly review a few translational applications of hyperpolarized gas MRI in the contexts of ventilation, diffusion, and dissolved-phase imaging, as well as comparing and contrasting (3)He and (129)Xe gases for these applications. Simple static ventilation MRI reveals regions of the lung not participating in normal ventilation, and these defects have been observed in many pulmonary diseases. Biomarkers related to airspace size and connectivity can be quantified by apparent diffusion coefficient measurements of hyperpolarized gas, and have been shown to be more sensitive to small changes in lung morphology than standard clinical pulmonary functional tests and have been validated by quantitative histology. Parameters related to gas uptake and exchange and lung tissue density can be determined using (129)Xe dissolved-phase MRI. In most cases functional biomarkers can be determined via MRI of either gas, but for some applications one gas may be preferred, such as (3)He for long-range diffusion measurements and (129)Xe for dissolved-phase imaging. Greater access to hyperpolarized gas imaging coupled with newly developing therapeutics makes pulmonary medicine poised for a potential revolution, further adding to the prospects of personalized medicine already evidenced by advancements in molecular biology. Hyperpolarized gas researchers have the opportunity to contribute to this revolution, particularly if greater clinical application of hyperpolarized gas imaging is realized.
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Affiliation(s)
- Laura L Walkup
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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36
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Cereda M, Xin Y, Kadlecek S, Hamedani H, Rajaei J, Clapp J, Rizi RR. Hyperpolarized gas diffusion MRI for the study of atelectasis and acute respiratory distress syndrome. NMR IN BIOMEDICINE 2014; 27:1468-78. [PMID: 24920074 PMCID: PMC4232982 DOI: 10.1002/nbm.3136] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/03/2014] [Accepted: 04/21/2014] [Indexed: 06/03/2023]
Abstract
Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury, which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of computed tomography, positron emission tomography, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized (HP) gas MRI--a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces--is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of (3) He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces, (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces, and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation.
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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
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Jennia Rajaei
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Justin Clapp
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahim R. Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
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37
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Endomicroscopic analysis of time- and pressure-dependent area of subpleural alveoli in mechanically ventilated rats. Respir Physiol Neurobiol 2014; 203:1-8. [DOI: 10.1016/j.resp.2014.08.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/29/2014] [Accepted: 08/04/2014] [Indexed: 11/18/2022]
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38
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Dai Z, Peng Y, Mansy HA, Sandler RH, Royston TJ. Comparison of Poroviscoelastic Models for Sound and Vibration in the Lungs. JOURNAL OF VIBRATION AND ACOUSTICS 2014; 136:0510121-5101211. [PMID: 25278740 PMCID: PMC4112928 DOI: 10.1115/1.4026436] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/18/2013] [Indexed: 05/23/2023]
Abstract
Noninvasive measurement of mechanical wave motion (sound and vibration) in the lungs may be of diagnostic value, as it can provide information about the mechanical properties of the lungs, which in turn are affected by disease and injury. In this study, two previously derived theoretical models of the vibroacoustic behavior of the lung parenchyma are compared: (1) a Biot theory of poroviscoelasticity and (2) an effective medium theory for compression wave behavior (also known as a "bubble swarm" model). A fractional derivative formulation of shear viscoelasticity is integrated into both models. A measurable "fast" compression wave speed predicted by the Biot theory formulation has a significant frequency dependence that is not predicted by the effective medium theory. Biot theory also predicts a slow compression wave. The experimentally measured fast compression wave speed and attenuation in a pig lung ex vivo model agreed well with the Biot theory. To obtain the parameters for the Biot theory prediction, the following experiments were undertaken: quasistatic mechanical indentation measurements were performed to estimate the lung static shear modulus; surface wave measurements were performed to estimate lung tissue shear viscoelasticity; and flow permeability was measured on dried lung specimens. This study suggests that the Biot theory may provide a more robust and accurate model than the effective medium theory for wave propagation in the lungs over a wider frequency range.
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Affiliation(s)
- Zoujun Dai
- University of Illinois at Chicago , Chicago, IL 60607
| | - Ying Peng
- University of Illinois at Chicago , Chicago, IL 60607
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39
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Perchiazzi G, Rylander C, Derosa S, Pellegrini M, Pitagora L, Polieri D, Vena A, Tannoia A, Fiore T, Hedenstierna G. Regional distribution of lung compliance by image analysis of computed tomograms. Respir Physiol Neurobiol 2014; 201:60-70. [PMID: 25026158 DOI: 10.1016/j.resp.2014.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/01/2014] [Accepted: 07/02/2014] [Indexed: 10/25/2022]
Abstract
Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. CL and the sum of positive voxel compliances from CT were linearly correlated; negative compliance areas were found. A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.
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Affiliation(s)
- Gaetano Perchiazzi
- Emergency and Organ Transplant, Bari University, Bari, Italy; Medical Sciences - Clinical Physiology, Uppsala University, Uppsala, Sweden.
| | - Christian Rylander
- Anaesthesia and Intensive Care Medicine, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Savino Derosa
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | | | | | - Debora Polieri
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Antonio Vena
- Intensive Care Unit, SS Annunziata Hospital, Taranto, Italy
| | - Angela Tannoia
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Tommaso Fiore
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Göran Hedenstierna
- Medical Sciences - Clinical Physiology, Uppsala University, Uppsala, Sweden
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40
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Cereda M, Xin Y, Emami K, Huang J, Rajaei J, Profka H, Han B, Mongkolwisetwara P, Kadlecek S, Kuzma NN, Pickup S, Kavanagh BP, Deutschman CS, Rizi RR. Positive end-expiratory pressure increments during anesthesia in normal lung result in hysteresis and greater numbers of smaller aerated airspaces. Anesthesiology 2013; 119:1402-9. [PMID: 24025616 PMCID: PMC3987989 DOI: 10.1097/aln.0b013e3182a9b0c1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Although it is recognized that pulmonary hysteresis can influence the effects of positive end-expiratory pressure (PEEP), the extent to which expansion of previously opened (vs. newly opening) peripheral airspaces contribute to increased lung volume is unknown. METHODS Following a recruitment maneuver, rats were ventilated with constant tidal volumes and imaged during ascending and descending ramps of PEEP. RESULTS The authors estimated peripheral airspace dimensions by measuring the apparent diffusion coefficient of He in 10 rats. In a separate group (n = 5) undergoing a similar protocol, the authors used computerized tomography to quantify lung volume. Hysteresis was confirmed by larger end-inspiratory lung volume (mean ± SD; all PEEP levels included): 8.4 ± 2.8 versus 6.8 ± 2.0 ml (P < 0.001) and dynamic compliance: 0.52 ± 0.12 versus 0.42 ± 0.09 ml/cm H2O (P < 0.001) during descending versus ascending PEEP ramps. Apparent diffusion coefficient increased with PEEP, but it was smaller during the descending versus ascending ramps for corresponding levels of PEEP: 0.168 ± 0.019 versus 0.183 ± 0.019 cm/s (P < 0.001). Apparent diffusion coefficient was smaller in the posterior versus anterior lung regions, but the effect of PEEP and hysteresis on apparent diffusion coefficient was greater in the posterior regions. CONCLUSIONS The authors' study results suggest that in healthy lungs, larger lung volumes due to hysteresis are associated with smaller individual airspaces. This may be explained by opening of previously nonaerated peripheral airspaces rather than expansion of those already aerated. Setting PEEP on a descending ramp may minimize distension of individual airspaces.
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Affiliation(s)
- Maurizio Cereda
- Assistant Professor, Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yi Xin
- Research Specialist, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kiarash Emami
- Project Manager, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jessie Huang
- Student, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jennia Rajaei
- Student, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Harrilla Profka
- Research Specialist, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Biao Han
- Research Specialist, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Stephen Kadlecek
- Research Assistant Professor, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nicholas N. Kuzma
- Research Assistant Professor, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephen Pickup
- Technical Director, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Brian P. Kavanagh
- Professor, Departments of Critical Care Medicine and Anesthesia, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Clifford S. Deutschman
- Professor, Department of Anesthesiology and Critical Care and Stavropoulos Sepsis Research Program, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rahim R. Rizi
- Professor, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
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41
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Namati E, Warger WC, Unglert CI, Eckert JE, Hostens J, Bouma BE, Tearney GJ. Four-dimensional visualization of subpleural alveolar dynamics in vivo during uninterrupted mechanical ventilation of living swine. BIOMEDICAL OPTICS EXPRESS 2013; 4:2492-506. [PMID: 24298409 PMCID: PMC3829543 DOI: 10.1364/boe.4.002492] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/24/2013] [Accepted: 08/28/2013] [Indexed: 05/04/2023]
Abstract
Pulmonary alveoli have been studied for many years, yet no unifying hypothesis exists for their dynamic mechanics during respiration due to their miniature size (100-300 μm dimater in humans) and constant motion, which prevent standard imaging techniques from visualizing four-dimensional dynamics of individual alveoli in vivo. Here we report a new platform to image the first layer of air-filled subpleural alveoli through the use of a lightweight optical frequency domain imaging (OFDI) probe that can be placed upon the pleura to move with the lung over the complete range of respiratory motion. This device enables in-vivo acquisition of four-dimensional microscopic images of alveolar airspaces (alveoli and ducts), within the same field of view, during continuous ventilation without restricting the motion or modifying the structure of the alveoli. Results from an exploratory study including three live swine suggest that subpleural alveolar air spaces are best fit with a uniform expansion (r (2) = 0.98) over a recruitment model (r (2) = 0.72). Simultaneously, however, the percentage change in volume shows heterogeneous alveolar expansion within just a 1 mm x 1 mm field of view. These results signify the importance of four-dimensional imaging tools, such as the device presented here. Quantification of the dynamic response of the lung during ventilation may help create more accurate modeling techniques and move toward a more complete understanding of alveolar mechanics.
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Affiliation(s)
- Eman Namati
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Co-first authors. These authors contributed equally to this work
| | - William C. Warger
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Co-first authors. These authors contributed equally to this work
| | - Carolin I. Unglert
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Air Liquide Centre de Recherche Claude-Delorme, Medical Gases Group, 1 Chemin de la Porte des Loges, Les-Loges-en-Josas, France
| | - Jocelyn E. Eckert
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
| | | | - Brett E. Bouma
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Guillermo J. Tearney
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114 USA
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42
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Carnibella RP, Kitchen MJ, Fouras A. Decoding the structure of granular and porous materials from speckled phase contrast X-ray images. OPTICS EXPRESS 2013; 21:19153-62. [PMID: 23938830 DOI: 10.1364/oe.21.019153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Imaging techniques for studying the structure of opaque, granular and porous materials are limited by temporal resolution and radiation dose. We present a technique for characterising the structure of such materials by decoding three dimensional structural information from single, propagation based phase contrast X-ray images. We demonstrate the technique by measuring the distribution of diameters of glass microspheres in packed samples. We also present synthetic data, which shows that our inverse method is stable and that accuracy is improved by phase contrast X-ray imaging. Compared to computed tomography, our technique has superior temporal resolution and lower radiation dose.
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Affiliation(s)
- R P Carnibella
- Department of Mechanical Engineering, Monash University, Melbourne, 3800, Australia.
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43
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Weibel ER, Nieman GF, Gatto LA, Frazer DG, Schittny JC, Woods JC, Conradi MS, Yablonskiy DA. Commentaries on viewpoint: unresolved mysteries. J Appl Physiol (1985) 2013; 113:1948-9. [PMID: 23243296 DOI: 10.1152/japplphysiol.01203.2012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Ewald R Weibel
- Emeritus Professor Institute of Anatomy, University of Berne
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44
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Sera T, Yokota H, Tanaka G, Uesugi K, Yagi N, Schroter RC. Murine pulmonary acinar mechanics during quasi-static inflation using synchrotron refraction-enhanced computed tomography. J Appl Physiol (1985) 2013; 115:219-28. [PMID: 23661619 DOI: 10.1152/japplphysiol.01105.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We visualized pulmonary acini in the core regions of the mouse lung in situ using synchrotron refraction-enhanced computed tomography (CT) and evaluated their kinematics during quasi-static inflation. This CT system (with a cube voxel of 2.8 μm) allows excellent visualization of not just the conducting airways, but also the alveolar ducts and sacs, and tracking of the acinar shape and its deformation during inflation. The kinematics of individual alveoli and alveolar clusters with a group of terminal alveoli is influenced not only by the connecting alveolar duct and alveoli, but also by the neighboring structures. Acinar volume was not a linear function of lung volume. The alveolar duct diameter changed dramatically during inflation at low pressures and remained relatively constant above an airway pressure of ∼8 cmH2O during inflation. The ratio of acinar surface area to acinar volume indicates that acinar distension during low-pressure inflation differed from that during inflation over a higher pressure range; in particular, acinar deformation was accordion-like during low-pressure inflation. These results indicated that the alveoli and duct expand differently as total acinar volume increases and that the alveolar duct may expand predominantly during low-pressure inflation. Our findings suggest that acinar deformation in the core regions of the lung is complex and heterogeneous.
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Affiliation(s)
- Toshihiro Sera
- Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, Japan.
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45
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Affiliation(s)
- Ewald R Weibel
- Institute of Anatomy, Baltzerstrasse 2, CH-3000 Bern, Switzerland.
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46
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Burke W. Why do we yawn? Health (London) 2013. [DOI: 10.4236/health.2013.510213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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47
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Affiliation(s)
- Gerald C Smaldone
- Pulmonary, Critical Care and Sleep Medicine, Stony Brook University Medical Center, Stony Brook, New York, USA
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48
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49
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McLaughlin RA, Yang X, Quirk BC, Lorenser D, Kirk RW, Noble PB, Sampson DD. Static and dynamic imaging of alveoli using optical coherence tomography needle probes. J Appl Physiol (1985) 2012; 113:967-74. [DOI: 10.1152/japplphysiol.00051.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Imaging of alveoli in situ has for the most part been infeasible due to the high resolution required to discern individual alveoli and limited access to alveoli beneath the lung surface. In this study, we present a novel technique to image alveoli using optical coherence tomography (OCT). We propose the use of OCT needle probes, where the distal imaging probe has been miniaturized and encased within a hypodermic needle (as small as 30-gauge, outer diameter 310 μm), allowing insertion deep within the lung tissue with minimal tissue distortion. Such probes enable imaging at a resolution of ∼12 μm within a three-dimensional cylindrical field of view with diameter ∼1.5 mm centered on the needle tip. The imaging technique is demonstrated on excised lungs from three different species: adult rats, fetal sheep, and adult pigs. OCT needle probes were used to image alveoli, small bronchioles, and blood vessels, and results were matched to histological sections. We also present the first dynamic OCT images acquired with an OCT needle probe, allowing tracking of individual alveoli during simulated cyclical lung inflation and deflation.
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Affiliation(s)
- Robert A. McLaughlin
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Xiaojie Yang
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Bryden C. Quirk
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Dirk Lorenser
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Rodney W. Kirk
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
| | - Peter B. Noble
- Centre for Neonatal Research and Education, School of Women's and Infants' Health, University of Western Australia, Crawley, Western Australia, Australia; and
| | - David D. Sampson
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, Western Australia, Australia
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley Western Australia, Australia
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50
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Abstract
A 33-year-old woman underwent a right-sided pneumonectomy in 1995 for treatment of a lung adenocarcinoma. As expected, there was an abrupt decrease in her vital capacity, but unexpectedly, it increased during the subsequent 15 years. Serial computed tomographic (CT) scans showed progressive enlargement of the remaining left lung and an increase in tissue density. Magnetic resonance imaging (MRI) with the use of hyperpolarized helium-3 gas showed overall acinar-airway dimensions that were consistent with an increase in the alveolar number rather than the enlargement of existing alveoli, but the alveoli in the growing lung were shallower than in normal lungs. This study provides evidence that new lung growth can occur in an adult human.
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Affiliation(s)
- James P Butler
- Division of Sleep Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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