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Foo CT, Langton D, Thompson BR, Thien F. Functional lung imaging using novel and emerging MRI techniques. Front Med (Lausanne) 2023; 10:1060940. [PMID: 37181360 PMCID: PMC10166823 DOI: 10.3389/fmed.2023.1060940] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 04/03/2023] [Indexed: 05/16/2023] Open
Abstract
Respiratory diseases are leading causes of death and disability in the world. While early diagnosis is key, this has proven difficult due to the lack of sensitive and non-invasive tools. Computed tomography is regarded as the gold standard for structural lung imaging but lacks functional information and involves significant radiation exposure. Lung magnetic resonance imaging (MRI) has historically been challenging due to its short T2 and low proton density. Hyperpolarised gas MRI is an emerging technique that is able to overcome these difficulties, permitting the functional and microstructural evaluation of the lung. Other novel imaging techniques such as fluorinated gas MRI, oxygen-enhanced MRI, Fourier decomposition MRI and phase-resolved functional lung imaging can also be used to interrogate lung function though they are currently at varying stages of development. This article provides a clinically focused review of these contrast and non-contrast MR imaging techniques and their current applications in lung disease.
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Affiliation(s)
- Chuan T. Foo
- Department of Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - David Langton
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
- Department of Thoracic Medicine, Peninsula Health, Frankston, VIC, Australia
| | - Bruce R. Thompson
- Melbourne School of Health Science, Melbourne University, Melbourne, VIC, Australia
| | - Francis Thien
- Department of Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
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2
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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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Loza LA, Kadlecek SJ, Pourfathi M, Hamedani H, Duncan IF, Ruppert K, Rizi RR. Quantification of Ventilation and Gas Uptake in Free-Breathing Mice With Hyperpolarized 129Xe MRI. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:2081-2091. [PMID: 30990426 PMCID: PMC7268199 DOI: 10.1109/tmi.2019.2911293] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Hyperpolarized 129Xe magnetic resonance imaging is a powerful modality capable of assessing lung structure and function. While it has shown promise as a clinical tool for the longitudinal assessment of lung function, its utility as an investigative tool for animal models of pulmonary diseases is limited by the necessity of invasive intubation and mechanical ventilation procedures. In this paper, we overcame this limitation by developing a gas delivery system and implementing a set of imaging schemes to acquire high-resolution gas- and dissolved-phase images in free-breathing mice. Gradient echo pulse sequences were used to acquire both high- and low-resolution gas-phase images, and regional fractional ventilation was quantified by comparing signal buildup among low-resolution gas-phase images acquired at two flip-angles. Dissolved-phase images were acquired using both ultra-short echo time and chemical shift imaging sequences with discrete sets of flip-angle/repetition time combinations to visualize gas uptake and distribution throughout the body. Spectral features distinct to various anatomical regions were identified in images acquired using the latter sequence and were used for the quantification of gas arrival times for respective compartments.
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Morgado F, Couch MJ, Stirrat E, Santyr G. Effect of T1relaxation on ventilation mapping using hyperpolarized129Xe multiple breath wash-out imaging. Magn Reson Med 2018; 80:2670-2680. [DOI: 10.1002/mrm.27234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 03/21/2018] [Accepted: 04/03/2018] [Indexed: 02/02/2023]
Affiliation(s)
- Felipe Morgado
- Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children; Toronto Ontario, Canada
- Department of Medical Biophysics; University of Toronto; Toronto Ontario, Canada
| | - Marcus J. Couch
- Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children; Toronto Ontario, Canada
- Department of Medical Biophysics; University of Toronto; Toronto Ontario, Canada
| | - Elaine Stirrat
- Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children; Toronto Ontario, Canada
| | - Giles Santyr
- Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children; Toronto Ontario, Canada
- Department of Medical Biophysics; University of Toronto; Toronto Ontario, Canada
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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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He M, Driehuys B, Que LG, Huang YCT. Using Hyperpolarized 129Xe MRI to Quantify the Pulmonary Ventilation Distribution. Acad Radiol 2016; 23:1521-1531. [PMID: 27617823 DOI: 10.1016/j.acra.2016.07.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/22/2016] [Accepted: 07/15/2016] [Indexed: 12/31/2022]
Abstract
RATIONALE AND OBJECTIVES Ventilation heterogeneity is impossible to detect with spirometry. Alternatively, pulmonary ventilation can be imaged three-dimensionally using inhaled 129Xe magnetic resonance imaging (MRI). To date, such images have been quantified primarily based on ventilation defects. Here, we introduce a robust means to transform 129Xe MRI scans such that the underlying ventilation distribution and its heterogeneity can be quantified. MATERIALS AND METHODS Quantitative 129Xe ventilation MRI was conducted in 12 younger (24.7 ± 5.2 years) and 10 older (62.2 ± 7.2 years) healthy individuals, as well as in 9 younger (25.9 ± 6.4 yrs) and 10 older (63.2 ± 6.1 years) asthmatics. The younger healthy population was used to establish a reference ventilation distribution and thresholds for six intensity bins. These bins were used to display and quantify the ventilation defect region (VDR), the low ventilation region (LVR), and the high ventilation region (HVR). RESULTS The ventilation distribution in young subjects was roughly Gaussian with a mean and standard deviation of 0.52 ± 0.18, resulting in VDR = 2.1 ± 1.3%, LVR = 15.6 ± 5.4%, and HVR = 17.4 ± 3.1%. Older healthy volunteers exhibited a significantly right-skewed distribution (0.46 ± 0.20, P = 0.034), resulting in significantly increased VDR (7.0 ± 4.8%, P = 0.008) and LVR (24.5 ± 11.5%, P = 0.025). In the asthmatics, VDR and LVR increased in the older population, and HVR was significantly reduced (13.5 ± 4.6% vs 18.9 ± 4.5%, P = 0.009). Quantitative 129Xe MRI also revealed altered ventilation heterogeneity in response to albuterol in two asthmatics with normal spirometry. CONCLUSIONS Quantitative 129Xe MRI provides a robust and objective means to display and quantify the pulmonary ventilation distribution, even in subjects who have airway function impairment not appreciated by spirometry.
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Walkup LL, Thomen RP, Akinyi T, Watters E, Ruppert K, Clancy JP, Woods JC, Cleveland ZI. Feasibility, tolerability and safety of pediatric hyperpolarized 129Xe magnetic resonance imaging in healthy volunteers and children with cystic fibrosis. Pediatr Radiol 2016; 46:1651-1662. [PMID: 27492388 PMCID: PMC5083137 DOI: 10.1007/s00247-016-3672-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 06/05/2016] [Accepted: 07/20/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Hyperpolarized 129Xe is a promising contrast agent for MRI of pediatric lung function, but its safety and tolerability in children have not been rigorously assessed. OBJECTIVE To assess the feasibility, safety and tolerability of hyperpolarized 129Xe gas as an inhaled contrast agent for pediatric pulmonary MRI in healthy control subjects and in children with cystic fibrosis. MATERIALS AND METHODS Seventeen healthy control subjects (ages 6-15 years, 11 boys) and 11 children with cystic fibrosis (ages 8-16 years, 4 boys) underwent 129Xe MRI, receiving up to three doses of 129Xe gas prepared by either a commercially available or a homebuilt 129Xe polarizer. Subject heart rate and SpO2 were monitored for 2 min post inhalation and compared to resting baseline values. Adverse events were reported via follow-up phone call at days 1 and 30 (range ±7 days) post-MRI. RESULTS All children tolerated multiple doses of 129Xe, and no children withdrew from the study. Relative to baseline, most children who received a full dose of gas for imaging (10 of 12 controls and 8 of 11 children with cystic fibrosis) experienced a nadir in SpO2 (mean -6.0 ± standard deviation 7.2%, P≤0.001); however within 2 min post inhalation SpO2 values showed no significant difference from baseline (P=0.11). There was a slight elevation in heart rate (mean +6.6 ± 13.9 beats per minute [bpm], P=0.021), which returned from baseline within 2 min post inhalation (P=0.35). Brief side effects related to the anesthetic properties of xenon were mild and quickly resolved without intervention. No serious or severe adverse events were observed; in total, four minor adverse events (14.3%) were reported following 129Xe MRI, but all were deemed unrelated to the study. CONCLUSION The feasibility, safety and tolerability of 129Xe MRI has been assessed in a small group of children as young as 6 years. SpO2 changes were consistent with the expected physiological effects of a short anoxic breath-hold, and other mild side effects were consistent with the known anesthetic properties of xenon and with previous safety assessments of 129Xe MRI in adults. Hyperpolarized 129Xe is a safe and well-tolerated inhaled contrast agent for pulmonary MR imaging in healthy children and in children with cystic fibrosis who have mild to moderate lung disease.
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Affiliation(s)
- Laura L. Walkup
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA
| | - Robert P. Thomen
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA,Department of Physics, Washington University in St. Louis, St. Louis, MO, USA
| | - Teckla Akinyi
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA,Biomedical Engineering Program, University of Cincinnati, Cincinnati, OH, USA
| | - Erin Watters
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA
| | - Kai Ruppert
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA
| | - John P. Clancy
- Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Jason C. Woods
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA,Department of Physics, Washington University in St. Louis, St. Louis, MO, USA
| | - Zackary I. Cleveland
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC 5033, Cincinnati, OH 45229, USA,Biomedical Engineering Program, University of Cincinnati, Cincinnati, OH, USA
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8
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Lilburn DML, Tatler AL, Six JS, Lesbats C, Habgood A, Porte J, Hughes-Riley T, Shaw DE, Jenkins G, Meersmann T. Investigating lung responses with functional hyperpolarized xenon-129 MRI in an ex vivo rat model of asthma. Magn Reson Med 2016; 76:1224-35. [PMID: 26507239 PMCID: PMC5026173 DOI: 10.1002/mrm.26003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 08/26/2015] [Accepted: 09/08/2015] [Indexed: 01/08/2023]
Abstract
PURPOSE Asthma is a disease of increasing worldwide importance that calls for new investigative methods. Ex vivo lung tissue is being increasingly used to study functional respiratory parameters independent of confounding systemic considerations but also to reduce animal numbers and associated research costs. In this work, a straightforward laboratory method is advanced to probe dynamic changes in gas inhalation patterns by using an ex vivo small animal ovalbumin (OVA) model of human asthma. METHODS Hyperpolarized (hp) (129) Xe was actively inhaled by the excised lungs exposed to a constant pressure differential that mimicked negative pleural cavity pressure. The method enabled hp (129) Xe MRI of airway responsiveness to intravenous methacholine (MCh) and airway challenge reversal through salbutamol. RESULTS Significant differences were demonstrated between control and OVA challenged animals on global lung hp (129) Xe gas inhalation with P < 0.05 at MCh dosages above 460 μg. Spatial mapping of the regional hp gas distribution revealed an approximately three-fold increase in heterogeneity for the asthma model organs. CONCLUSION The experimental results from this proof of concept work suggest that the ex vivo hp noble gas imaging arrangement and the applied image analysis methodology may be useful as an adjunct to current diagnostic techniques. Magn Reson Med 76:1224-1235, 2016. © 2015 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)
- David M L Lilburn
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Amanda L Tatler
- Division of Respiratory Medicine, Nottingham University Hospitals, City Campus, University of Nottingham, Nottingham, United Kingdom
| | - Joseph S Six
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Clémentine Lesbats
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Anthony Habgood
- Division of Respiratory Medicine, Nottingham University Hospitals, City Campus, University of Nottingham, Nottingham, United Kingdom
| | - Joanne Porte
- Division of Respiratory Medicine, Nottingham University Hospitals, City Campus, University of Nottingham, Nottingham, United Kingdom
| | - Theodore Hughes-Riley
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Dominick E Shaw
- Division of Respiratory Medicine, Nottingham University Hospitals, City Campus, University of Nottingham, Nottingham, United Kingdom
| | - Gisli Jenkins
- Division of Respiratory Medicine, Nottingham University Hospitals, City Campus, University of Nottingham, Nottingham, United Kingdom
| | - Thomas Meersmann
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom.
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Horn FC, Rao M, Stewart NJ, Wild JM. Multiple breath washout of hyperpolarized 129 Xe and 3 He in human lungs with three-dimensional balanced steady-state free-precession imaging. Magn Reson Med 2016; 77:2288-2295. [PMID: 27404992 PMCID: PMC5484367 DOI: 10.1002/mrm.26319] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 05/25/2016] [Accepted: 05/30/2016] [Indexed: 01/31/2023]
Abstract
Purpose To compare quantitative fractional ventilation measurements from multiple breath washout imaging (MBW‐I) using hyperpolarized 3He with both spoiled gradient echo (SPGR) and balanced steady‐state free precession (bSSFP) three‐dimensional (3D) pulse sequences and to evaluate the feasibility of MBW‐I with hyperpolarized 129Xe. Methods Seven healthy subjects were scanned using 3He MBW‐I with 3D SPGR and bSSFP sequences. Five also underwent MBW‐I with 129Xe. A dual‐tuned coil was used to acquire MBW‐I data from both nuclei in the same subject position, enabling direct comparison of regional information. Results High‐quality MBW images were obtained with bSSFP sequences using a reduced dose (100 mL) of inhaled hyperpolarized 3He. 3D MBW‐I with 129Xe was also successfully demonstrated with a bSSFP sequence. Regional quantitative ventilation measures derived from 3He and 129Xe MBW‐I correlated well in all subjects (P < 0.001) with mean Pearson's correlation coefficients of r = 0.61 and r = 0.52 for 3He SPGR‐bSSFP and 129Xe‐3He (bSSFP) comparisons. The average intersubject mean difference (and standard deviation) in fractional ventilation in SPGR‐bSSFP and 129Xe‐3He comparisons was 15% (28%) and 9% (38%), respectively. Conclusions Improved sensitivity in MBW‐I can be achieved with polarization‐efficient bSSFP sequences. Same scan‐session 3D MBW‐I with 3He and 129Xe has been demonstrated using a dual‐tuned coil. Magn Reson Med 77:2288–2295, 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)
- Felix C Horn
- POLARIS, Unit of Academic Radiology, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Madhwesha Rao
- POLARIS, Unit of Academic Radiology, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Neil J Stewart
- POLARIS, Unit of Academic Radiology, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Jim M Wild
- POLARIS, Unit of Academic Radiology, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.,Insigneo Institute of In-Silico Medicine, University of Sheffield, Sheffield, United Kingdom
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Couch MJ, Fox MS, Viel C, Gajawada G, Li T, Ouriadov AV, Albert MS. Fractional ventilation mapping using inert fluorinated gas MRI in rat models of inflammation and fibrosis. NMR IN BIOMEDICINE 2016; 29:545-552. [PMID: 26866511 DOI: 10.1002/nbm.3493] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 12/11/2015] [Accepted: 01/01/2016] [Indexed: 06/05/2023]
Abstract
The purpose of this study was to extend established methods for fractional ventilation mapping using (19) F MRI of inert fluorinated gases to rat models of pulmonary inflammation and fibrosis. In this study, five rats were instilled with lipopolysaccharide (LPS) in the lungs two days prior to imaging, six rats were instilled with bleomycin in the lungs two weeks prior to imaging and an additional four rats were used as controls. (19) F MR lung imaging was performed at 3 T with rats continuously breathing a mixture of sulfur hexafluoride and O2 . Fractional ventilation maps were obtained using a wash-out approach, by switching the breathing mixture to pure O2 , and acquiring images following each successive wash-out breath. The mean fractional ventilation (r) was 0.29 ± 0.05 for control rats, 0.23 ± 0.10 for LPS-instilled rats and 0.19 ± 0.03 for bleomycin-instilled rats. Bleomycin-instilled rats had a significantly decreased mean r value compared with controls (P = 0.010). Although LPS-instilled rats had a slightly reduced mean r value, this trend was not statistically significant (P = 0.556). Fractional ventilation gradients were calculated in the anterior/posterior (A/P) direction, and the mean A/P gradient was -0.005 ± 0.008 cm(-1) for control rats, 0.013 ± 0.005 cm(-1) for LPS-instilled rats and 0.009 ± 0.018 cm(-1) for bleomycin-instilled rats. Fractional ventilation gradients were significantly different for control rats compared with LPS-instilled rats only (P = 0.016). The ventilation gradients calculated from control rats showed the expected gravitational relationship, while ventilation gradients calculated from LPS- and bleomycin-instilled rats showed the opposite trend. Histology confirmed that LPS-instilled rats had a significantly elevated alveolar wall thickness, while bleomycin-instilled rats showed signs of substantial fibrosis. Overall, (19)F MRI may be able to detect the effects of pulmonary inflammation and fibrosis using a simple and inexpensive imaging approach that can potentially be translated to humans.
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Affiliation(s)
- Marcus J Couch
- Lakehead University, Thunder Bay, Ontario, Canada
- Thunder Bay Regional Research Institute, Thunder Bay, Ontario, Canada
| | - Matthew S Fox
- Robarts Research Institute, Western University, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Chris Viel
- Lakehead University, Thunder Bay, Ontario, Canada
- Thunder Bay Regional Research Institute, Thunder Bay, Ontario, Canada
| | - Gowtham Gajawada
- Lakehead University, Thunder Bay, Ontario, Canada
- Thunder Bay Regional Research Institute, Thunder Bay, Ontario, Canada
| | - Tao Li
- Lakehead University, Thunder Bay, Ontario, Canada
- Thunder Bay Regional Research Institute, Thunder Bay, Ontario, Canada
| | - Alexei V Ouriadov
- Robarts Research Institute, Western University, London, Ontario, Canada
| | - Mitchell S Albert
- Lakehead University, Thunder Bay, Ontario, Canada
- Thunder Bay Regional Research Institute, Thunder Bay, Ontario, Canada
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11
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Stewart NJ, Wild JM. MRI methods for structural and functional assessment of the lungs: proton and multinuclear. IMAGING 2016. [DOI: 10.1183/2312508x.10002115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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12
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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: 80] [Impact Index Per Article: 10.0] [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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Hamedani H, Clapp JT, Kadlecek SJ, Emami K, Ishii M, Gefter WB, Xin Y, Cereda M, Shaghaghi H, Siddiqui S, Rossman MD, Rizi RR. Regional Fractional Ventilation by Using Multibreath Wash-in (3)He MR Imaging. Radiology 2016; 279:917-24. [PMID: 26785042 DOI: 10.1148/radiol.2015150495] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To assess the feasibility and optimize the accuracy of the multibreath wash-in hyperpolarized helium 3 ((3)He) approach to ventilation measurement by using magnetic resonance (MR) imaging as well as to examine the physiologic differences that this approach reveals among nonsmokers, asymptomatic smokers, and patients with chronic obstructive pulmonary disease (COPD). Materials and Methods All experiments were approved by the local institutional review board and compliant with HIPAA. Informed consent was obtained from all subjects. To measure fractional ventilation, the authors administered a series of identical normoxic hyperpolarized gas breaths to the subject; after each inspiration, an image was acquired during a short breath hold. Signal intensity buildup was fit to a recursive model that regionally solves for fractional ventilation. This measurement was successfully performed in nine subjects: three healthy nonsmokers (one man, two women; mean age, 45 years ± 4), three asymptomatic smokers (three men; mean age, 51 years ± 5), and three patients with COPD (three men; mean age, 59 years ± 5). Repeated measures analysis of variance was performed, followed by post hoc tests with Bonferroni correction, to assess the differences among the three cohorts. Results Whole-lung fractional ventilation as measured with hyperpolarized (3)He in all subjects (mean, 0.24 ± 0.06) showed a strong correlation with global fractional ventilation as measured with a gas delivery device (R(2) = 0.96, P < .001). Significant differences between the means of whole-lung fractional ventilation (F2,10 = 7.144, P = .012) and fractional ventilation heterogeneity (F2,10 = 7.639, P = .010) were detected among cohorts. In patients with COPD, the protocol revealed regions wherein fractional ventilation varied substantially over multiple breaths. Conclusion Multibreath wash-in hyperpolarized (3)He MR imaging of fractional ventilation is feasible in human subjects and demonstrates very good global (whole-lung) precision. Fractional ventilation measurement with this physiologically realistic approach reveals significant differences between patients with COPD and healthy subjects. To minimize error, several sources of potential bias must be corrected when calculating fractional ventilation. (©) RSNA, 2016 Online supplemental material is available for this article.
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Affiliation(s)
- Hooman Hamedani
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Justin T Clapp
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Stephen J Kadlecek
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Kiarash Emami
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Masaru Ishii
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Warren B Gefter
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Yi Xin
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Maurizio Cereda
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Hoora Shaghaghi
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Sarmad Siddiqui
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Milton D Rossman
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
| | - Rahim R Rizi
- From the Department of Radiology (H.H., J.T.C., S.J.K., K.E., M.I., W.B.G., Y.X., H.S., S.S., R.R.R.), Department of Anesthesiology and Critical Care (M.C.), and Pulmonary, Allergy and Critical Care Division (M.D.R.), University of Pennsylvania, 308 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104
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Cereda M, Xin Y, Hamedani H, Clapp J, Kadlecek S, Meeder N, Zeng J, Profka H, Kavanagh BP, Rizi RR. Mild loss of lung aeration augments stretch in healthy lung regions. J Appl Physiol (1985) 2015; 120:444-54. [PMID: 26662053 DOI: 10.1152/japplphysiol.00734.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 12/07/2015] [Indexed: 11/22/2022] Open
Abstract
Inspiratory stretch by mechanical ventilation worsens lung injury. However, it is not clear whether and how the ventilator damages lungs in the absence of preexisting injury. We hypothesized that subtle loss of lung aeration during general anesthesia regionally augments ventilation and distension of ventilated air spaces. In eight supine anesthetized and intubated rats, hyperpolarized gas MRI was performed after a recruitment maneuver following 1 h of volume-controlled ventilation with zero positive end-expiratory pressure (ZEEP), FiO2 0.5, and tidal volume 10 ml/kg, and after a second recruitment maneuver. Regional fractional ventilation (FV), apparent diffusion coefficient (ADC) of (3)He (a measurement of ventilated peripheral air space dimensions), and gas volume were measured in lung quadrants of ventral and dorsal regions of the lungs. In six additional rats, computed tomography (CT) images were obtained at each time point. Ventilation with ZEEP decreased total lung gas volume and increased both FV and ADC in all studied regions. Increases in FV were more evident in the dorsal slices. In each lung quadrant, higher ADC was predicted by lower gas volume and by increased mean values (and heterogeneity) of FV distribution. CT scans documented 10% loss of whole-lung aeration and increased density in the dorsal lung, but no macroscopic atelectasis. Loss of pulmonary gas at ZEEP increased fractional ventilation and inspiratory dimensions of ventilated peripheral air spaces. Such regional changes could help explain a propensity for mechanical ventilation to contribute to lung injury in previously uninjured lungs.
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Affiliation(s)
- Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Justin Clapp
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Natalie Meeder
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Johnathan Zeng
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Brian P Kavanagh
- Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
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15
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Imai H, Matsumoto H, Miyakoshi E, Okumura S, Fujiwara H, Kimura A. Regional fractional ventilation mapping in spontaneously breathing mice using hyperpolarized ¹²⁹Xe MRI. NMR IN BIOMEDICINE 2015; 28:24-29. [PMID: 25312654 DOI: 10.1002/nbm.3222] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 08/20/2014] [Accepted: 08/29/2014] [Indexed: 06/04/2023]
Abstract
The feasibility of ventilation imaging with hyperpolarized (HP) (129) Xe MRI has been investigated for quantitative and regional assessment of ventilation in spontaneously breathing mice. The multiple breath ventilation imaging technique was modified to the protocol of spontaneous inhalation of HP (129) Xe delivered continuously from a (129) Xe polarizer. A series of (129) Xe ventilation images was obtained by varying the number of breaths before the (129) Xe lung imaging. The fractional ventilation, r, was successfully evaluated for spontaneously breathing mice. An attempt was made to detect ventilation dysfunction in the emphysematous mouse lung induced by intratracheal administration of porcine pancreatic elastase (PPE). As a result, the distribution of fractional ventilation could be visualized by the r map. Significant dysfunction of ventilation was quantitatively identified in the PPE-treated group. The whole-lung r value of 0.34 ± 0.01 for control mice (N = 4) was significantly reduced, to 0.25 ± 0.07, in PPE-treated mice (N = 4) (p = 0.038). This study is the first application of multiple breath ventilation imaging to spontaneously breathing mice, and shows that this methodology is sensitive to differences in the pulmonary ventilation. This methodology is expected to improve simplicity as well as noninvasiveness when assessing regional ventilation in small rodents.
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Affiliation(s)
- Hirohiko Imai
- Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan; Division of Systems Informatics, Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan
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16
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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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17
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18
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Ouriadov AV, Fox MS, Couch MJ, Li T, Ball IK, Albert MS. In vivo regional ventilation mapping using fluorinated gas MRI with an x-centric FGRE method. Magn Reson Med 2014; 74:550-7. [DOI: 10.1002/mrm.25406] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 07/20/2014] [Accepted: 07/22/2014] [Indexed: 11/09/2022]
Affiliation(s)
| | - Matthew S. Fox
- Thunder Bay Regional Research Institute; Thunder Bay Canada
| | - Marcus J. Couch
- Thunder Bay Regional Research Institute; Thunder Bay Canada
- Lakehead University; Thunder Bay Canada
| | - Tao Li
- Thunder Bay Regional Research Institute; Thunder Bay Canada
| | - Iain K. Ball
- Thunder Bay Regional Research Institute; Thunder Bay Canada
| | - Mitchell S. Albert
- Thunder Bay Regional Research Institute; Thunder Bay Canada
- Lakehead University; Thunder Bay Canada
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19
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Horn FC, Deppe MH, Marshall H, Parra-Robles J, Wild JM. Quantification of regional fractional ventilation in human subjects by measurement of hyperpolarized 3He washout with 2D and 3D MRI. J Appl Physiol (1985) 2013; 116:129-39. [PMID: 24311749 DOI: 10.1152/japplphysiol.00378.2013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple-breath washout hyperpolarized (3)He MRI was used to calculate regional parametric images of fractional ventilation (r) as the ratio of fresh gas entering a volume unit to the total end inspiratory volume of the unit. Using a single dose of inhaled hyperpolarized gas and a total acquisition time of under 1 min, gas washout was measured by dynamic acquisitions during successive breaths with a fixed delay. A two-dimensional (2D) imaging protocol was investigated in four healthy subjects in the supine position, and in a second protocol the capability of extending the washout imaging to a three-dimensional (3D) acquisition covering the whole lungs was tested. During both protocols, subjects were breathing comfortably, only restricted by synchronization of breathing to the sequence timings. The 3D protocol was also successfully tested on one patient with cystic fibrosis. Mean r values from each volunteer were compared with global gas volume turnover, as calculated from flow measurement at the mouth divided by total lung volume (from MRI images), and a significant correlation (r = 0.74, P < 0.05) was found. The effects of gravity on R were investigated, and an average decrease in r of 5.5%/cm (Δr = 0.016 ± 0.006 cm(-1)) from posterior to anterior was found in the right lung. Intersubject reproducibility of r imaging with the 2D and 3D protocol was tested, and a significant correlation between repeated experiments was found in a pixel-by-pixel comparison. The proposed methods can be used to measure r on a regional basis.
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Affiliation(s)
- Felix C Horn
- Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom
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20
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Kadlecek S, Hamedani H, Xu Y, Emami K, Xin Y, Ishii M, Rizi R. Regional alveolar partial pressure of oxygen measurement with parallel accelerated hyperpolarized gas MRI. Acad Radiol 2013; 20:1224-33. [PMID: 24029054 DOI: 10.1016/j.acra.2013.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/19/2013] [Accepted: 07/03/2013] [Indexed: 11/16/2022]
Abstract
RATIONALE AND OBJECTIVES Alveolar oxygen tension (Pao2) is sensitive to the interplay between local ventilation, perfusion, and alveolar-capillary membrane permeability, and thus reflects physiologic heterogeneity of healthy and diseased lung function. Several hyperpolarized helium ((3)He) magnetic resonance imaging (MRI)-based Pao2 mapping techniques have been reported, and considerable effort has gone toward reducing Pao2 measurement error. We present a new Pao2 imaging scheme, using parallel accelerated MRI, which significantly reduces measurement error. MATERIALS AND METHODS The proposed Pao2 mapping scheme was computer-simulated and was tested on both phantoms and five human subjects. Where possible, correspondence between actual local oxygen concentration and derived values was assessed for both bias (deviation from the true mean) and imaging artifact (deviation from the true spatial distribution). RESULTS Phantom experiments demonstrated a significantly reduced coefficient of variation using the accelerated scheme. Simulation results support this observation and predict that correspondence between the true spatial distribution and the derived map is always superior using the accelerated scheme, although the improvement becomes less significant as the signal-to-noise ratio increases. Paired measurements in the human subjects, comparing accelerated and fully sampled schemes, show a reduced Pao2 distribution width for 41 of 46 slices. CONCLUSION In contrast to proton MRI, acceleration of hyperpolarized imaging has no signal-to-noise penalty; its use in Pao2 measurement is therefore always beneficial. Comparison of multiple schemes shows that the benefit arises from a longer time-base during which oxygen-induced depolarization modifies the signal strength. Demonstration of the accelerated technique in human studies shows the feasibility of the method and suggests that measurement error is reduced here as well, particularly at low signal-to-noise levels.
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Affiliation(s)
- Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, 308C Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104.
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21
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Mugler JP, Altes TA. Hyperpolarized 129Xe MRI of the human lung. J Magn Reson Imaging 2013; 37:313-31. [PMID: 23355432 DOI: 10.1002/jmri.23844] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Accepted: 08/29/2012] [Indexed: 11/07/2022] Open
Abstract
By permitting direct visualization of the airspaces of the lung, magnetic resonance imaging (MRI) using hyperpolarized gases provides unique strategies for evaluating pulmonary structure and function. Although the vast majority of research in humans has been performed using hyperpolarized (3)He, recent contraction in the supply of (3)He and consequent increases in price have turned attention to the alternative agent, hyperpolarized (129) Xe. Compared to (3)He, (129)Xe yields reduced signal due to its smaller magnetic moment. Nonetheless, taking advantage of advances in gas-polarization technology, recent studies in humans using techniques for measuring ventilation, diffusion, and partial pressure of oxygen have demonstrated results for hyperpolarized (129)Xe comparable to those previously demonstrated using hyperpolarized (3)He. In addition, xenon has the advantage of readily dissolving in lung tissue and blood following inhalation, which makes hyperpolarized (129)Xe particularly attractive for exploring certain characteristics of lung function, such as gas exchange and uptake, which cannot be accessed using (3)He. Preliminary results from methods for imaging (129) Xe dissolved in the human lung suggest that these approaches will provide new opportunities for quantifying relationships among gas delivery, exchange, and transport, and thus show substantial potential to broaden our understanding of lung disease. Finally, recent changes in the commercial landscape of the hyperpolarized-gas field now make it possible for this innovative technology to move beyond the research laboratory.
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Affiliation(s)
- John P Mugler
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
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22
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Jacob RE, Carson JP, Thomas M, Einstein DR. Dynamic multiscale boundary conditions for 4D CT of healthy and emphysematous rats. PLoS One 2013; 8:e65874. [PMID: 23799057 PMCID: PMC3683027 DOI: 10.1371/journal.pone.0065874] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 04/29/2013] [Indexed: 11/30/2022] Open
Abstract
Changes in the shape of the lung during breathing determine the movement of airways and alveoli, and thus impact airflow dynamics. Modeling airflow dynamics in health and disease is a key goal for predictive multiscale models of respiration. Past efforts to model changes in lung shape during breathing have measured shape at multiple breath-holds. However, breath-holds do not capture hysteretic differences between inspiration and expiration resulting from the additional energy required for inspiration. Alternatively, imaging dynamically--without breath-holds--allows measurement of hysteretic differences. In this study, we acquire multiple micro-CT images per breath (4DCT) in live rats, and from these images we develop, for the first time, dynamic volume maps. These maps show changes in local volume across the entire lung throughout the breathing cycle and accurately predict the global pressure-volume (PV) hysteresis. Male Sprague-Dawley rats were given either a full- or partial-lung dose of elastase or saline as a control. After three weeks, 4DCT images of the mechanically ventilated rats under anesthesia were acquired dynamically over the breathing cycle (11 time points, ≤100 ms temporal resolution, 8 cmH2O peak pressure). Non-rigid image registration was applied to determine the deformation gradient--a numerical description of changes to lung shape--at each time point. The registration accuracy was evaluated by landmark identification. Of 67 landmarks, one was determined misregistered by all three observers, and 11 were determined misregistered by two observers. Volume change maps were calculated on a voxel-by-voxel basis at all time points using both the Jacobian of the deformation gradient and the inhaled air fraction. The calculated lung PV hysteresis agrees with pressure-volume curves measured by the ventilator. Volume maps in diseased rats show increased compliance and ventilation heterogeneity. Future predictive multiscale models of rodent respiration may leverage such volume maps as boundary conditions.
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Affiliation(s)
- Richard E Jacob
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
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23
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Emami K, Xu Y, Hamedani H, Profka H, Kadlecek S, Xin Y, Ishii M, Rizi RR. Accelerated fractional ventilation imaging with hyperpolarized Gas MRI. Magn Reson Med 2013; 70:1353-9. [PMID: 23400938 DOI: 10.1002/mrm.24582] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 10/24/2012] [Accepted: 11/12/2012] [Indexed: 11/11/2022]
Abstract
PURPOSE To investigate the utility of accelerated imaging to enhance multibreath fractional ventilation (r) measurement accuracy using hyperpolarized gas MRI. Undersampling shortens the breath-hold time, thereby reducing the O2 -induced signal decay and allows subjects to maintain a more physiologically relevant breathing pattern. Additionally, it may improve r estimation accuracy by reducing radiofrequency destruction of hyperpolarized gas. METHODS Image acceleration was achieved using an eight-channel phased array coil. Undersampled image acquisition was simulated in a series of ventilation images and data was reconstructed for various matrix sizes (48-128) using generalized auto-calibrating partially parallel acquisition. Parallel accelerated r imaging was also performed on five mechanically ventilated pigs. RESULTS Optimal acceleration factor was fairly invariable (2.0-2.2×) over the range of simulated resolutions. Estimation accuracy progressively improved with higher resolutions (39-51% error reduction). In vivo r values were not significantly different between the two methods: 0.27 ± 0.09, 0.35 ± 0.06, 0.40 ± 0.04 (standard) versus 0.23 ± 0.05, 0.34 ± 0.03, 0.37 ± 0.02 (accelerated); for anterior, medial, and posterior slices, respectively, whereas the corresponding vertical r gradients were significant (P < 0.001): 0.021 ± 0.007 (standard) versus 0.019 ± 0.005 (accelerated) (cm(-1) ). CONCLUSION Quadruple phased array coil simulations resulted in an optimal acceleration factor of ∼2× independent of imaging resolution. Results advocate undersampled image acceleration to improve accuracy of fractional ventilation measurement with hyperpolarized gas MRI.
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Affiliation(s)
- Kiarash Emami
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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24
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Emami K, Xu Y, Hamedani H, Xin Y, Profka H, Rajaei J, Kadlecek S, Ishii M, Rizi RR. Multislice fractional ventilation imaging in large animals with hyperpolarized gas MRI. NMR IN BIOMEDICINE 2012; 25:1015-1025. [PMID: 22290603 PMCID: PMC3362674 DOI: 10.1002/nbm.2763] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 11/17/2011] [Accepted: 11/22/2011] [Indexed: 05/31/2023]
Abstract
The noninvasive assessment of regional lung ventilation is of critical importance in the quantification of the severity of disease and evaluation of response to therapy in many pulmonary diseases. This work presents, for the first time, the implementation of a hyperpolarized (HP) gas MRI technique to measure whole-lung regional fractional ventilation (r) in Yorkshire pigs (n = 5) through the use of a gas mixing and delivery device in the supine position. The proposed technique utilizes a series of back-to-back HP gas breaths with images acquired during short end-inspiratory breath-holds. In order to decouple the radiofrequency pulse decay effect from the ventilatory signal build-up in the airways, the regional distribution of the flip angle (α) was estimated in the imaged slices by acquiring a series of back-to-back images with no interscan time delay during a breath-hold at the tail end of the ventilation sequence. Analysis was performed to assess the sensitivity of the multislice ventilation model to noise, oxygen and the number of flip angle images. The optimal α value was determined on the basis of the minimization of the error in r estimation: α(opt) = 5-6º for the set of acquisition parameters in pigs. The mean r values for the group of pigs were 0.27 ± 0.09, 0.35 ± 0.06 and 0.40 ± 0.04 for the ventral, middle and dorsal slices, respectively (excluding conductive airways r 0.9). A positive gravitational (ventral-dorsal) ventilation gradient effect was present in all animals. The trachea and major conductive airways showed a uniform near-unity r value, with progressively smaller values corresponding to smaller diameter airways, and ultimately leading to lung parenchyma. The results demonstrate the feasibility of the measurement of the fractional ventilation in large species, and provide a platform to address the technical challenges associated with long breathing time scales through the optimization of acquisition parameters in species with a pulmonary physiology very similar to that of humans.
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Affiliation(s)
- Kiarash Emami
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Carrero-González L, Kaulisch T, Ruiz-Cabello J, Pérez-Sánchez JM, Peces-Barba G, Stiller D, Rodríguez I. Apparent diffusion coefficient of hyperpolarized (3)He with minimal influence of the residual gas in small animals. NMR IN BIOMEDICINE 2012; 25:1026-1032. [PMID: 22275333 DOI: 10.1002/nbm.2765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 11/16/2011] [Accepted: 11/22/2011] [Indexed: 05/31/2023]
Abstract
The apparent diffusion coefficient (ADC) of hyperpolarized (HP) gases is a parameter that reflects changes in lung microstructure. However, ADC is dependent on many physiological and experimental variables that need to be controlled or specified in order to ensure the reliability and reproducibility of this parameter. A single breath-hold experiment is desirable in order to reduce the amount of consumed HP gas. The application of a positive end-expiratory pressure (PEEP) causes an increase in the residual gas volume. Depending on the applied PEEP, the ratio between the incoming and residual gas volumes will change and the ADC will vary, as long as both gases do not have the same diffusion coefficient. The most standard method for human applications uses air for breathing and a bolus of pure HP (3)He for MRI data acquisition. By applying this method in rats, we have demonstrated that ADC values are strongly dependent on the applied PEEP, and therefore on the residual gas volume in the lung. This outcome will play an important role in studies concerning certain diseases, such as emphysema, which is characterized by an increase in the residual volume. Ventilation with an oxygen-helium mixture (VOHeM) is a proposed single breath-hold method that uses two different gas mixtures (O(2)-(4)He for ventilation and HP (3)He-N(2) for imaging). The concentration of each gas in its respective mixture was calculated in order to obtain the same diffusion coefficient in both mixtures. ADCs obtained from VOHeM are independent of PEEP, thus minimizing the effect of the different residual volumes.
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Affiliation(s)
- L Carrero-González
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
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Schnidrig S, Casaulta C, Schibler A, Riedel T. Influence of end-expiratory level and tidal volume on gravitational ventilation distribution during tidal breathing in healthy adults. Eur J Appl Physiol 2012; 113:591-8. [PMID: 22872368 DOI: 10.1007/s00421-012-2469-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 07/25/2012] [Indexed: 10/27/2022]
Abstract
Our understanding of regional filling of the lung and regional ventilation distribution is based on studies using stepwise inhalation of radiolabelled tracer gases, magnetic resonance imaging and positron emission tomography. We aimed to investigate whether these differences in ventilation distribution at different end-expiratory levels (EELs) and tidal volumes (V (T)s) held also true during tidal breathing. Electrical impedance tomography (EIT) measurements were performed in ten healthy adults in the right lateral position. Five different EELs with four different V (T)s at each EEL were tested in random order, resulting in 19 combinations. There were no measurements for the combination of the highest EEL/highest V (T). EEL and V (T) were controlled by visual feedback based on airflow. The fraction of ventilation directed to different slices of the lung (VENT(RL1)-VENT(RL8)) and the rate of the regional filling of each slice versus the total lung were analysed. With increasing EEL but normal tidal volume, ventilation was preferentially distributed to the dependent lung and the filling of the right and left lung was more homogeneous. With increasing V (T) and maintained normal EEL (FRC), ventilation was preferentially distributed to the dependent lung and regional filling became more inhomogeneous (p < 0.05). We could demonstrate that regional and temporal ventilation distribution during tidal breathing was highly influenced by EEL and V (T).
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Affiliation(s)
- Silvia Schnidrig
- Division of Paediatric and Neonatal Intensive Care Medicine, Department of Paediatrics, Inselspital, University Children's Hospital and University of Bern, 3010 Bern, Switzerland
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Couch MJ, Ouriadov A, Santyr GE. Regional ventilation mapping of the rat lung using hyperpolarized129Xe magnetic resonance imaging. Magn Reson Med 2012; 68:1623-31. [DOI: 10.1002/mrm.24152] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 11/17/2011] [Accepted: 12/14/2011] [Indexed: 11/11/2022]
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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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Imai H, Kimura A, Hori Y, Iguchi S, Kitao T, Okubo E, Ito T, Matsuzaki T, Fujiwara H. Hyperpolarized 129Xe lung MRI in spontaneously breathing mice with respiratory gated fast imaging and its application to pulmonary functional imaging. NMR IN BIOMEDICINE 2011; 24:1343-1352. [PMID: 21538635 DOI: 10.1002/nbm.1697] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 01/21/2011] [Accepted: 01/27/2011] [Indexed: 05/30/2023]
Abstract
In the present study, a balanced steady-state free precession pulse sequence combined with compressed sensing was applied to hyperpolarized (129) Xe lung imaging in spontaneously breathing mice. With the aid of fast imaging techniques, the temporal resolution was markedly improved in the resulting images. Using these protocols and respiratory gating, (129) Xe lung images in end-inspiratory and end-expiratory phases were obtained successfully. The application of these techniques for pulmonary functional imaging made it possible to simultaneously evaluate regional ventilation and gas exchange in the same animal. A comparative study between healthy and elastase-induced mouse models of emphysema showed abnormal ventilation as well as gas exchange in elastase-treated mice.
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Affiliation(s)
- Hirohiko Imai
- Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
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30
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Ishii M, Emami K, Xin Y, Barulic A, Kotzer CJ, Logan GA, Chia E, MacDuffie-Woodburn JP, Zhu J, Pickup S, Kuzma N, Kadlecek S, Podolin PL, Rizi RR. Regional function-structure relationships in lungs of an elastase murine model of emphysema. J Appl Physiol (1985) 2011; 112:135-48. [PMID: 21940853 DOI: 10.1152/japplphysiol.01181.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Changes in lung function and structure were studied using hyperpolarized (3)He MRI in an elastase-induced murine model of emphysema. The combined analysis of the apparent diffusion coefficient (ADC) and fractional ventilation (R) were used to distinguish emphysematous changes and also to develop a model for classifying sections of the lung into diseased and normal. Twelve healthy male BALB/c mice (26 ± 2 g) were randomized into healthy and elastase-induced mice and studied ∼8-11 wk after model induction. ADC and R were measured at a submillimeter planar resolution. Chord length (L(x)) data were analyzed from histology samples from the corresponding imaged slices. Logistic regression was applied to estimate the probability that an imaged pixel came from a diseased animal, and bootstrap methods (1,000 samples) were used to compare the regression results for the morphological and imaging results. Multivariate ANOVA (MANOVA) was used to analyze transformed ADC (ADC(BC)), and R (R(BC)) data and also to control for the experiment-wide error rate. MANOVA and ANOVA showed that elastase induced a statistically measureable change in the average transformed L(x) and ADC(BC) but not in the average R(BC). Marginal mean analysis demonstrated that ADC(BC) was on average 0.19 [95% confidence interval (CI): 0.16, 0.22] higher in the emphysema group, whereas R(BC) was on average 0.05 (95% CI: 0.04, 0.06) lower. Logistic regression supported the hypothesis that ADC(BC) and R(BC), together, were better at differentiating normal from diseased tissue than either measurement alone. The odds ratios for ADC(BC) and R(BC) were 7.73 (95% CI: 5.23, 11.42) and 9.14 × 10(-5) (95% CI: 3.33 × 10(-5), 25.06 × 10(-5)), respectively. Using a 50% probability cutoff, this model classified 70.6% of pixels correctly. The sensitivity and specificity of this model at the 50% cutoff were 74.9% and 65.2%, respectively. The area under the receiver operating characteristic curve was 0.76 (95% CI: 0.74, 0.78). The regression model presented can be used to map MRI data to disease probability maps. These probability maps present a future possibility of using both measurements in a more clinically feasible method of diagnosing this disease.
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Affiliation(s)
- Masaru Ishii
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, USA
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Hamedani H, Kadlecek SJ, Emami K, Kuzma NN, Xu Y, Xin Y, Mongkolwisetwara P, Rajaei J, Barulic A, Wilson Miller G, Rossman M, Ishii M, Rizi RR. A multislice single breath-hold scheme for imaging alveolar oxygen tension in humans. Magn Reson Med 2011; 67:1332-45. [PMID: 22190347 DOI: 10.1002/mrm.23125] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 07/06/2011] [Accepted: 07/07/2011] [Indexed: 11/10/2022]
Abstract
Reliable, noninvasive, and high-resolution imaging of alveolar partial pressure of oxygen (p(A)O(2)) is a potentially valuable tool in the early diagnosis of pulmonary diseases. Several techniques have been proposed for regional measurement of p(A)O(2) based on the increased depolarization rate of hyperpolarized (3) He. In this study, we explore one such technique by applying a multislice p(A)O(2) -imaging scheme that uses interleaved-slice ordering to utilize interslice time-delays more efficiently. This approach addresses the low spatial resolution and long breath-hold requirements of earlier techniques, allowing p(A)O(2) measurements to be made over the entire human lung in 10-15 s with a typical resolution of 8.3 × 8.3 × 15.6 mm(3). PO(2) measurements in a glass syringe phantom were in agreement with independent gas analysis within 4.7 ± 4.1% (R = 0.9993). The technique is demonstrated in four human subjects (healthy nonsmoker, healthy former smoker, healthy smoker, and patient with COPD), each imaged six times on 3 different days during a 2-week span. Two independent measurements were performed in each session, consisting of 12 coronal slices. The overall p(A)O(2) mean across all subjects was 95.9 ± 12.2 Torr and correlated well with end-tidal O(2) (R = 0.805, P < 0.0001). The alveolar O(2) uptake rate was consistent with the expected range of 1-2 Torr/s. Repeatable visual features were observed in p(A)O(2) maps over different days, as were characteristic differences among the subjects and gravity-dependent effects.
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Affiliation(s)
- Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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Abstract
The continued progression of chronic lung disease despite current treatment options has led to the increasing evaluation of molecular imaging tools for diagnosis, treatment planning, drug discovery, and therapy monitoring. Concurrently the development of multimodality positron emission tomography (PET) / computed tomography (CT), single-photon emission computed tomography (SPECT)/CT, and magnetic resonance imaging (MRI)/PET scanners has opened the potential for more sophisticated imaging biomarker probes. Here we review the potential uses of multimodality imaging tools, the established uses of molecular imaging in nononcologic lung pathophysiology and drug discovery, and some of the technical challenges in multimodality molecular imaging of the lung.
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Affiliation(s)
- Delphine L Chen
- Division of Nuclear Medicine Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA
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Stephen MJ, Emami K, Woodburn JM, Chia E, Kadlecek S, Zhu J, Pickup S, Ishii M, Rizi RR, Rossman M. Quantitative assessment of lung ventilation and microstructure in an animal model of idiopathic pulmonary fibrosis using hyperpolarized gas MRI. Acad Radiol 2010; 17:1433-43. [PMID: 20934126 DOI: 10.1016/j.acra.2010.06.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 06/24/2010] [Accepted: 06/24/2010] [Indexed: 11/16/2022]
Abstract
RATIONALE AND OBJECTIVES The use of hyperpolarized (3)He magnetic resonance imaging as a quantitative lung imaging tool has progressed rapidly in the past decade, mostly in the assessment of the airway diseases chronic obstructive pulmonary disease and asthma. This technique has shown potential to assess both structural and functional information in healthy and diseased lungs. In this study, the regional measurements of structure and function were applied to a bleomycin rat model of interstitial lung disease. MATERIALS AND METHODS Male Sprague-Dawley rats (weight, 300-350 g) were administered intratracheal bleomycin. After 3 weeks, apparent diffusion coefficient and fractional ventilation were measured by (3)He magnetic resonance imaging and pulmonary function testing using a rodent-specific plethysmography chamber. Sensitized and healthy animals were then compared using threshold analysis to assess the potential sensitivity of these techniques to pulmonary abnormalities. RESULTS No significant changes were observed in total lung volume and compliance between the two groups. Airway resistance elevated and forced expiratory volume significantly declined in the 3-week bleomycin rats, and fractional ventilation was significantly decreased compared to control animals (P < .0004). The apparent diffusion coefficient of (3)He showed a smaller change but still a significant decrease in 3-week bleomycin animals (P < .05). CONCLUSIONS Preliminary results suggest that quantitative (3)He magnetic resonance imaging can be a sensitive and noninvasive tool to assess changes in an animal interstitial lung disease model. This technique may be useful for longitudinal animal studies and also in the investigation of human interstitial lung diseases.
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Affiliation(s)
- Michael J Stephen
- Department of Pulmonary and Critical Care, 834 W Gates Building, University of Pennsylvania, Philadelphia, PA 19104, USA
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Emami K, Chia E, Kadlecek S, Macduffie-Woodburn JP, Zhu J, Pickup S, Blum A, Ishii M, Rizi RR. Regional correlation of emphysematous changes in lung function and structure: a comparison between pulmonary function testing and hyperpolarized MRI metrics. J Appl Physiol (1985) 2010; 110:225-35. [PMID: 20884833 DOI: 10.1152/japplphysiol.00269.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Regional and global relationships of lung function and structure were studied using hyperpolarized ³He MRI in a rat elastase-induced model of emphysema (n = 4) and healthy controls (n = 5). Fractional ventilation (r) and apparent diffusion coefficient (ADC) of ³He were measured at a submillimeter planar resolution in ventral, middle, and dorsal slices 6 mo after model induction. Pulmonary function testing (PFT) was performed before MRI to yield forced expiratory volume in 50 ms (FEV₅₀), airway resistance (R(I)), and dynamic compliance (C(dyn)). Cutoff threshold values of ventilation and diffusion, r* and ADC*, were computed corresponding to 80% population of pixels falling above or below each threshold value, respectively. For correlation analysis, r* was compared with FEV₅₀/functional residual capacity (FRC), R(I) and C(dyn), whereas ADC* was compared with FEV₅₀/FRC, total lung capacity (TLC), and C(dyn). Regional correlation of r and ADC was evaluated by dividing each of the three lung slices into four quadrants. C(dyn) was significantly larger in elastase rats (0.92 ± 0.16 vs. 0.61 ± 0.12 ml/cmH₂O). The difference of R(I) and FEV₅₀ was insignificant between the two groups. The r* of healthy rats was significantly larger than the elastase group (0.42 ± 0.03 vs. 0.28 ± 0.06), whereas ADC* was significantly smaller in healthy animals (0.27 ± 0.04 vs. 0.36 ± 0.01 cm²/s). No systematic difference in these quantities was observed between the three lung slices. A significant 33% increase in ADC* and a significant 31% decline in r* for elastase rats was observed compared with a significant 51% increase in C(dyn) and a nonsignificant 26% decline in FEV₅₀/FRC. Correlation of imaging and PFT metrics revealed that r and ADC divide the rats into two separate clusters in the sample space.
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Affiliation(s)
- Kiarash Emami
- Department of Radiology, University of Pennsylvania, PA, USA.
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Quantitative assessment of lung using hyperpolarized magnetic resonance imaging. Ann Am Thorac Soc 2009; 6:431-8. [PMID: 19687215 DOI: 10.1513/pats.200902-008aw] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Improvements in the quantitative assessment of structure, function, and metabolic activity in the lung, combined with improvements in the spatial resolution of those assessments, enhance the diagnosis and evaluation of pulmonary disorders. Radiologic methods are among the most attractive techniques for the comprehensive assessment of the lung, as they allow quantitative assessment of this organ through measurements of a number of structural, functional, and metabolic parameters. Hyperpolarized nuclei magnetic resonance imaging (MRI) has opened up new territories for the quantitative assessment of lung function and structure with an unprecedented spatial resolution and sensitivity. This review article presents a survey of recent developments in the field of pulmonary imaging using hyperpolarized nuclei MRI for quantitative imaging of different aspects of the lung, as well as preclinical applications of these techniques to diagnose and evaluate specific pulmonary diseases. After presenting a brief overview of various hyperpolarization techniques, this survey divides the research activities of the field into four broad areas: lung microstructure, ventilation, oxygenation, and perfusion. Finally, it discusses the challenges currently faced by researchers in this field to translate this rich body of methodology into wider-scale clinical applications.
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