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Inhaled Gas Magnetic Resonance Imaging: Advances, Applications, Limitations, and New Frontiers. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00013-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Hopkins SR. Ventilation/Perfusion Relationships and Gas Exchange: Measurement Approaches. Compr Physiol 2020; 10:1155-1205. [PMID: 32941684 DOI: 10.1002/cphy.c180042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Ventilation-perfusion ( V ˙ A / Q ˙ ) matching, the regional matching of the flow of fresh gas to flow of deoxygenated capillary blood, is the most important mechanism affecting the efficiency of pulmonary gas exchange. This article discusses the measurement of V ˙ A / Q ˙ matching with three broad classes of techniques: (i) those based in gas exchange, such as the multiple inert gas elimination technique (MIGET); (ii) those derived from imaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT), and electrical impedance tomography (EIT); and (iii) fluorescent and radiolabeled microspheres. The focus is on the physiological basis of these techniques that provide quantitative information for research purposes rather than qualitative measurements that are used clinically. The fundamental equations of pulmonary gas exchange are first reviewed to lay the foundation for the gas exchange techniques and some of the imaging applications. The physiological considerations for each of the techniques along with advantages and disadvantages are briefly discussed. © 2020 American Physiological Society. Compr Physiol 10:1155-1205, 2020.
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Affiliation(s)
- Susan R Hopkins
- Departments of Medicine and Radiology, University of California, San Diego, California, USA
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Keeley TP, Mann GE. Defining Physiological Normoxia for Improved Translation of Cell Physiology to Animal Models and Humans. Physiol Rev 2019; 99:161-234. [PMID: 30354965 DOI: 10.1152/physrev.00041.2017] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extensive oxygen gradient between the air we breathe (Po2 ~21 kPa) and its ultimate distribution within mitochondria (as low as ~0.5-1 kPa) is testament to the efforts expended in limiting its inherent toxicity. It has long been recognized that cell culture undertaken under room air conditions falls short of replicating this protection in vitro. Despite this, difficulty in accurately determining the appropriate O2 levels in which to culture cells, coupled with a lack of the technology to replicate and maintain a physiological O2 environment in vitro, has hindered addressing this issue thus far. In this review, we aim to address the current understanding of tissue Po2 distribution in vivo and summarize the attempts made to replicate these conditions in vitro. The state-of-the-art techniques employed to accurately determine O2 levels, as well as the issues associated with reproducing physiological O2 levels in vitro, are also critically reviewed. We aim to provide the framework for researchers to undertake cell culture under O2 levels relevant to specific tissues and organs. We envisage that this review will facilitate a paradigm shift, enabling translation of findings under physiological conditions in vitro to disease pathology and the design of novel therapeutics.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
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Möller HE. Extracting Regional Oxygen Tension from Multibreath Wash-in3He MR Imaging. Radiology 2017; 285:1056-1057. [DOI: 10.1148/radiol.2017171576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Harald E. Möller
- Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr 1A, 04103 Leipzig, Germany
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Hamedani H, Kadlecek S, Xin Y, Siddiqui S, Gatens H, Naji J, Ishii M, Cereda M, Rossman M, Rizi R. A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized 3 He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping. Magn Reson Med 2017; 78:611-624. [PMID: 27734519 PMCID: PMC5391315 DOI: 10.1002/mrm.26401] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 08/03/2016] [Accepted: 08/08/2016] [Indexed: 01/06/2023]
Abstract
PURPOSE To present a method for simultaneous acquisition of alveolar oxygen tension (PA O2 ), specific ventilation (SV), and apparent diffusion coefficient (ADC) of hyperpolarized (HP) gas in the human lung, allowing reinterpretation of the PA O2 and SV maps to produce a map of oxygen uptake (R). METHOD An imaging scheme was designed with a series of identical normoxic HP gas wash-in breaths to measure ADC, SV, PA O2 , and R in less than 2 min. Signal dynamics were fit to an iterative recursive model that regionally solved for these parameters. This measurement was successfully performed in 12 subjects classified in three healthy, smoker, and chronic obstructive pulmonary disease (COPD) cohorts. RESULTS The overall whole lung ADC, SV, PA O2 , and R in healthy, smoker, and COPD subjects was 0.20 ± 0.03 cm2 /s, 0.39 ± 0.06,113 ± 2 Torr, and 1.55 ± 0.35 Torr/s, respectively, in healthy subjects; 0.21 ± 0.03 cm2 /s, 0.33 ± 0.06, 115.9 ± 4 Torr, and 0.97 ± 0.2 Torr/s, respectively, in smokers; and 0.25 ± 0.06 cm2 /s, 0.23 ± 0.08, 114.8 ± 6.0Torr, and 0.94 ± 0.12 Torr/s, respectively, in subjects with COPD. Hetrogeneity of SV, PA O2 , and R were indicators of both smoking-related changes and disease, and the severity of the disease correlated with the degree of this heterogeneity. Subjects with symptoms showed reduced oxygen uptake and specific ventilation. CONCLUSION High-resolution, nearly coregistered and quantitative measures of lung function and structure were obtained with less than 1 L of HP gas. This hybrid multibreath technique produced measures of lung function that revealed clear differences among the cohorts and subjects and were confirmed by correlations with global lung measurements. Magn Reson Med 78:611-624, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Sarmad Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Heather Gatens
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Joseph Naji
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Masaru Ishii
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
- Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, United States
| | - Milton Rossman
- Pulmonary, Allergy and Critical Care Division, University of Pennsylvania, Philadelphia, PA, United States
| | - Rahim Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
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Hahn AD, Cadman RV, Sorkness RL, Jarjour NN, Nagle SK, Fain SB. Redistribution of inhaled hyperpolarized 3He gas during breath-hold differs by asthma severity. J Appl Physiol (1985) 2015; 120:526-36. [PMID: 26635346 DOI: 10.1152/japplphysiol.00197.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 11/30/2015] [Indexed: 11/22/2022] Open
Abstract
The purpose of this work was to quantify the redistribution of ventilation-weighted signal in the lungs of asthmatic subjects during a breath-hold using high temporal-spatial resolution hyperpolarized (HP) He-3 MRI. HP He-3 MRI was used to obtain time-resolved, volumetric images of lung ventilation during breath-hold in 39 human subjects classified as either healthy/nondiseased (n = 14), mild-to-moderate asthmatic (n = 17), or severely asthmatic (n = 8). Signals were normalized to a standard lung volume, so that voxels within the lung from all 39 subjects could be analyzed as a group to increase statistical power and enable semiautomated classification of voxels into 1 of 5 ventilation level categories (ranging from defect to hyperintense). End-inspiratory ventilation distribution and temporal rates of mean signal change for each of the five ventilation categories were compared using ANOVA. Time rates of signal change were hypothesized to represent underlying gas redistribution processes, potentially influenced by disease. We found that mild-to-moderate asthmatic subjects showed the greatest rate of signal change, even though those with severe asthma had the greatest end-inspiration ventilation heterogeneity. The observed results support the existence of local differences in airway resistances associated with the different obstructive patterns in the lungs for severe vs. mild-to-moderate asthmatic subjects.
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Affiliation(s)
- Andrew D Hahn
- Department of Medical Physics, University of Wisconsin-Madison, Wisconsin
| | - Robert V Cadman
- Department of Medical Physics, University of Wisconsin-Madison, Wisconsin
| | - Ronald L Sorkness
- School of Pharmacy, University of Wisconsin-Madison, Wisconsin; Department of Medicine, University of Wisconsin-Madison, Wisconsin; Departments of Pediatrics and Biomedical Engineering; University of Wisconsin-Madison, Wisconsin
| | - Nizar N Jarjour
- Department of Medicine, University of Wisconsin-Madison, Wisconsin
| | - Scott K Nagle
- Department of Medical Physics, University of Wisconsin-Madison, Wisconsin; Department of Radiology, University of Wisconsin-Madison, Wisconsin; and Departments of Pediatrics and Biomedical Engineering; University of Wisconsin-Madison, Wisconsin
| | - Sean B Fain
- Department of Medical Physics, University of Wisconsin-Madison, Wisconsin; Department of Radiology, University of Wisconsin-Madison, Wisconsin; and Departments of Pediatrics and Biomedical Engineering; University of Wisconsin-Madison, Wisconsin
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A method for mapping regional oxygen and CO2 transfer in the lung. Respir Physiol Neurobiol 2015; 222:29-47. [PMID: 26563454 DOI: 10.1016/j.resp.2015.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 10/02/2015] [Accepted: 10/25/2015] [Indexed: 11/22/2022]
Abstract
This paper presents a novel approach to visualizing regional lung function, through quantitative three-dimensional maps of O2 and CO2 transfer rates. These maps describe the contribution of anatomical regions to overall gas exchange and demonstrate how transfer rates of the two gas species' differ regionally. An algorithm for generating such maps is presented, and for illustration, regional gas transfer maps were generated using values of ventilation and perfusion imaged by PET/CT for a healthy subject and an asthmatic patient after bronchoprovocation. In a sensitivity analysis, compartment values of gas transfer showed minor sensitivity to imaging noise in the ventilation and perfusion data, and moderate sensitivity to estimation errors in global lung input values, chiefly global alveolar ventilation, followed by cardiac output and arterial-venous O2 content difference. Gas transfer maps offer an intuitive display of physiologically relevant lung function at a regional level, the potential for an improved understanding of pulmonary gas exchange in health and disease, and potentially a presurgical evaluation tool.
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Ruppert K, Altes TA, Mata JF, Ruset IC, Hersman FW, Mugler JP. Detecting pulmonary capillary blood pulsations using hyperpolarized xenon-129 chemical shift saturation recovery (CSSR) MR spectroscopy. Magn Reson Med 2015; 75:1771-80. [PMID: 26017009 DOI: 10.1002/mrm.25794] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/06/2015] [Accepted: 05/05/2015] [Indexed: 01/11/2023]
Abstract
PURPOSE To investigate whether chemical shift saturation recovery (CSSR) MR spectroscopy with hyperpolarized xenon-129 is sensitive to the pulsatile nature of pulmonary blood flow during the cardiac cycle. METHODS A CSSR pulse sequence typically uses radiofrequency (RF) pulses to saturate the magnetization of xenon-129 dissolved in lung tissue followed, after a variable delay time, by an RF excitation and subsequent acquisition of a free-induction decay. Thereby it is possible to monitor the uptake of xenon-129 by lung tissue and extract physiological parameters of pulmonary gas exchange. In the current studies, the delay time was instead held at a constant value, which permitted observation of xenon-129 gas uptake as a function of breath-hold time. CSSR studies were performed in 13 subjects (10 healthy, 2 chronic obstructive pulmonary disease [COPD], 1 second-hand smoke exposure), holding their breath at total lung capacity. RESULTS The areas of the tissue/plasma and the red-blood-cell peaks in healthy subjects varied by an average of 1.7±0.7% and 15.1±3.8%, respectively, during the cardiac cycle. In 2 subjects with COPD these peak pulsations were not detectable during at least part of the measurement period. CONCLUSION CSSR spectroscopy is sufficiently sensitive to detect oscillations in the xenon-129 gas-uptake rate associated with the cardiac cycle.
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Affiliation(s)
- Kai Ruppert
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia, USA.,Department of Pulmonary Medicine, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Talissa A Altes
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Jaime F Mata
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Iulian C Ruset
- Xemed, LLC, Durham, New Hampshire, USA.,Department of Physics, University of New Hampshire, Durham, New Hampshire, USA
| | - F William Hersman
- Xemed, LLC, Durham, New Hampshire, USA.,Department of Physics, University of New Hampshire, Durham, New Hampshire, USA
| | - John P Mugler
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
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Monitoring Lung Volumes During Mechanical Ventilation. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193716 DOI: 10.1007/978-3-642-01219-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Respiratory inductive plethysmography (RIP) is a non-invasive method of measuring change in lung volume which is well-established as a monitor of tidal ventilation and thus respiratory patterns in sleep medicine. As RIP is leak independent, can measure end-expiratory lung volume as well as tidal volume and is applicable to both the ventilated and spontaneously breathing patient, there has been a recent interest in its use as a bedside tool in the intensive care unit.
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Ruppert K. Biomedical imaging with hyperpolarized noble gases. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:116701. [PMID: 25360484 DOI: 10.1088/0034-4885/77/11/116701] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Hyperpolarized noble gases (HNGs), polarized to approximately 50% or higher, have led to major advances in magnetic resonance (MR) imaging of porous structures and air-filled cavities in human subjects, particularly the lung. By boosting the available signal to a level about 100 000 times higher than that at thermal equilibrium, air spaces that would otherwise appear as signal voids in an MR image can be revealed for structural and functional assessments. This review discusses how HNG MR imaging differs from conventional proton MR imaging, how MR pulse sequence design is affected and how the properties of gas imaging can be exploited to obtain hitherto inaccessible information in humans and animals. Current and possible future imaging techniques, and their application in the assessment of normal lung function as well as certain lung diseases, are described.
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Güldner M, Becker S, Wolf U, Düber C, Friesenecker A, Gast KK, Heil W, Hoffmann C, Karpuk S, Otten EW, Rivoire J, Salhi Z, Scholz A, Schreiber LM, Terekhov M. Application unit for the administration of contrast gases for pulmonary magnetic resonance imaging: optimization of ventilation distribution for (3) He-MRI. Magn Reson Med 2014; 74:884-93. [PMID: 25213218 DOI: 10.1002/mrm.25433] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 11/05/2022]
Abstract
PURPOSE MRI of lung airspaces using gases with MR-active nuclei ((3) He, (129) Xe, and (19) F) is an important area of research in pulmonary imaging. The volume-controlled administration of gas mixtures is important for obtaining quantitative information from MR images. State-of-the-art gas administration using plastic bags (PBs) does not allow for a precise determination of both the volume and timing of a (3) He bolus. METHODS A novel application unit (AU) was built according to the requirements of the German medical devices law. Integrated spirometers enable the monitoring of the inhaled gas flow. The device is particularly suited for hyperpolarized (HP) gases (e.g., storage and administration with minimal HP losses). The setup was tested in a clinical trial (n = 10 healthy volunteers) according to the German medicinal products law using static and dynamic ventilation HP-(3) He MRI. RESULTS The required specifications for the AU were successfully realized. Compared to PB-administration, better reproducibility of gas intrapulmonary distribution was observed when using the AU for both static and dynamic ventilation imaging. CONCLUSION The new AU meets the special requirements for HP gases, which are storage and administration with minimal losses. Our data suggest that gas AU-administration is superior to manual modes for determining the key parameters of dynamic ventilation measurements.
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Affiliation(s)
- M Güldner
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - U Wolf
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - C Düber
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | | | - K K Gast
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - W Heil
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - C Hoffmann
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - S Karpuk
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - E W Otten
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - J Rivoire
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
| | - Z Salhi
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - A Scholz
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
| | - L M Schreiber
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
| | - M Terekhov
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
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Liu Z, Araki T, Okajima Y, Albert M, Hatabu H. Pulmonary hyperpolarized noble gas MRI: Recent advances and perspectives in clinical application. Eur J Radiol 2014; 83:1282-1291. [DOI: 10.1016/j.ejrad.2014.04.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/21/2014] [Accepted: 04/19/2014] [Indexed: 12/01/2022]
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Hamedani H, Kadlecek SJ, Ishii M, Emami K, Kuzma NN, Xin Y, Rossman M, Rizi RR. A variability study of regional alveolar oxygen tension measurement in humans using hyperpolarized (3) He MRI. Magn Reson Med 2013; 70:1557-66. [PMID: 23382040 DOI: 10.1002/mrm.24604] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/28/2012] [Accepted: 11/27/2012] [Indexed: 11/06/2022]
Abstract
PURPOSE A systematic study of the short-term and long-term variability of regional alveolar partial pressure of oxygen tension (pA O2 ) measurements using (3) He magnetic resonance imaging was presented. Additionally, the repeatability of the average evaluated pA O2 was compared with that of the standard pulmonary function tests. METHODS Pulmonary function test and pA O2 imaging were performed on 4 nonsmokers (1 M, 3 F, 56 ± 1.7 years) and 4 smokers (3 M, 1 F, 52 ± 7.5 years) during three visits over the course of 2 weeks. Two measurements were performed per visit. Variability of pA O2 was assessed using a mixed-effect model, with an intraclass correlation coefficient calculated for each group. The coefficient of variation of pA O2 over the 3-day period was also compared with the coefficient of variation of pulmonary function test results. RESULTS Short-term regional variability based on intraclass correlation coefficient was 0.71 for nonsmokers, and 0.63 for smokers, with long-term variability significantly lower at 0.59 and 0.47, respectively. While the coefficient of variation of the average pA O2 was similar to the repeatability of the diffusing capacity of CO, it was significantly higher than that of Forced Vital Capacity (P = 0.02). CONCLUSION Short-term and long-term pA O2 variability differences were used as an indication of true physiological changes in order to measure technical reproducibility. Smokers show higher physiologic variability and less technical reproducibility. The suggested pA O2 -imaging technique showed a reasonable regional repeatability in nonsmokers as well as the ability to detect differences between the two groups with similar reproducibility and superior discriminatory ability when compared with pulmonary function tests.
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Affiliation(s)
- Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Acosta RH, Blümler P, Münnemann K, Spiess HW. Mixture and dissolution of laser polarized noble gases: spectroscopic and imaging applications. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 66:40-69. [PMID: 22980033 DOI: 10.1016/j.pnmrs.2012.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/20/2012] [Indexed: 06/01/2023]
Affiliation(s)
- Rodolfo H Acosta
- FAMAF, Universidad Nacional de Córdoba, IFEG - CONICET, Córdoba, Argentina
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Abstract
Several methods allow regional gas exchange to be inferred from imaging of regional ventilation and perfusion (V/Q) ratios. Each method measures slightly different aspects of gas exchange and has inherent advantages and drawbacks that are reviewed. Single photon emission computed tomography can provide regional measure of ventilation and perfusion from which regional V/Q ratios can be derived. PET methods using inhaled or intravenously administered nitrogen-13 provide imaging of both regional blood flow, shunt, and ventilation. Electric impedance tomography has recently been refined to allow simultaneous measurements of both regional ventilation and blood flow. MRI methods utilizing hyperpolarized helium-3 or xenon-129 are currently being refined and have been used to estimate local PaO(2) in both humans and animals. Microsphere methods are included in this review as they provide measurements of regional ventilation and perfusion in animals. One of their advantages is their greater spatial resolution than most imaging methods and the ability to use them as gold standards against which new imaging methods can be tested. In general, the reviewed methods differ in characteristics such as spatial resolution, possibility of repeated measurements, radiation exposure, availability, expensiveness, and their current stage of development.
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Affiliation(s)
- Johan Petersson
- Department of Anesthesiology and Intensive Care, Karolinska University Hospital Solna, Stockholm, Sweden.
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Kadlecek S, Mongkolwisetwara P, Xin Y, Ishii M, Profka H, Emami K, Rizi R. Regional determination of oxygen uptake in rodent lungs using hyperpolarized gas and an analytical treatment of intrapulmonary gas redistribution. NMR IN BIOMEDICINE 2011; 24:1253-1263. [PMID: 21387449 DOI: 10.1002/nbm.1685] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 12/09/2010] [Accepted: 01/10/2011] [Indexed: 05/30/2023]
Abstract
A method is presented which allows for the accurate extraction of regional functional metrics in rodent lungs using hyperpolarized gas. The technique is based on the combination of measured T(1) decay, an independent measure of specific ventilation and mass balance considerations to extract the regional oxygen levels and uptake. In phantom and animal experiments, it is demonstrated that the redistribution of gas during the measurement is a significant confounding factor, and this effect is addressed analytically. The resulting parameterization of gas flow increases the accuracy of oxygen-sensitive MRI, and may also be used independently to assess air trapping and airway constriction. Limitations of the technique with respect to spatial resolution and robustness are also discussed.
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Affiliation(s)
- Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Salhi Z, Großmann T, Gueldner M, Heil W, Karpuk S, Otten EW, Rudersdorf D, Surkau R, Wolf U. Recycling of 3He from lung magnetic resonance imaging. Magn Reson Med 2011; 67:1758-63. [DOI: 10.1002/mrm.23154] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 07/03/2011] [Accepted: 07/25/2011] [Indexed: 11/10/2022]
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Eichinger M, Heussel CP, Kauczor HU, Tiddens H, Puderbach M. Computed tomography and magnetic resonance imaging in cystic fibrosis lung disease. J Magn Reson Imaging 2011; 32:1370-8. [PMID: 21105141 DOI: 10.1002/jmri.22374] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Computed tomography (CT) is the current "gold standard" for assessment of lung morphology and is so far the most reliable imaging modality for monitoring cystic fibrosis (CF) lung disease. CT has a much higher radiation exposure than chest x-ray. The cumulative radiation dose for life-long repeated CT scans has limited its use for CF patients as their life expectancy increases. Clearly, no dose would be preferable over low dose when the same or more relevant information can be obtained. Magnetic resonance imaging (MRI) is comparable to CT with regard to the detection of most morphological changes in the CF lung. It is thought to be less sensitive to detect small airway disease. At the same time, MRI is superior to CT when it comes to the assessment of functional changes such as altered pulmonary perfusion. The recommendation is to further reduce radiation dose related to the use of CT and to use MRI in the follow-up of morphological changes where possible.
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Affiliation(s)
- Monika Eichinger
- German Cancer Research Center (DKFZ) Heidelberg, Radiology (E010), Heidelberg, Germany
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Zurek M, Crémillieux Y. MRI of the lung: non-invasive protocols and applications to small animal models of lung disease. Methods Mol Biol 2011; 771:459-474. [PMID: 21874493 DOI: 10.1007/978-1-61779-219-9_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Magnetic resonance imaging (MRI) can be used in pre-clinical studies as a non-invasive imaging tool for assessing the morphological and functional impact of lung diseases and for evaluating the efficacy of potential treatments for airways diseases. Hyperpolarized gases ((3)He or (129)Xe) MRI provides insight into the lung ventilation function. Lung proton MRI provides information on lung diseases associated with inflammatory activity or with changes in lung tissue density. These imaging techniques can be implemented with non-invasive protocols appropriate for longitudinal investigations in small animal models of lung diseases. This chapter will detail two (3)He and proton lung MR imaging protocols applied on two models of lung pathology in rodents.
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The role of advanced imaging techniques in cystic fibrosis follow-up: is there a place for MRI? Pediatr Radiol 2010; 40:844-9. [PMID: 20432002 DOI: 10.1007/s00247-010-1589-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 01/24/2010] [Indexed: 12/24/2022]
Abstract
Cystic fibrosis (CF) lung disease is caused by mutations in the CFTR-gene and remains one of the most frequent lethal inherited diseases in the Caucasian population. Given the progress in CF therapy and the consecutive improvement in prognosis, monitoring of disease progression and effectiveness of therapeutic interventions with repeated imaging of the CF lung plays an increasingly important role. So far, the chest radiograph has been the most widely used imaging modality to monitor morphological changes in the CF lung. CT is the gold standard for assessment of morphological changes of airways and lung parenchyma. Considering the necessity of life-long repeated imaging studies, the cumulative radiation doses reached with CT is problematic for CF patients. A sensitive, non-invasive and quantitative technique without radiation exposure is warranted for monitoring of disease activity. In previous studies, MRI proved to be comparable to CT regarding the detection of morphological changes in the CF lung without using ionising radiation. Furthermore, MRI was shown to be superior to CT regarding assessment of functional changes of the lung. This review presents the typical morphological and functional MR imaging findings with respect to MR-based follow-up of CF lung disease. MRI offers a variety of techniques for morphological and functional imaging of the CF lung. Using this radiation free technique short- and long-term follow-up studies are possible enabling an individualised guidance of the therapy.
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Scholz AWK, Eberle B, Heussel CP, David M, Schmittner MD, Quintel M, Schreiber LM, Weiler N. Ventilation-Perfusion Ratio in Perflubron During Partial Liquid Ventilation. Anesth Analg 2010; 110:1661-8. [DOI: 10.1213/ane.0b013e3181d3e1d5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Meise FM, Rivoire J, Terekhov M, Wiggins GC, Keil B, Karpuk S, Salhi Z, Wald LL, Schreiber LM. Design and evaluation of a 32-channel phased-array coil for lung imaging with hyperpolarized 3-helium. Magn Reson Med 2010; 63:456-64. [PMID: 20099333 DOI: 10.1002/mrm.22265] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Imaging with hyperpolarized 3-helium is becoming an increasingly important technique for MRI diagnostics of the lung but is hampered by long breath holds (>20 sec), which are not always applicable in patients with severe lung disease like chronic obstructive pulmonary disease (COPD) or alpha-1-anti-trypsin deficiency. Additionally, oxygen-induced depolarization decay during the long breath holds complicates interpretation of functional data such as apparent diffusion coefficients. To address these issues, we describe and validate a 1.5-T, 32-channel array coil for accelerated (3)He lung imaging and demonstrate its ability to speed up imaging (3)He. A signal-to-noise ratio increase of up to a factor of 17 was observed compared to a conventional double-resonant birdcage for unaccelerated imaging, potentially allowing increased image resolution or decreased gas production requirements. Accelerated imaging of the whole lung with one-dimensional and two-dimensional acceleration factors of 4 and 4 x 2, respectively, was achieved while still retaining excellent image quality. Finally, the potential of highly parallel detection in lung imaging is demonstrated with high-resolution morphologic and functional images.
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Affiliation(s)
- Florian M Meise
- Section of Medical Physics, Department of Diagnostic and Interventional Radiology, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany
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Hellinger JC, Medina LS, Epelman M. Pediatric Advanced Imaging and Informatics: State of the Art. Semin Ultrasound CT MR 2010; 31:171-93. [DOI: 10.1053/j.sult.2010.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Hyperpolarized gas magnetic resonance imaging has been explored extensively as a promising tool for the quantitative evaluation of regional pulmonary pathophysiology. This noninvasive technique is capable of providing both structural information down to the level of the alveolar microstructure and functional information, such as dynamic ventilation, intrapulmonary partial pressure of oxygen, and alveolar surface area. This study reviews the role of hyperpolarized 3-helium and 129-xenon magnetic resonance imaging in this research.
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Miller GW, Mugler JP, Altes TA, Cai J, Mata JF, de Lange EE, Tobias WA, Cates GD, Brookeman JR. A short-breath-hold technique for lung pO2 mapping with 3He MRI. Magn Reson Med 2010; 63:127-36. [PMID: 19918891 PMCID: PMC3320736 DOI: 10.1002/mrm.22181] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 07/29/2009] [Indexed: 11/06/2022]
Abstract
A pulse-sequence strategy was developed for generating regional maps of alveolar oxygen partial pressure (pO2) in a single 6-sec breath hold, for use in human subjects with impaired lung function. Like previously described methods, pO2 values are obtained by measuring the oxygen-induced T1 relaxation of inhaled hyperpolarized 3He. Unlike other methods, only two 3He images are acquired: one with reverse-centric and the other with centric phase-encoding order. This phase-encoding arrangement minimizes the effects of regional flip-angle variations, so that an accurate map of instantaneous pO2 can be calculated from two images acquired a few seconds apart. By combining this phase-encoding strategy with variable flip angles, the vast majority of the hyperpolarized magnetization goes directly into the T1 measurement, minimizing noise in the resulting pO2 map. The short-breath-hold pulse sequence was tested in phantoms containing known O2 concentrations. The mean difference between measured and prepared pO2 values was 1 mm Hg. The method was also tested in four healthy volunteers and three lung-transplant patients. Maps of healthy subjects were largely uniform, whereas focal regions of abnormal pO2 were observed in diseased subjects. Mean pO2 values varied with inhaled O2 concentration. Mean pO2 was consistent with normal steady-state values in subjects who inhaled 3He diluted only with room air.
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Affiliation(s)
- G Wilson Miller
- Center for In-Vivo Hyperpolarized Gas MR Imaging, Department of Radiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
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Rudolph A, Markstaller K, Gast KK, David M, Schreiber WG, Eberle B. Visualization of alveolar recruitment in a porcine model of unilateral lung lavage using 3He-MRI. Acta Anaesthesiol Scand 2009; 53:1310-6. [PMID: 19681783 DOI: 10.1111/j.1399-6576.2009.02069.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND In the acute respiratory distress syndrome potentially recruitable lung volume is currently discussed. (3)He-magnetic resonance imaging ((3)He-MRI) offers the possibility to visualize alveolar recruitment directly. METHODS With the approval of the state animal care committee, unilateral lung damage was induced in seven anesthetized pigs by saline lavage of the right lungs. The left lung served as an intraindividual control (healthy lung). Unilateral lung damage was confirmed by conventional proton MRI and spiral-CT scanning. The total aerated lung volume was determined both at a positive end-expiratory pressure (PEEP) of 0 and 10 mbar from three-dimensionally reconstructed (3)He images, both for healthy and damaged lungs. The fractional increase of aerated volume in damaged and healthy lungs, followed by a PEEP increase from 0 to 10 mbar, was compared. RESULTS Aerated gas space was visualized with a high spatial resolution in the three-dimensionally reconstructed (3)He-MR images, and aeration defects in the lavaged lung matched the regional distribution of atelectasis in proton MRI. After recruitment and PEEP increase, the aerated volume increased significantly both in healthy lungs from 415 ml [270-445] (median [min-max]) to 481 ml [347-523] and in lavaged lungs from 264 ml [71-424] to 424 ml [129-520]. The fractional increase in lavaged lungs was significantly larger than that in healthy lungs (healthy: 17% [11-38] vs. lavage: 42% [14-90] (P=0.031). CONCLUSION The (3)He-MRI signal might offer an experimental approach to discriminate atelectatic vs. poor aerated lung areas in a lung damage animal model. Our results confirm the presence of potential recruitable lung volume by either alveolar collapse or alveolar flooding, in accordance with previous reports by computed tomography.
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Affiliation(s)
- A Rudolph
- Department of Anaesthesiology, Johannes Gutenburg-University, Langenbeckstrasse 1, Mainz, Germany.
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27
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Driehuys B, Möller HE, Cleveland ZI, Pollaro J, Hedlund LW. Pulmonary perfusion and xenon gas exchange in rats: MR imaging with intravenous injection of hyperpolarized 129Xe. Radiology 2009; 252:386-93. [PMID: 19703880 PMCID: PMC2753782 DOI: 10.1148/radiol.2513081550] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
PURPOSE To develop and demonstrate a method for regional evaluation of pulmonary perfusion and gas exchange based on intravenous injection of hyperpolarized xenon 129 ((129)Xe) and subsequent magnetic resonance (MR) imaging of the gas-phase (129)Xe emerging in the alveolar airspaces. MATERIALS AND METHODS Five Fischer 344 rats that weighed 200-425 g were prepared for imaging according to an institutional animal care and use committee-approved protocol. Rats were ventilated, and a 3-F catheter was placed in the jugular (n = 1) or a 24-gauge catheter in the tail (n = 4) vein. Imaging and spectroscopy of gas-phase (129)Xe were performed after injecting 5 mL of half-normal saline saturated with (129)Xe hyperpolarized to 12%. Corresponding ventilation images were obtained during conventional inhalation delivery of hyperpolarized (129)Xe. RESULTS Injections of (129)Xe-saturated saline were well tolerated and produced a strong gas-phase (129)Xe signal in the airspaces that resulted from (129)Xe transport through the pulmonary circulation and diffusion across the blood-gas barrier. After a single injection, the emerging (129)Xe gas could be detected separately from (129)Xe remaining in the blood and was imaged with an in-plane resolution of 1 x 1 mm and a signal-to-noise ratio of 25. Images in one rat revealed a matched ventilation-perfusion deficit, while images in another rat showed that xenon gas exchange was temporarily impaired after saline overload, with recovery of function 1 hour later. CONCLUSION MR imaging of gas-phase (129)Xe emerging in the pulmonary airspaces after intravenous injection has the potential to become a sensitive and minimally invasive new tool for regional evaluation of pulmonary perfusion and gas exchange. SUPPLEMENTAL MATERIAL http://radiology.rsnajnls.org/cgi/content/full/2513081550/DC1.
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Affiliation(s)
- Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, NC 27710, USA.
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Yu J, Law M, Kadlecek S, Emami K, Ishii M, Stephen M, Woodburn JM, Vahdat V, Rizi RR. Simultaneous measurement of pulmonary partial pressure of oxygen and apparent diffusion coefficient by hyperpolarized 3He MRI. Magn Reson Med 2009; 61:1015-21. [PMID: 19230017 DOI: 10.1002/mrm.21854] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hyperpolarized (3)He (HP (3)He) MRI shows promise to assess structural and functional pulmonary parameters in a sensitive, regional, and noninvasive way. Structural HP (3)He MRI has applied the apparent diffusion coefficient (ADC) for the detection of disease-induced lung microstructure changes at the alveolar level, and HP (3)He pulmonary partial pressure of oxygen (pO(2)) imaging measures the oxygen transfer efficiency between the lung and blood stream. Although both parameters are affected in chronic obstructive pulmonary disease (COPD), a quantitative assessment of the regional correlation of the two parameters has not been reported in the literature. In this work, a single acquisition technique for the simultaneous measurement of ADC and pO(2) is presented. This technique is based on the multiple regression method, in which a general linear estimator is used to retrieve the values of ADC and pO(2) from a series of measurements. The measurement uncertainties are also analytically derived and used to find an optimal measurement scheme. The technique was first tested on a phantom model, and then on an in vivo normal pig experiment. A case study was performed on a COPD patient, which showed that in a region of interest ADC was 29% higher while oxygen depletion rate was 61% lower than the corresponding global average values.
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Affiliation(s)
- Jiangsheng Yu
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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29
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Abstract
Chronic obstructive pulmonary disease (COPD) is divided into pulmonary emphysema and chronic bronchitis (CB). Emphysema is defined patho-anatomically as "permanent enlargement of airspaces distal to the terminal bronchiole, accompanied by the destruction of their walls, and without obvious fibrosis" (1). These lesions are readily identified and quantitated using computed tomography (CT), whereas the accompanying hyperinflation is best detected on plain chest X-ray, especially in advanced disease. The diagnosis of CB is clinical and relies on the presence of productive cough for 3 months in 2 or more successive years. The pathological changes of mucosal inflammation and bronchial wall thickening have been more difficult to identify with available imaging techniques. However, recent studies using Multi-detector row CT (MDCT) reported more reproducible assessment of air wall thickening.
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Affiliation(s)
- Saher B Shaker
- Department of Respiratory Medicine, Gentofte University Hospital, Hellerup, Denmark.
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Rodríguez I, Pérez-Rial S, González-Jimenez J, Pérez-Sánchez J, Herranz F, Beckmann N, Ruíz-Cabello J. Magnetic resonance methods and applications in pharmaceutical research. J Pharm Sci 2008; 97:3637-65. [PMID: 18228597 DOI: 10.1002/jps.21281] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This review presents an overview of some recent magnetic resonance (MR) techniques for pharmaceutical research. MR is noninvasive, and does not expose subjects to ionizing radiation. Some methods that have been used in pharmaceutical research MR include magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) methods, among them, diffusion-weighted MRI, perfusion-weighted MRI, functional MRI, molecular imaging and contrast-enhance MRI. Some applications of MR in pharmaceutical research include MR in metabonomics, in vivo MRS, studies in cerebral ischemia and infarction, degenerative joint diseases, oncology, cardiovascular disorders, respiratory diseases and skin diseases. Some of these techniques, such as cardiac and joint imaging, or brain fMRI are standard, and are providing relevant data routinely. Skin MR and hyperpolarized gas lung MRI are still experimental. In conclusion, considering the importance of finding and characterizing biomarkers for improved drug evaluation, it can be expected that the use of MR techniques in pharmaceutical research is going to increase in the near future.
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Affiliation(s)
- I Rodríguez
- Grupo de Resonancia Magnética, Instituto de Estudios Biofuncionales, Universidad Complutense de Madrid, Paseo Juan XXIII 1, Madrid 28040, Spain
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Mosbah K, Ruiz-Cabello J, Berthezène Y, Crémillieux Y. Aerosols and gaseous contrast agents for magnetic resonance imaging of the lung. CONTRAST MEDIA & MOLECULAR IMAGING 2008; 3:173-90. [DOI: 10.1002/cmmi.252] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Yu J, Rajaei S, Ishii M, Law M, Emami K, Woodburn JM, Kadlecek S, Vahdat V, Rizi RR. Measurement of pulmonary partial pressure of oxygen and oxygen depletion rate with hyperpolarized helium-3 MRI: a preliminary reproducibility study on pig model. Acad Radiol 2008; 15:702-12. [PMID: 18486007 DOI: 10.1016/j.acra.2008.01.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2007] [Revised: 01/18/2008] [Accepted: 01/19/2008] [Indexed: 10/22/2022]
Abstract
RATIONAL AND OBJECTIVES Pulmonary partial pressure of oxygen (pO(2)) and oxygen depletion rate (R) are two important parameters of lung function. The dependence of hyperpolarized (3)He (HP (3)He) T(1) on local oxygen concentration provides the basis for high-resolution mapping of the regional distributions of pO(2) and R in the lung. Although the oxygen-sensitive HP (3)He magnetic resonance imaging technique has been applied in human subjects and several animal species, reproducibility studies are rarely reported in the literature. This work presents a preliminary reproducibility study on a pig model. In this study, important scan parameters, such as measurement timing and flip angle, are optimized to minimize the noise-induced measurement uncertainty. MATERIALS AND METHODS In the in vivo study, five normal pigs and one diseased pig with simulated pulmonary emboli were scanned with a small flip angle gradient echo sequence. The pulmonary oxygen measurement was repeated two to four times in each pig. In each measurement, a series of six images were acquired with optimal timing and flip angle. The parametric maps were generated using a bin-based data processing procedure that applied the multiple regression fitting method to extract the pO(2) and R. Variations of global mean, percentiles, and regions of interest were calculated from the maps to analyze reproducibility. RESULTS The global statistical analyses show that average variation of global mean is 10.7% for pO(2) and 23.8% for R, and that the average variation of percentiles (10th, 25th, 50th, 75th, and 90th) and interquartile range is 14.8% for pO(2) and 30.4% for R. The region-of-interest analysis on the manually selected regions shows that the average variation of mean is 12.6% for pO(2) and 21.9% for R. CONCLUSION In this work, a preliminary study on the reproducibility of measuring pO(2) and R with HP (3)He magnetic resonance imaging on a pig model is presented.
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Yu J, Ishii M, Law M, Woodburn JM, Emami K, Kadlecek S, Vahdat V, Guyer RA, Rizi RR. Optimization of scan parameters in pulmonary partial pressure oxygen measurement by hyperpolarized 3He MRI. Magn Reson Med 2008; 59:124-31. [PMID: 18050348 DOI: 10.1002/mrm.21416] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The dependence of hyperpolarized (HP) (3)He T(1) on local oxygen concentration provides the basis for measuring the partial pressure of oxygen (pO(2)) and oxygen depletion rate (R) in the lungs. Precise measurements of this type are difficult because the oxygen effect manifests itself through a decay of signal, leading to noisy images at the end of the series. The depolarization caused by RF excitation pulses further complicates the problem. It is therefore important to optimize scan parameters, such as measurement timing and flip angle, to obtain accurate and reproducible measurements. This work presents a new single-acquisition technique in conjunction with the multiple regression fitting method for data evaluation. Analytical expressions for the measurement uncertainties are derived. A total of four types of single-acquisition timing schemes are investigated; simulation shows a large uncertainty variation between these schemes (pO(2): 7.5-30.2%; R: 47.4-173.7%). A basic procedure for optimizing scan parameters is then described. A phantom experiment was conducted to verify the simulation results. Repeated in vivo measurements with the optimal scheme in a rabbit experiment showed that average variation of global mean is 6.2% for pO(2) and 12.0% for R, and that the average variation of percentiles (10th, 25th, 50th, 75th, and 90th) is 8.7% for pO(2) and 19.0% for R.
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Affiliation(s)
- Jiangsheng Yu
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Abstract
Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled multi-detector row CT allow for quantification of presence and distribution of parenchymal and airway pathology; xenon gas can be employed to assess regional ventilation of the lungs, and rapid bolus injections of iodinated contrast agent can provide a quantitative measure of regional parenchymal perfusion. Advances in MRI of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized gas imaging, which allow functional assessment, including ventilation/perfusion, microscopic air space measurements, and gas flow and transport dynamics.
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Affiliation(s)
- Edwin J R van Beek
- Department of Radiology, Carver College of Medicine, University of Iowa, C-751 GH, 200 Hawkins Drive, Iowa City, IA 52242-1077, USA.
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Oxygen-sensitive 3He-MRI in bronchiolitis obliterans after lung transplantation. Eur Radiol 2007; 18:530-7. [PMID: 17926041 PMCID: PMC2755794 DOI: 10.1007/s00330-007-0778-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 07/31/2007] [Accepted: 08/27/2007] [Indexed: 10/27/2022]
Abstract
Oxygen-sensitive 3He-MRI was studied for the detection of differences in intrapulmonary oxygen partial pressure (pO2) between patients with normal lung transplants and those with bronchiolitis obliterans syndrome (BOS). Using software developed in-house, oxygen-sensitive 3He-MRI datasets from patients with normal lung grafts (n = 8) and with BOS (n = 6) were evaluated quantitatively. Datasets were acqiured on a 1.5-T system using a spoiled gradient echo pulse sequence. Underlying diseases were pulmonary emphysema (n = 10 datasets) and fibrosis (n = 4). BOS status was verified by pulmonary function tests. Additionally, 3He-MRI was assessed blindedly for ventilation defects. Median intrapulmonary pO2 in patients with normal lung grafts was 146 mbar compared with 108 mbar in patients with BOS. Homogeneity of pO2 distribution was greater in normal grafts (standard deviation pO2 34 versus 43 mbar). Median oxygen decrease rate during breath hold was higher in unaffected patients (-1.75 mbar/s versus -0.38 mbar/s). Normal grafts showed fewer ventilation defects (5% versus 28%, medians). Oxygen-sensitive 3He-MRI appears capable of demonstrating differences of intrapulmonary pO2 between normal lung grafts and grafts affected by BOS. Oxygen-sensitive 3He-MRI may add helpful regional information to other diagnostic techniques for the assessment and follow-up of lung transplant recipients.
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Patz S, Hersman FW, Muradian I, Hrovat MI, Ruset IC, Ketel S, Jacobson F, Topulos GP, Hatabu H, Butler JP. Hyperpolarized (129)Xe MRI: a viable functional lung imaging modality? Eur J Radiol 2007; 64:335-44. [PMID: 17890035 PMCID: PMC2271064 DOI: 10.1016/j.ejrad.2007.08.008] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Revised: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 11/21/2022]
Abstract
The majority of researchers investigating hyperpolarized gas MRI as a candidate functional lung imaging modality have used (3)He as their imaging agent of choice rather than (129)Xe. This preference has been predominantly due to, (3)He providing stronger signals due to higher levels of polarization and higher gyromagnetic ratio, as well as its being easily available to more researchers due to availability of polarizers (USA) or ease of gas transport (Europe). Most researchers agree, however, that hyperpolarized (129)Xe will ultimately emerge as the imaging agent of choice due to its unlimited supply in nature and its falling cost. Our recent polarizer technology delivers vast improvements in hyperpolarized (129)Xe output. Using this polarizer, we have demonstrated the unique property of xenon to measure alveolar surface area noninvasively. In this article, we describe our human protocols and their safety, and our results for the measurement of the partial pressure of pulmonary oxygen (pO(2)) by observation of (129)Xe signal decay. We note that the measurement of pO(2) by observation of (129)Xe signal decay is more complex than that for (3)He because of an additional signal loss mechanism due to interphase diffusion of (129)Xe from alveolar gas spaces to septal tissue. This results in measurements of an equivalent pO(2) that accounts for both traditional T(1) decay from pO(2) and that from interphase diffusion. We also provide an update on new technological advancements that form the foundation for an improved compact design polarizer as well as improvements that provide another order-of-magnitude scale-up in xenon polarizer output.
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Affiliation(s)
- Samuel Patz
- Center for Pulmonary Functional Imaging, Brigham and Women's Hospital, 221 Longwood Avenue, Boston, MA 02115, USA.
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Cieślar K, Alsaid H, Stupar V, Gaillard S, Canet-Soulas E, Fissoune R, Crémillieux Y. Measurement of nonlinear pO2 decay in mouse lungs using 3He-MRI. NMR IN BIOMEDICINE 2007; 20:383-91. [PMID: 17451167 DOI: 10.1002/nbm.1124] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Spatial and temporal variations in oxygen partial pressure (pO(2)) during breath-hold can be exploited to obtain important regional parameters of lung function. In the course of apnea, the oxygen concentration is known to decay exponentially. Therefore, the initial pO(2) (p(0)) can be used to represent local ventilation, and the oxygen depletion time constant can characterize perfusion. The protocol, based on a nonlinear model of pO(2) decay, was validated in six healthy mice. Parametric maps of p(0) and oxygen depletion time constant were obtained for pure (3)He and (3)He/air mixture. The mean measured values of p(0) were 77 +/- 9 mbar for the pure (3)He insufflation and 107 +/- 5 mbar for (3)He/air mixture, in agreement with the predefined p(0) values: 75 +/- 15 mbar and 123 +/- 15 mbar, respectively. The mean measured oxygen depletion time constants were 6.5 +/- 0.2 s for pure (3)He and 7.1 +/- 0.8 s for the (3)He/air mixture, in agreement with physiology.
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Cieślar K, Stupar V, Canet-Soulas E, Gaillard S, Crémillieux Y. Alveolar oxygen partial pressure and oxygen depletion rate mapping in rats using 3He ventilation imaging. Magn Reson Med 2007; 57:423-30. [PMID: 17152086 DOI: 10.1002/mrm.21110] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A hyperpolarized 3He ventilation imaging protocol was implemented to assess alveolar pO2 values and the oxygen depletion rate in rats. The imaging protocol, which is based on spiral k-space sampling, was designed to acquire a high signal-to-noise ratio (SNR) T1-weighted ventilation series of images in a single breath-hold. Simulations were performed to estimate the accuracy and dependence of the pO2 imaging protocol on the image SNR and the RF flip-angle determination. The imaging protocol was validated in vitro in phantoms and in vivo in rats. Imaging sessions were carried out for different inhaled O2 concentrations ranging from 20% to 40%. Parametric maps of alveolar pO2 and oxygen depletion rate were generated from the series of images. For each investigated animal, the differences in measured alveolar pO2 values are in agreement with the changes in inhaled O2 concentration. The oxygen depletion rates, ranging between 0.7 and 8.0 mbar s-1, are in close agreement with the published values for healthy rats.
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Hopkins SR, Levin DL, Emami K, Kadlecek S, Yu J, Ishii M, Rizi RR. Advances in magnetic resonance imaging of lung physiology. J Appl Physiol (1985) 2006; 102:1244-54. [PMID: 17158249 DOI: 10.1152/japplphysiol.00738.2006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review presents an overview of some recent magnetic resonance imaging (MRI) techniques for measuring aspects of local physiology in the lung. MRI is noninvasive, relatively high resolution, and does not expose subjects to ionizing radiation. Conventional MRI of the lung suffers from low signal intensity caused by the low proton density and the large degree of microscopic field inhomogeneity that degrades the magnetic resonance signal and interferes with image acquisition. However, in recent years, there have been rapid advances in both hardware and software design, allowing these difficulties to be minimized. This review focuses on some newer techniques that measure regional perfusion, ventilation, gas diffusion, ventilation-to-perfusion ratio, partial pressure of oxygen, and lung water. These techniques include contrast-enhanced and arterial spin-labeling techniques for measuring perfusion, hyperpolarized gas techniques for measuring regional ventilation, and apparent diffusion coefficient and multiecho and gradient echo techniques for measuring proton density and lung water. Some of the major advantages and disadvantages of each technique are discussed. In addition, some of the physiological issues associated with making measurements are discussed, along with strategies for understanding large and complex data sets.
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Affiliation(s)
- Susan R Hopkins
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA.
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40
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Hoffman EA, Simon BA, McLennan G. State of the Art. A structural and functional assessment of the lung via multidetector-row computed tomography: phenotyping chronic obstructive pulmonary disease. PROCEEDINGS OF THE AMERICAN THORACIC SOCIETY 2006; 3:519-32. [PMID: 16921136 PMCID: PMC2647643 DOI: 10.1513/pats.200603-086ms] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 05/30/2006] [Indexed: 11/20/2022]
Abstract
With advances in multidetector-row computed tomography (MDCT), it is now possible to image the lung in 10 s or less and accurately extract the lungs, lobes, and airway tree to the fifth- through seventh-generation bronchi and to regionally characterize lung density, texture, ventilation, and perfusion. These methods are now being used to phenotype the lung in health and disease and to gain insights into the etiology of pathologic processes. This article outlines the application of these methodologies with specific emphasis on chronic obstructive pulmonary disease. We demonstrate the use of our methods for assessing regional ventilation and perfusion and demonstrate early data that show, in a sheep model, a regionally intact hypoxic pulmonary vasoconstrictor (HPV) response with an apparent inhibition of HPV regionally in the presence of inflammation. We present the hypothesis that, in subjects with pulmonary emphysema, one major contributing factor leading to parenchymal destruction is the lack of a regional blunting of HPV when the regional hypoxia is related to regional inflammatory events (bronchiolitis or alveolar flooding). If maintaining adequate blood flow to inflamed lung regions is critical to the nondestructive resolution of inflammatory events, the pathologic condition whereby HPV is sustained in regions of inflammation would likely have its greatest effect in the lung apices where blood flow is already reduced in the upright body posture.
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Affiliation(s)
- Eric A Hoffman
- Department of Radiology, University of Iowa, 200 Hawkins Drive, CC701 GH, Iowa City, 52242, USA.
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41
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Abstract
With the emergence of multidetector-row computed tomography (CT) it is now possible to image both structure and function via use of a single imaging modality. Breath-hold spiral CT provides detail of the airway and vascular trees along with texture reflective of the state of the lung parenchyma. Use of stable xenon gas wash-in and/or wash-out methods using an axial mode of the CT scanner whereby images are acquired through gating to the respiratory cycle provide detailed images of regional ventilation with isotropic voxel dimensions now on the order of 0.4 mm. Axial scanning during a breath hold and gating to the electrocardiogram during the passage of a sharp bolus injection of iodinated contrast agent provide detailed images of regional pulmonary perfusion. These dynamic CT methods for the study of regional lung function are discussed in the context of other methods that have been used to study heterogeneity of lung function.
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Affiliation(s)
- Eric A Hoffman
- Department of Radiology, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52240, USA.
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Musch G, Venegas JG. Positron emission tomography imaging of regional pulmonary perfusion and ventilation. Ann Am Thorac Soc 2006; 2:522-7, 508-9. [PMID: 16352758 PMCID: PMC2713340 DOI: 10.1513/pats.200508-088ds] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Positron emission tomography (PET) imaging is a noninvasive, quantitative method to assess pulmonary perfusion and ventilation in vivo. The core of this article focuses on the use of [13N]nitrogen (13N2) and PET to assess regional gas exchange. Regional perfusion and shunt can be measured with the 13N2-saline bolus infusion technique. A bolus of 13N2, dissolved in saline solution, is injected intravenously at the start of a brief apnea, while the tracer kinetics in the lung is measured by a sequence of PET frames. Because of its low solubility in blood, virtually all 13N2 delivered to aerated lung regions diffuses into the alveolar airspace, where it accumulates in proportion to regional perfusion during the apnea. In contrast, lung regions that are perfused but are not aerated and do not exchange gas (i.e., "shunting" units) do not retain 13N2 during apnea and the tracer concentration drops after the initial peak. Accurate estimates of regional perfusion and regional shunt can be derived by applying a mathematical model to the pulmonary kinetics of a 13N2-saline bolus. When breathing is resumed, specific alveolar ventilation can be calculated from the tracer washout rate, because 13N2 is eliminated almost exclusively by ventilation. Because of the rapid elimination of the tracer, 13N2 infusion scans can be followed by 13N2 inhalation scans that allow determination of regional gas fraction. This article describes insights into the pathophysiology of acute lung injury, pulmonary embolism, and asthma that have been gained by PET imaging of regional gas exchange.
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Affiliation(s)
- Guido Musch
- Department of Anesthesia and Critical Care, CLN 309, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
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Schreiber WG, Morbach AE, Stavngaard T, Gast KK, Herweling A, Søgaard LV, Windirsch M, Schmiedeskamp J, Heussel CP, Kauczor HU. Assessment of lung microstructure with magnetic resonance imaging of hyperpolarized Helium-3. Respir Physiol Neurobiol 2005; 148:23-42. [PMID: 15967737 DOI: 10.1016/j.resp.2005.05.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Revised: 04/29/2005] [Accepted: 05/06/2005] [Indexed: 11/30/2022]
Abstract
Magnetic resonance imaging of the apparent diffusion coefficient (ADC) of hyperpolarized Helium-3 is a new technique for probing pulmonary microstructure in vivo. The aim of this study was the assessment of potential sources of systematic errors of the ADC measurement. The influence of macroscopic motion was determined by measurements at two different delays after initiating the breath-hold, and before and after cardiac arrest. An intercentre comparison was performed in two age- and lung function-matched groups of lung-healthy volunteers at two research sites. Moreover, measurements of diffusion anisotropy were performed. We found no dependency of the ADC as a function of the delay after stop of inspiration. The influence of cardiac motion was less than 10%. In the intercentre comparison study, an excellent agreement between the two sites was found. First measurements of the diffusion tensor of intrapulmonary Helium-3 are shown.
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Affiliation(s)
- Wolfgang G Schreiber
- Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University Medical School, Langenbeckstr. 1, 55131 Mainz, Germany.
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Wild JM, Fichele S, Woodhouse N, Paley MNJ, Kasuboski L, van Beek EJR. 3D volume-localized pO2 measurement in the human lung with 3He MRI. Magn Reson Med 2005; 53:1055-64. [PMID: 15844148 DOI: 10.1002/mrm.20423] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A method for 3D volume-localized quantification of pO2 in the lungs is presented that uses repetitive frame 3D gradient-echo imaging of (3)He. The method was demonstrated by experiments on (3)He phantoms containing known concentrations of O(2) and in vivo on a group of three healthy human volunteers. The results were compared with those obtained by equivalent 2D thin-slice and 2D projection methodologies, and were found to be consistent with published results from the 2D projection methodologies (pO(2) = 0.09-0.18 bar). Studies performed on the same subject, on three separate occasions, demonstrated a repeatability of pO(2) measurement to within 14% using the 3D technique. Experimental differences between the 2D and 3D methods were substantiated with theoretical and numerical analyses of the signal decay, which took into account the effects of out-of-slice diffusion as a source of error in the thin-slice 2D experiments. It is shown that the 2D thin-slice technique systematically underestimates pO2 when there is significant gas diffusion (factor of 4 underestimate for D = 0.9 cm(2)s(-1) representative of free (3)He in air).
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Affiliation(s)
- Jim M Wild
- Unit of Academic Radiology, University of Sheffield, UK.
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Gast KK, Schreiber WG, Herweling A, Lehmann F, Erdös G, Schmiedeskamp J, Kauczor HU, Eberle B. Two-dimensional and three-dimensional oxygen mapping by 3He-MRI validation in a lung phantom. Eur Radiol 2005; 15:1915-22. [PMID: 15856240 DOI: 10.1007/s00330-005-2778-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 04/04/2005] [Accepted: 04/07/2005] [Indexed: 11/30/2022]
Abstract
The aim of this study was to validate oxygen-sensitive 3He-MRI in noninvasive determination of the regional, two- and three-dimensional distribution of oxygen partial pressure. In a gas-filled elastic silicon ventilation bag used as a lung phantom, oxygen sensitive two- and three-dimensional 3He-MRI measurements were performed at different oxygen concentrations which had been equilibrated in a range of normal and pathologic values. The oxygen partial pressure distribution was determined from 3He-MRI using newly developed software allowing for mapping of oxygen partial pressure. The reference bulk oxygen partial pressure inside the phantom was measured by conventional respiratory gas analysis. In two-dimensional measurements, image-based and gas-analysis results correlated with r=0.98; in three-dimensional measurements the between-methods correlation coefficient was r=0.89. The signal-to-noise ratio of three-dimensional measurements was about half of that of two-dimensional measurements and became critical (below 3) in some data sets. Oxygen-sensitive 3He-MRI allows for noninvasive determination of the two- and three-dimensional distribution of oxygen partial pressure in gas-filled airspaces.
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Affiliation(s)
- Klaus Kurt Gast
- Department of Radiology, Johannes Gutenberg University Hospital, Langenbeckstrasse 1, 55131, Mainz, Germany.
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Abstract
Hyperpolarized gases belong to a new class of MR contrast agents that, when inhaled, provide high temporal and spatial resolution images of the lung airspaces. At this time, hyperpolarized gas MRI is only being performed at a limited number of institutions. However, the availability of hyperpolarized gas MRI could increase dramatically in coming years as regulatory hurdles within the U.S. are surmounted. The intent of this paper is to provide an introduction to hyperpolarized gas MRI for the thoracic radiologist. It includes a description of the basic principles of hyperpolarized gas MRI and a review of the results of preliminary clinical investigations with this method.
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Affiliation(s)
- Talissa A Altes
- Department of Radiology, University of Virginia, Charlottesville, VA 22908, USA.
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van Beek EJR, Wild JM, Kauczor HU, Schreiber W, Mugler JP, de Lange EE. Functional MRI of the lung using hyperpolarized 3-helium gas. J Magn Reson Imaging 2005; 20:540-54. [PMID: 15390146 DOI: 10.1002/jmri.20154] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Lung imaging has traditionally relied on x-ray methods, since proton MRI is limited to some extent by low proton density in the lung parenchyma and static field inhomogeneities in the chest. The relatively recent introduction of MRI of hyperpolarized noble gases has led to a rapidly evolving field of pulmonary MRI, revealing functional information of the lungs, which were hitherto unattainable. This review article briefly describes the physical background of the technology, and subsequently focuses on its clinical applications. Four different techniques that have been used in various human investigations are discussed: ventilation distribution, ventilation dynamics, and small airway evaluation using diffusion imaging and oxygen uptake assessment.
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Pérez-Sánchez JM, Pérez de Alejo R, Rodríguez I, Cortijo M, Peces-Barba G, Ruiz-Cabello J. In vivo diffusion weighted19F MRI using SF6. Magn Reson Med 2005; 54:460-3. [PMID: 16032667 DOI: 10.1002/mrm.20569] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Diffusion weighted 19F images of rat lung in vivo using SF6 are presented. Projection-reconstruction images were acquired by filling the rat lung with a mixture of SF6 and air, during 64 successive apneas. Each apnea lasted for 6 s, the time required to perform 100 accumulations of each k-space radial phase step for the five values of the diffusion gradient (TR = 10 ms). After diffusion images were acquired, an apparent diffusion coefficient (ADC) map was generated, yielding an average value for the ADC of 2.22 x 10(-6) m2/s and SD for ADC values of 1.27 x 10(-6) m2/s. To the best of our knowledge, this is the first in vivo diffusion weighting imaging application and the first ADC map obtained using 19F MRI.
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Affiliation(s)
- José M Pérez-Sánchez
- Instituto de Estudios Biofuncionales. Universidad Complutense de Madrid, Madrid, Spain.
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Hoffman EA, Clough AV, Christensen GE, Lin CL, McLennan G, Reinhardt JM, Simon BA, Sonka M, Tawhai MH, van Beek EJR, Wang G. The comprehensive imaging-based analysis of the lung: a forum for team science. Acad Radiol 2004; 11:1370-80. [PMID: 15596375 DOI: 10.1016/j.acra.2004.09.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Accepted: 09/28/2004] [Indexed: 11/20/2022]
Affiliation(s)
- Eric A Hoffman
- Department of Radiology, University of Iowa, 200 Hawkins Dr, Iowa City, IA 52242, USA.
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Ley S, Zaporozhan J, Morbach A, Eberle B, Gast KK, Heussel CP, Biedermann A, Mayer E, Schmiedeskamp J, Stepniak A, Schreiber WG, Kauczor HU. Functional evaluation of emphysema using diffusion-weighted 3Helium-magnetic resonance imaging, high-resolution computed tomography, and lung function tests. Invest Radiol 2004; 39:427-34. [PMID: 15194914 DOI: 10.1097/01.rli.0000129468.79005.1d] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To assess the emphysematous enlargement of distal airspaces and concomitant large and small airway disease using diffusion-weighted Helium-magnetic resonance imaging (MRI), high-resolution computed tomography (HRCT), and lung function tests (LFT). METHODS Seven patients were examined after single lung transplantation (LTx) and 1 before double LTx for various forms of emphysema. Five patients after double LTx served as controls. Patients were assessed by Helium-MRI (apparent diffusion coefficient [ADC]), HRCT (mean lung density [MLD], emphysema index [EI]), and LFT. RESULTS Transplanted lungs: mean ADC = 0.17 cm/s, MLD = -848 H, EI = 22%. Emphysematous lungs: mean ADC = 0.33 cm/s, MLD = -922 H; EI = 54%. Good correlations were found between ADC and MLD (r = 0.6), EI (r = 0.8), intrathoracic gas volume (r = 0.7), forced expiratory volume in 1 second (r = 0.7), and forced expiratory flows (r = 0.7). In contrast, HRCT only provided moderate correlations with LFT (EI: r = 0.5; MLD: r [le] 0.4). CONCLUSION In this initial study, He-MRI yield good correlations with HRCT and agrees better than HRCT with the functional characterization of emphysema regarding hyperinflation, large and small airway disease as provided by LFT.
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Affiliation(s)
- Sebastian Ley
- Department of Radiology, Johannes Gutenberg-University, Mainz, Germany.
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