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Sharma M, Kirby M, McCormack DG, Parraga G. Machine Learning and CT Texture Features in Ex-smokers with no CT Evidence of Emphysema and Mildly Abnormal Diffusing Capacity. Acad Radiol 2023:S1076-6332(23)00658-X. [PMID: 38161089 DOI: 10.1016/j.acra.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/09/2023] [Accepted: 11/14/2023] [Indexed: 01/03/2024]
Abstract
RATIONALE AND OBJECTIVES Ex-smokers without spirometry or CT evidence of chronic obstructive pulmonary disease (COPD) but with mildly abnormal diffusing capacity of the lungs for carbon monoxide (DLCO) are at higher risk of developing COPD. It remains difficult to make clinical management decisions for such ex-smokers without other objective assessments consistent with COPD. Hence, our objective was to develop a machine-learning and CT texture-analysis pipeline to dichotomize ex-smokers with normal and abnormal DLCO (DLCO≥75%pred and DLCO<75%pred). MATERIALS AND METHODS In this retrospective study, 71 ex-smokers (50-85yrs) without COPD underwent spirometry, plethysmography, thoracic CT, and 3He MRI to generate ventilation defect percent (VDP) and apparent diffusion coefficients (ADC). PyRadiomics was utilized to extract 496 CT texture-features; Boruta and principal component analysis were used for feature selection and various models were investigated for classification. Machine-learning classifiers were evaluated using area under the receiver operator characteristic curve (AUC), sensitivity, specificity, and F1-measure. RESULTS Of 71 ex-smokers without COPD, 29 with mildly abnormal DLCO had significantly different MRI ADC (p < .001), residual-volume to total-lung-capacity ratio (p = .003), St. George's Respiratory Questionnaire (p = .029), and six-minute-walk distance (6MWD) (p < .001), but similar relative area of the lung < -950 Hounsfield-units (RA950) (p = .9) compared to 42 ex-smokers with normal DLCO. Logistic-regression machine-learning mixed-model trained on selected texture-features achieved the best classification accuracy of 87%. All clinical and imaging measurements were outperformed by high-high-pass filter high-gray-level-run-emphasis texture-feature (AUC=0.81), which correlated with DLCO (ρ = -0.29, p = .02), MRI ADC (ρ = 0.23, p = .048), and 6MWD (ρ = -0.25, p = .02). CONCLUSION In ex-smokers with no CT evidence of emphysema, machine-learning models exclusively trained on CT texture-features accurately classified ex-smokers with abnormal diffusing capacity, outperforming conventional quantitative CT measurements.
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Affiliation(s)
- Maksym Sharma
- Robarts Research Institute, Western University, 1151 Richmond St N, London, N6A 5B7, Canada (M.S., G.P.); Department of Medical Biophysics, Western University, London, Canada (M.S., G.P.)
| | - Miranda Kirby
- Department of Physics, Toronto Metropolitan University, Toronto, Canada (M.K.)
| | | | - Grace Parraga
- Robarts Research Institute, Western University, 1151 Richmond St N, London, N6A 5B7, Canada (M.S., G.P.); Department of Medical Biophysics, Western University, London, Canada (M.S., G.P.); Division of Respirology, Department of Medicine (D.G.M., G.P.); School of Biomedical Engineering, Western University, London, Canada (G.P.).
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2
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Enrichi C, Regazzetti M, Cieślik B, Zanetti C, D’Imperio D, Compagno E, Cacciante L, Federico S, Pregnolato G, Zitti M, Kiper P. How Lung Volume Recruitment Maneuvers Enhance Respiratory Function in Multiple Sclerosis Patients: A Quasi-Randomized Pilot Study. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:1896. [PMID: 38003947 PMCID: PMC10672745 DOI: 10.3390/medicina59111896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/22/2023] [Accepted: 10/24/2023] [Indexed: 11/26/2023]
Abstract
Background and Objectives: In patients with multiple sclerosis (MS), a decrease in muscle strength can lead to limitations in pulmonary functions, potentially causing respiratory complications. To address these challenges, the lung volume recruitment (LVR) maneuver has emerged as a potential intervention. This study sought to evaluate the impact of a four-week LVR protocol on respiratory function in secondary progressive MS patients. Materials and Methods: In a quasi-randomized pre/post-controlled trial, 24 patients with secondary progressive MS were recruited. Participants aged 20-70 years with an EDSS score of 2 to 9 were alternately allocated to intervention (n = 12) or control groups (n = 12). The intervention group underwent a 4-week respiratory rehabilitation training focused on LVR, using a standardized cough machine treatment protocol twice daily. The control group received no respiratory intervention. Outcomes measured included forced vital capacity (FVC), maximal insufflation capacity (MIC), and peak cough flow (PCF), using turbine spirometry and other associated equipment. All measurements were taken at baseline (T0) and after 4 weeks (T1) by a blinded assessor. Results: For the intervention group, the mean difference pre/post-treatment in MIC (mL) was 0.45 (SD 1.13) (p = 0.02), and in MIC (%), it was 0.13 (SD 0.24) (p = 0.03). Compared to the control group (n = 10), the between-group mean difference for MIC (mL) was 0.54 (p = 0.02), and for MIC (%), it was 0.15 (p = 0.02). Conclusions: The short-term daily LVR protocol notably improved passive lung capacity, despite minimal changes in active lung capacity or cough force. The LVR maneuver offers promise for enhancing respiratory function, especially passive lung capacity, in secondary progressive MS patients. Further research should explore optimal treatment durations and frequencies for more extensive respiratory gains.
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Affiliation(s)
- Claudia Enrichi
- Physical Medicine and Rehabilitation Unit, Azienda ULSS, 3 Serenissima, 30126 Venice, Italy; (C.E.)
| | - Martina Regazzetti
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Błażej Cieślik
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Cristiano Zanetti
- Physical Medicine and Rehabilitation Unit, Azienda ULSS, 3 Serenissima, 30126 Venice, Italy; (C.E.)
| | | | - Elisa Compagno
- CKR Centre de Kinésithérapie et Rééducation, 06000 Nice, France
| | - Luisa Cacciante
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Sara Federico
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Giorgia Pregnolato
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Mirko Zitti
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Pawel Kiper
- Healthcare Innovation Technology Lab., IRCCS San Camillo Hospital, 30126 Venice, Italy
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3
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Biederer J. MR imaging of the airways. Br J Radiol 2023; 96:20220630. [PMID: 36752590 DOI: 10.1259/bjr.20220630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
The need for airway imaging is defined by the limited sensitivity of common clinical tests like spirometry, lung diffusion (DLCO) and blood gas analysis to early changes of peripheral airways and to inhomogeneous regional distribution of lung function deficits. Therefore, X-ray and computed tomography (CT) are frequently used to complement the standard tests.As an alternative, magnetic resonance imaging (MRI) offers radiation-free lung imaging, but at lower spatial resolution. Non-contrast enhanced MRI shows healthy airways down to the first subsegmental level/4th order (CT: eighth). Bronchiectasis can be identified by wall thickening and fluid accumulation. Smaller airways become visible, when altered by peribronchiolar inflammation or mucus retention (tree-in-bud sign).The strength of MRI is functional imaging. Dynamic, time-resolved MRI directly visualizes expiratory airway collapse down to the lobar level (CT: segmental level). Obstruction of even smaller airways becomes visible as air trapping on the expiratory scans. MRI with hyperpolarized noble gases (3He, 129Xe) directly shows the large airways and peripheral lung ventilation. Dynamic contrast-enhanced MRI (DCE MRI) indirectly shows airway dysfunction as perfusion deficits resulting from hypoxic vasoconstriction of the dependent lung volumes. Further promising scientific approaches such as non-contrast enhanced, ventilation-/perfusion-weighted MRI from periodic signal changes of respiration and blood flow are in development.In summary, MRI of the lungs and airways excels with its unique combination of morphologic and functional imaging capacities for research (e.g., in chronic obstructive lung disease or asthma) as well as for clinical imaging (e.g., in cystic fibrosis).
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Affiliation(s)
- Juergen Biederer
- Christian-Albrechts-Universität zu Kiel, Faculty of Medicine, Kiel, Germany.,University of Latvia, Faculty of Medicine, Raina bulvaris, Riga, Latvia.,Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Im Neuenheimer Feld, Heidelberg, Germany.,Department of Diagnostic and interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
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4
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Shammi UA, D'Alessandro MF, Altes T, Hersman FW, Ruset IC, Mugler J, Meyer C, Mata J, Qing K, Thomen R. Comparison of Hyperpolarized 3He and 129Xe MR Imaging in Cystic Fibrosis Patients. Acad Radiol 2022; 29 Suppl 2:S82-S90. [PMID: 33487537 DOI: 10.1016/j.acra.2021.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 12/24/2020] [Accepted: 01/06/2021] [Indexed: 12/29/2022]
Abstract
PURPOSE In this study, we compared hyperpolarized 3He and 129Xe images from patients with cystic fibrosis using two commonly applied magnetic resonance sequences, standard gradient echo (GRE) and balanced steady-state free precession (TrueFISP) to quantify regional similarities and differences in signal distribution and defect analysis. MATERIALS AND METHODS Ten patients (7M/3F) with cystic fibrosis underwent hyperpolarized gas MR imaging with both 3He and 129Xe. Six had MRI with both GRE, and TrueFISP sequences and four patients had only GRE sequence but not TrueFISP. Ventilation defect percentages (VDPs) were calculated as lung voxels with <60% of the whole-lung hyperpolarized gas signal mean and was measured in all datasets. The voxel signal distributions of both 129Xe and 3He gases were visualized and compared using violin plots. VDPs of hyperpolarized 3 He and 129 Xe were compared in Bland-Altman plots; Pearson correlation coefficients were used to evaluate the relationships between inter-gas and inter-scan to assess the reproducibility. RESULTS A significant correlation was demonstrated between 129Xe VDP and 3He VDP for both GRE and TrueFISP sequences (ρ = 0.78, p<0.0004). The correlation between the GRE and TrueFISP VDP for 3He was ρ = 0.98 and was ρ = 0.91 for 129Xe. Overall, 129Xe (27.2±9.4) VDP was higher than 3He (24.3±6.9) VDP on average on cystic fibrosis patients. CONCLUSION In patients with cystic fibrosis, the selection of hyperpolarized 129Xe or 3He gas is most likely inconsequential when it comes to measure the overall lung function by VDP although 129Xe may be more sensitive to starker lung defects, particularly when using a TrueFISP sequence.
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Affiliation(s)
- Ummul Afia Shammi
- Biomedical, Biological, and Chemical Engineering, University of Missouri, Columbia, Missouri
| | | | - Talissa Altes
- Radiology, School of Medicine, University of Missouri, Columbia, Missouri
| | | | | | - John Mugler
- Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, Virginia; Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - Craig Meyer
- Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, Virginia; Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - Jamie Mata
- Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Kun Qing
- Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Robert Thomen
- Biomedical, Biological, and Chemical Engineering, University of Missouri, Columbia, Missouri; Radiology, School of Medicine, University of Missouri, Columbia, Missouri.
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5
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Kooner HK, McIntosh MJ, Desaigoudar V, Rayment JH, Eddy RL, Driehuys B, Parraga G. Pulmonary functional MRI: Detecting the structure-function pathologies that drive asthma symptoms and quality of life. Respirology 2022; 27:114-133. [PMID: 35008127 PMCID: PMC10025897 DOI: 10.1111/resp.14197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/09/2021] [Accepted: 12/12/2021] [Indexed: 12/21/2022]
Abstract
Pulmonary functional MRI (PfMRI) using inhaled hyperpolarized, radiation-free gases (such as 3 He and 129 Xe) provides a way to directly visualize inhaled gas distribution and ventilation defects (or ventilation heterogeneity) in real time with high spatial (~mm3 ) resolution. Both gases enable quantitative measurement of terminal airway morphology, while 129 Xe uniquely enables imaging the transfer of inhaled gas across the alveolar-capillary tissue barrier to the red blood cells. In patients with asthma, PfMRI abnormalities have been shown to reflect airway smooth muscle dysfunction, airway inflammation and remodelling, luminal occlusions and airway pruning. The method is rapid (8-15 s), cost-effective (~$300/scan) and very well tolerated in patients, even in those who are very young or very ill, because unlike computed tomography (CT), positron emission tomography and single-photon emission CT, there is no ionizing radiation and the examination takes only a few seconds. However, PfMRI is not without limitations, which include the requirement of complex image analysis, specialized equipment and additional training and quality control. We provide an overview of the three main applications of hyperpolarized noble gas MRI in asthma research including: (1) inhaled gas distribution or ventilation imaging, (2) alveolar microstructure and finally (3) gas transfer into the alveolar-capillary tissue space and from the tissue barrier into red blood cells in the pulmonary microvasculature. We highlight the evidence that supports a deeper understanding of the mechanisms of asthma worsening over time and the pathologies responsible for symptoms and disease control. We conclude with a summary of approaches that have the potential for integration into clinical workflows and that may be used to guide personalized treatment planning.
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Affiliation(s)
- Harkiran K Kooner
- Robarts Research Institute, Western University, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Marrissa J McIntosh
- Robarts Research Institute, Western University, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Vedanth Desaigoudar
- Robarts Research Institute, Western University, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Jonathan H Rayment
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rachel L Eddy
- Centre of Heart Lung Innovation, Division of Respiratory Medicine, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Centre, Durham, North Carolina, USA
| | - Grace Parraga
- Robarts Research Institute, Western University, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- Division of Respirology, Department of Medicine, Western University, London, Ontario, Canada
- School of Biomedical Engineering, Western University, London, Ontario, Canada
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6
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Buhl N. Analytic determination of lung microgeometry with gas diffusion magnetic resonance. Phys Rev E 2021; 103:052406. [PMID: 34134344 DOI: 10.1103/physreve.103.052406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 03/06/2021] [Indexed: 11/07/2022]
Abstract
Through inhalation of, e.g., hyperpolarized ^{3}He, it is possible to acquire gas diffusion magnetic resonance measurements that depend on the local geometry in the vast network of microscopic airways that form the respiratory zone of the human lung. Here, we demonstrate that this can be used to determine the dimensions (length and radius) of these airways noninvasively. Specifically, the above technique allows measurement of the weighted time-dependent diffusion coefficient (also called the apparent diffusion coefficient), which we here derive in analytic form using symmetries in the airway network. Agreement with experiment is found for the full span of published hyperpolarized ^{3}He diffusion magnetic resonance measurements (diffusion times from milliseconds to seconds) and published invasive airway dimension measurements.
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Affiliation(s)
- Niels Buhl
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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7
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Tanaka Y, Ohno Y, Hanamatsu S, Obama Y, Ueda T, Ikeda H, Iwase A, Fukuba T, Hattori H, Murayama K, Yoshikawa T, Takenaka D, Koyama H, Toyama H. State-of-the-art MR Imaging for Thoracic Diseases. Magn Reson Med Sci 2021; 21:212-234. [PMID: 33952785 PMCID: PMC9199970 DOI: 10.2463/mrms.rev.2020-0184] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Since thoracic MR imaging was first used in a clinical setting, it has been suggested that MR imaging has limited clinical utility for thoracic diseases, especially lung diseases, in comparison with x-ray CT and positron emission tomography (PET)/CT. However, in many countries and states and for specific indications, MR imaging has recently become practicable. In addition, recently developed pulmonary MR imaging with ultra-short TE (UTE) and zero TE (ZTE) has enhanced the utility of MR imaging for thoracic diseases in routine clinical practice. Furthermore, MR imaging has been introduced as being capable of assessing pulmonary function. It should be borne in mind, however, that these applications have so far been academically and clinically used only for healthy volunteers, but not for patients with various pulmonary diseases in Japan or other countries. In 2020, the Fleischner Society published a new report, which provides consensus expert opinions regarding appropriate clinical indications of pulmonary MR imaging for not only oncologic but also pulmonary diseases. This review article presents a brief history of MR imaging for thoracic diseases regarding its technical aspects and major clinical indications in Japan 1) in terms of what is currently available, 2) promising but requiring further validation or evaluation, and 3) developments warranting research investigations in preclinical or patient studies. State-of-the-art MR imaging can non-invasively visualize lung structural and functional abnormalities without ionizing radiation and thus provide an alternative to CT. MR imaging is considered as a tool for providing unique information. Moreover, prospective, randomized, and multi-center trials should be conducted to directly compare MR imaging with conventional methods to determine whether the former has equal or superior clinical relevance. The results of these trials together with continued improvements are expected to update or modify recommendations for the use of MRI in near future.
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Affiliation(s)
- Yumi Tanaka
- Department of Radiology, Fujita Health University School of Medicine
| | - Yoshiharu Ohno
- Department of Radiology, Fujita Health University School of Medicine.,Joint Research Laboratory of Advanced Medical Imaging, Fujita Health University School of Medicine
| | - Satomu Hanamatsu
- Department of Radiology, Fujita Health University School of Medicine
| | - Yuki Obama
- Department of Radiology, Fujita Health University School of Medicine
| | - Takahiro Ueda
- Department of Radiology, Fujita Health University School of Medicine
| | - Hirotaka Ikeda
- Department of Radiology, Fujita Health University School of Medicine
| | - Akiyoshi Iwase
- Department of Radiology, Fujita Health University Hospital
| | - Takashi Fukuba
- Department of Radiology, Fujita Health University Hospital
| | - Hidekazu Hattori
- Department of Radiology, Fujita Health University School of Medicine
| | - Kazuhiro Murayama
- Joint Research Laboratory of Advanced Medical Imaging, Fujita Health University School of Medicine
| | | | | | | | - Hiroshi Toyama
- Department of Radiology, Fujita Health University School of Medicine
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8
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Airspace Dimension Assessment (AiDA) by inhaled nanoparticles: benchmarking with hyperpolarised 129Xe diffusion-weighted lung MRI. Sci Rep 2021; 11:4721. [PMID: 33633165 PMCID: PMC7907057 DOI: 10.1038/s41598-021-83975-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/10/2021] [Indexed: 11/26/2022] Open
Abstract
Enlargements of distal airspaces can indicate pathological changes in the lung, but accessible and precise techniques able to measure these regions are lacking. Airspace Dimension Assessment with inhaled nanoparticles (AiDA) is a new method developed for in vivo measurement of distal airspace dimensions. The aim of this study was to benchmark the AiDA method against quantitative measurements of distal airspaces from hyperpolarised 129Xe diffusion-weighted (DW)-lung magnetic resonance imaging (MRI). AiDA and 129Xe DW-MRI measurements were performed in 23 healthy volunteers who spanned an age range of 23–70 years. The relationship between the 129Xe DW-MRI and AiDA metrics was tested using Spearman’s rank correlation coefficient. Significant correlations were observed between AiDA distal airspace radius (rAiDA) and mean 129Xe apparent diffusion coefficient (ADC) (p < 0.005), distributed diffusivity coefficient (DDC) (p < 0.001) and distal airspace dimension (LmD) (p < 0.001). A mean bias of − 1.2 µm towards rAiDA was observed between 129Xe LmD and rAiDA, indicating that rAiDA is a measure of distal airspace dimension. The AiDA R0 intercept correlated with MRI 129Xe α (p = 0.02), a marker of distal airspace heterogeneity. This study demonstrates that AiDA has potential to characterize the distal airspace microstructures and may serve as an alternative method for clinical examination of the lungs.
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Tafti S, Garrison WJ, Mugler JP, Shim YM, Altes TA, Mata JF, de Lange EE, Cates GD, Ropp AM, Wang C, Miller GW. Emphysema Index Based on Hyperpolarized 3He or 129Xe Diffusion MRI: Performance and Comparison with Quantitative CT and Pulmonary Function Tests. Radiology 2020; 297:201-210. [PMID: 32779976 DOI: 10.1148/radiol.2020192804] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Background Apparent diffusion coefficient (ADC) maps of inhaled hyperpolarized gases have shown promise in the characterization of emphysema in patients with chronic obstructive pulmonary disease (COPD), yet an easily interpreted quantitative metric beyond mean and standard deviation has not been established. Purpose To introduce a quantitative framework with which to characterize emphysema burden based on hyperpolarized helium 3 (3He) and xenon 129 (129Xe) ADC maps and compare its diagnostic performance with CT-based emphysema metrics and pulmonary function tests (PFTs). Materials and Methods Twenty-seven patients with mild, moderate, or severe COPD and 13 age-matched healthy control subjects participated in this retrospective study. Participants underwent CT and multiple b value diffusion-weighted 3He and 129Xe MRI examinations and standard PFTs between August 2014 and November 2017. ADC-based emphysema index was computed separately for each gas and b value as the fraction of lung voxels with ADC values greater than in the healthy group 99th percentile. The resulting values were compared with quantitative CT results (relative lung area <-950 HU) as the reference standard. Diagnostic performance metrics included area under the receiver operating characteristic curve (AUC). Spearman rank correlations and Wilcoxon rank sum tests were performed between ADC-, CT-, and PFT-based metrics, and intraclass correlation was performed between repeated measurements. Results Thirty-six participants were evaluated (mean age, 60 years ± 6 [standard deviation]; 20 women). ADC-based emphysema index was highly repeatable (intraclass correlation coefficient > 0.99) and strongly correlated with quantitative CT (r = 0.86, P < .001 for 3He; r = 0.85, P < .001 for 129Xe) with high AUC (≥0.93; 95% confidence interval [CI]: 0.85, 1.00). ADC emphysema indices were also correlated with percentage of predicted diffusing capacity of lung for carbon monoxide (r = -0.81, P < .001 for 3He; r = -0.80, P < .001 for 129Xe) and percentage of predicted residual lung volume divided by total lung capacity (r = 0.65, P < .001 for 3He; r = 0.61, P < .001 for 129Xe). Conclusion Emphysema index based on hyperpolarized helium 3 or xenon 129 diffusion MRI provides a repeatable measure of emphysema burden, independent of gas or b value, with similar diagnostic performance as quantitative CT or pulmonary function metrics. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Schiebler and Fain in this issue.
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Affiliation(s)
- Sina Tafti
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - William J Garrison
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - John P Mugler
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Y Michael Shim
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Talissa A Altes
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Jaime F Mata
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Eduard E de Lange
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Gordon D Cates
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Alan M Ropp
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - Chengbo Wang
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
| | - G Wilson Miller
- From the Departments of Physics (S.T., G.D.C.), Biomedical Engineering (W.J.G., J.P.M., G.W.M.), Radiology and Medical Imaging (J.P.M., J.F.M., E.E.d.L., A.M.R., G.W.M.), and Medicine (Y.M.S.), University of Virginia, Box 801339, Charlottesville, VA 22908; Department of Radiology, University of Missouri, Columbia, Mo (T.A.A.); and Department of Science and Engineering, University of Nottingham, Ningbo, China (C.W.)
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10
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Abstract
This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.
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Affiliation(s)
- David A Kaminsky
- University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - David G Chapman
- University of Technology Sydney, Sydney, New South Wales, Australia
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11
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Zhang H, Xie J, Xiao S, Zhao X, Zhang M, Shi L, Wang K, Wu G, Sun X, Ye C, Zhou X. Lung morphometry using hyperpolarized
129
Xe multi‐
b
diffusion
MRI
with compressed sensing in healthy subjects and patients with
COPD. Med Phys 2018; 45:3097-3108. [DOI: 10.1002/mp.12944] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 12/11/2022] Open
Affiliation(s)
- Huiting Zhang
- School of Physics Huazhong University of Science and Technology Wuhan 430074China
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Junshuai Xie
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Sa Xiao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Xiuchao Zhao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Ming Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Lei Shi
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Ke Wang
- Department of Magnetic Resonance Imaging Zhongnan Hospital of Wuhan University Wuhan 430071 China
| | - Guangyao Wu
- Department of Magnetic Resonance Imaging Zhongnan Hospital of Wuhan University Wuhan 430071 China
| | - Xianping Sun
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Chaohui Ye
- School of Physics Huazhong University of Science and Technology Wuhan 430074China
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
| | - Xin Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in Wuhan Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071China
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12
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Wang K, Pan T, Yang H, Ruan W, Zhong J, Wu G, Zhou X. Assessment of pulmonary microstructural changes by hyperpolarized 129Xe diffusion-weighted imaging in an elastase-instilled rat model of emphysema. J Thorac Dis 2017; 9:2572-2578. [PMID: 28932564 DOI: 10.21037/jtd.2017.08.39] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The purpose of this study was to explore the feasibility of hyperpolarized 129Xe diffusion-weighted imaging (DWI) for the evaluation of pulmonary microstructural changes in the presence of pancreatic porcine elastase (PPE)-induced pulmonary emphysema rat model. METHODS Sixteen male Sprague-Dawley (SD) rats were randomly divided into two groups, the emphysema model group and control group. Experimental emphysematous models were made by instilling elastase into rat lungs of model group, the control group were instilled with isodose saline. Hyperpolarized 129Xe magnetic resonance imaging (MRI) and histology were performed in all 16 rats after 30 days. DWIs were performed on a Bruker 7.0 T micro MRI, and the apparent diffusion coefficients (ADCs) were measured in all rats. Mean linear intercepts (MLIs) of pulmonary alveoli were measured on histology. The statistical analyses were performed about the correlation between the mean ADC of hyperpolarized 129Xe in the whole lung and MLI of pulmonary histology metric. RESULTS The pulmonary emphysematous model was successfully confirmed by the histology and all scans were also successful. The ADC value of 129Xe in the model group (0.0313±0.0005 cm2/s) was significantly increased compared with that of the control group (0.0288±0.0007 cm2/s, P<0.0001). Morphological differences such as MLI of pulmonary alveoli were observed between the two groups, the MLI of pulmonary alveoli in model group significantly increased (91±5 µm) than that of control group (50±3 µm, P<0.0001). Furthermore, the ADCs was moderately correlated with MLIs (r=0.724, P<0.01). CONCLUSIONS These results indicate that 129Xe ADC value can quantitatively reflect the alveolar space enlargement and it is a promising biomarker for the detection of pulmonary emphysema.
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Affiliation(s)
- Ke Wang
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Ting Pan
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Hao Yang
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Weiwei Ruan
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Jianping Zhong
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Guangyao Wu
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Xin Zhou
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
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13
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Trivedi A, Hall C, Hoffman EA, Woods JC, Gierada DS, Castro M. Using imaging as a biomarker for asthma. J Allergy Clin Immunol 2017; 139:1-10. [PMID: 28065276 DOI: 10.1016/j.jaci.2016.11.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/16/2016] [Accepted: 11/17/2016] [Indexed: 12/31/2022]
Abstract
There have been significant advancements in the various imaging techniques being used for the evaluation of asthmatic patients, both from a clinical and research perspective. Imaging characteristics can be used to identify specific asthmatic phenotypes and provide a more detailed understanding of endotypes contributing to the pathophysiology of the disease. Computed tomography, magnetic resonance imaging, and positron emission tomography can be used to assess pulmonary structure and function. It has been shown that specific airway and lung density measurements using computed tomography correlate with clinical parameters, including severity of disease and pathology, but also provide unique phenotypes. Hyperpolarized 129Xe and 3He are gases used as contrast media for magnetic resonance imaging that provide measurement of distal lung ventilation reflecting small-airway disease. Positron emission tomography can be useful to identify and target lung inflammation in asthmatic patients. Furthermore, imaging techniques can serve as a potential biomarker and be used to assess response to therapies, including newer biological treatments and bronchial thermoplasty.
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Affiliation(s)
- Abhaya Trivedi
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, Mo
| | - Chase Hall
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, Mo
| | - Eric A Hoffman
- Department of Biomedical Engineering, Department of Radiology, University of Iowa College of Medicine, Iowa City, Iowa
| | - Jason C Woods
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - David S Gierada
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, Mo
| | - Mario Castro
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, Mo.
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14
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Hyperpolarized Gas Magnetic Resonance Lung Imaging in Children and Young Adults. J Thorac Imaging 2017; 31:285-95. [PMID: 27428024 DOI: 10.1097/rti.0000000000000218] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The assessment of early pulmonary disease and its severity can be difficult in young children, as procedures such as spirometry cannot be performed on them. Computed tomography provides detailed structural images of the pulmonary parenchyma, but its major drawback is that the patient is exposed to ionizing radiation. In this context, magnetic resonance imaging (MRI) is a promising technique for the evaluation of pediatric lung disease, especially when serial imaging is needed. Traditionally, MRI played a small role in evaluating the pulmonary parenchyma. Because of its low proton density, the lungs display low signal intensity on conventional proton-based MRI. Hyperpolarized (HP) gases are inhaled contrast agents with an excellent safety profile and provide high signal within the lung, allowing for high temporal and spatial resolution imaging of the lung airspaces. Besides morphologic information, HP MR images also offer valuable information about pulmonary physiology. HP gas MRI has already made new contributions to the understanding of pediatric lung diseases and may become a clinically useful tool. In this article, we discuss the HP gas MRI technique, special considerations that need to be made when imaging children, and the role of MRI in 2 of the most common chronic pediatric lung diseases, asthma and cystic fibrosis. We also will discuss how HP gas MRI may be used to evaluate normal lung growth and development and the alterations occurring in chronic lung disease of prematurity and in patients with a congenital diaphragmatic hernia.
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15
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Adamson EB, Ludwig KD, Mummy DG, Fain SB. Magnetic resonance imaging with hyperpolarized agents: methods and applications. Phys Med Biol 2017; 62:R81-R123. [PMID: 28384123 DOI: 10.1088/1361-6560/aa6be8] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In the past decade, hyperpolarized (HP) contrast agents have been under active development for MRI applications to address the twin challenges of functional and quantitative imaging. Both HP helium (3He) and xenon (129Xe) gases have reached the stage where they are under study in clinical research. HP 129Xe, in particular, is poised for larger scale clinical research to investigate asthma, chronic obstructive pulmonary disease, and fibrotic lung diseases. With advances in polarizer technology and unique capabilities for imaging of 129Xe gas exchange into lung tissue and blood, HP 129Xe MRI is attracting new attention. In parallel, HP 13C and 15N MRI methods have steadily advanced in a wide range of pre-clinical research applications for imaging metabolism in various cancers and cardiac disease. The HP [1-13C] pyruvate MRI technique, in particular, has undergone phase I trials in prostate cancer and is poised for investigational new drug trials at multiple institutions in cancer and cardiac applications. This review treats the methodology behind both HP gases and HP 13C and 15N liquid state agents. Gas and liquid phase HP agents share similar technologies for achieving non-equilibrium polarization outside the field of the MRI scanner, strategies for image data acquisition, and translational challenges in moving from pre-clinical to clinical research. To cover the wide array of methods and applications, this review is organized by numerical section into (1) a brief introduction, (2) the physical and biological properties of the most common polarized agents with a brief summary of applications and methods of polarization, (3) methods for image acquisition and reconstruction specific to improving data acquisition efficiency for HP MRI, (4) the main physical properties that enable unique measures of physiology or metabolic pathways, followed by a more detailed review of the literature describing the use of HP agents to study: (5) metabolic pathways in cancer and cardiac disease and (6) lung function in both pre-clinical and clinical research studies, concluding with (7) some future directions and challenges, and (8) an overall summary.
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Affiliation(s)
- Erin B Adamson
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States of America
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16
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Yablonskiy DA, Sukstanskii AL, Quirk JD. Diffusion lung imaging with hyperpolarized gas MRI. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3448. [PMID: 26676342 PMCID: PMC4911335 DOI: 10.1002/nbm.3448] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/20/2015] [Accepted: 10/22/2015] [Indexed: 05/28/2023]
Abstract
Lung imaging using conventional 1 H MRI presents great challenges because of the low density of lung tissue, lung motion and very fast lung tissue transverse relaxation (typical T2 * is about 1-2 ms). MRI with hyperpolarized gases (3 He and 129 Xe) provides a valuable alternative because of the very strong signal originating from inhaled gas residing in the lung airspaces and relatively slow gas T2 * relaxation (typical T2 * is about 20-30 ms). However, in vivo human experiments should be performed very rapidly - usually during a single breath-hold. In this review, we describe the recent developments in diffusion lung MRI with hyperpolarized gases. We show that a combination of the results of modeling of gas diffusion in lung airspaces and diffusion measurements with variable diffusion-sensitizing gradients allows the extraction of quantitative information on the lung microstructure at the alveolar level. From an MRI scan of less than 15 s, this approach, called in vivo lung morphometry, allows the provision of quantitative values and spatial distributions of the same physiological parameters as measured by means of 'standard' invasive stereology (mean linear intercept, surface-to-volume ratio, density of alveoli, etc.). In addition, the approach makes it possible to evaluate some advanced Weibel parameters characterizing lung microstructure: average radii of alveolar sacs and ducts, as well as the depth of their alveolar sleeves. Such measurements, providing in vivo information on the integrity of pulmonary acinar airways and their changes in different diseases, are of great importance and interest to a broad range of physiologists and clinicians. We also discuss a new type of experiment based on the in vivo lung morphometry technique combined with quantitative computed tomography measurements, as well as with gradient echo MRI measurements of hyperpolarized gas transverse relaxation in the lung airspaces. Such experiments provide additional information on the blood vessel volume fraction, specific gas volume and length of the acinar airways, and allow the evaluation of lung parenchymal and non-parenchymal tissue. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
| | | | - James D Quirk
- Department of Radiology, Washington University, St. Louis, MO, USA
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17
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Sheikh K, Guo F, Capaldi DPI, Ouriadov A, Eddy RL, Svenningsen S, Parraga G. Ultrashort echo time MRI biomarkers of asthma. J Magn Reson Imaging 2016; 45:1204-1215. [PMID: 27731948 DOI: 10.1002/jmri.25503] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/20/2016] [Indexed: 01/08/2023] Open
Abstract
PURPOSE To develop and assess ultrashort echo-time (UTE) magnetic resonance imaging (MRI) biomarkers of lung function in asthma patients. MATERIALS AND METHODS Thirty participants including 13 healthy volunteers and 17 asthmatics provided written informed consent to UTE and pulmonary function tests in addition to hyperpolarized-noble-gas 3T MRI and computed tomography (CT) for asthmatics only. The difference in MRI signal-intensity (SI) across four lung volumes (full-expiration, functional-residual-capacity [FRC], FRC+1L, and full-inspiration) was determined on a voxel-by-voxel basis to generate dynamic proton-density (DPD) maps. MRI ventilation-defect-percent (VDP), UTE SI, and DPD values as well as CT radiodensity were determined for whole lung and individual lobes. RESULTS Mean SI at full-expiration (P < 0.01), FRC (P < 0.05), and DPD (P < 0.01) were greater in healthy volunteers compared to asthmatics. In asthmatics, UTE SI at full-expiration and DPD were correlated with FEV1 /FVC (SI r = 0.73/P = 0.002; DPD r = 0.75/P = 0.003), RV/TLC (SI r = -0.57/P = 0.02), or RV (DPD r = -0.62/P = 0.02), CT radiodensity (SI r = 0.83/P = 0.006; DPD r = 0.71/P = 0.01), and lobar VDP (SI rs = -0.33/P = 0.02; DPD rs = -0.47/P = 0.01). CONCLUSION In patients with asthma, UTE SI and dynamic proton-density were related to pulmonary function measurements, whole lung and lobar VDP, as well as CT radiodensity. Thus, UTE MRI biomarkers may reflect ventilation heterogeneity and/or gas-trapping in asthmatics using conventional equipment, making this approach potentially amenable for clinical use. LEVEL OF EVIDENCE 2 J. Magn. Reson. Imaging 2017;45:1204-1215.
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Affiliation(s)
- Khadija Sheikh
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Fumin Guo
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Graduate Program in Biomedical Engineering, The University of Western Ontario, London, Canada
| | - Dante P I Capaldi
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Alexei Ouriadov
- Robarts Research Institute, The University of Western Ontario, London, Canada
| | - Rachel L Eddy
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Sarah Svenningsen
- Robarts Research Institute, The University of Western Ontario, London, Canada
| | - Grace Parraga
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada.,Graduate Program in Biomedical Engineering, The University of Western Ontario, London, Canada
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18
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Hoffman EA, Lynch DA, Barr RG, van Beek EJR, Parraga G. Pulmonary CT and MRI phenotypes that help explain chronic pulmonary obstruction disease pathophysiology and outcomes. J Magn Reson Imaging 2016; 43:544-57. [PMID: 26199216 PMCID: PMC5207206 DOI: 10.1002/jmri.25010] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/01/2015] [Indexed: 12/12/2022] Open
Abstract
Pulmonary x-ray computed tomographic (CT) and magnetic resonance imaging (MRI) research and development has been motivated, in part, by the quest to subphenotype common chronic lung diseases such as chronic obstructive pulmonary disease (COPD). For thoracic CT and MRI, the main COPD research tools, disease biomarkers are being validated that go beyond anatomy and structure to include pulmonary functional measurements such as regional ventilation, perfusion, and inflammation. In addition, there has also been a drive to improve spatial and contrast resolution while at the same time reducing or eliminating radiation exposure. Therefore, this review focuses on our evolving understanding of patient-relevant and clinically important COPD endpoints and how current and emerging MRI and CT tools and measurements may be exploited for their identification, quantification, and utilization. Since reviews of the imaging physics of pulmonary CT and MRI and reviews of other COPD imaging methods were previously published and well-summarized, we focus on the current clinical challenges in COPD and the potential of newly emerging MR and CT imaging measurements to address them. Here we summarize MRI and CT imaging methods and their clinical translation for generating reproducible and sensitive measurements of COPD related to pulmonary ventilation and perfusion as well as parenchyma morphology. The key clinical problems in COPD provide an important framework in which pulmonary imaging needs to rapidly move in order to address the staggering burden, costs, as well as the mortality and morbidity associated with COPD.
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Affiliation(s)
- Eric A Hoffman
- Department of Radiology, University of Iowa, Iowa City, Iowa, USA
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA
| | - David A Lynch
- Department of Radiology, National Jewish Health Center, Denver, Colorado, USA
| | - R Graham Barr
- Division of General Medicine, Division of Pulmonary, Allergy and Critical Care, Department of Medicine, Columbia University Medical Center, New York, New York, USA
- Department of Epidemiology, Columbia University Medical Center, New York, New York, USA
| | - Edwin J R van Beek
- Clinical Research Imaging Centre, Queen's Medical Research Institute, University of Edinburgh, Scotland, UK
| | - Grace Parraga
- Robarts Research Institute, University of Western Ontario, London, Canada
- Department of Medical Biophysics, University of Western Ontario, London, Canada
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19
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Baldi S, Hartley R, Brightling C, Gupta S. Asthma. IMAGING 2016. [DOI: 10.1183/2312508x.10002815] [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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20
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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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21
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Kruger SJ, Nagle SK, Couch MJ, Ohno Y, Albert M, Fain SB. Functional imaging of the lungs with gas agents. J Magn Reson Imaging 2016; 43:295-315. [PMID: 26218920 PMCID: PMC4733870 DOI: 10.1002/jmri.25002] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/26/2015] [Indexed: 12/22/2022] Open
Abstract
This review focuses on the state-of-the-art of the three major classes of gas contrast agents used in magnetic resonance imaging (MRI)-hyperpolarized (HP) gas, molecular oxygen, and fluorinated gas--and their application to clinical pulmonary research. During the past several years there has been accelerated development of pulmonary MRI. This has been driven in part by concerns regarding ionizing radiation using multidetector computed tomography (CT). However, MRI also offers capabilities for fast multispectral and functional imaging using gas agents that are not technically feasible with CT. Recent improvements in gradient performance and radial acquisition methods using ultrashort echo time (UTE) have contributed to advances in these functional pulmonary MRI techniques. The relative strengths and weaknesses of the main functional imaging methods and gas agents are compared and applications to measures of ventilation, diffusion, and gas exchange are presented. Functional lung MRI methods using these gas agents are improving our understanding of a wide range of chronic lung diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis in both adults and children.
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Affiliation(s)
- Stanley J. Kruger
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
| | - Scott K. Nagle
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Pediatrics, University of Wisconsin – Madison, WI, U.S.A
| | - Marcus J. Couch
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Biotechnology Program, Lakehead University, Thunder Bay, ON, Canada
| | - Yoshiharu Ohno
- Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Mitchell Albert
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Department of Chemistry, Lakehead University, Thunder Bay, ON, Canada
| | - Sean B. Fain
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Biomedical Engineering, University of Wisconsin – Madison, WI, U.S.A
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22
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Yablonskiy DA, Sukstanskii AL, Quirk JD, Woods JC, Conradi MS. Probing lung microstructure with hyperpolarized noble gas diffusion MRI: theoretical models and experimental results. Magn Reson Med 2016; 71:486-505. [PMID: 23554008 DOI: 10.1002/mrm.24729] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The introduction of hyperpolarized gases ((3)He and (129)Xe) has opened the door to applications for which gaseous agents are uniquely suited-lung MRI. One of the pulmonary applications, diffusion MRI, relies on measuring Brownian motion of inhaled hyperpolarized gas atoms diffusing in lung airspaces. In this article we provide an overview of the theoretical ideas behind hyperpolarized gas diffusion MRI and the results obtained over the decade-long research. We describe a simple technique based on measuring gas apparent diffusion coefficient (ADC) and an advanced technique, in vivo lung morphometry, that quantifies lung microstructure both in terms of Weibel parameters (acinar airways radii and alveolar depth) and standard metrics (mean linear intercept, surface-to-volume ratio, and alveolar density) that are widely used by lung researchers but were previously available only from invasive lung biopsy. This technique has the ability to provide unique three-dimensional tomographic information on lung microstructure from a less than 15 s MRI scan with results that are in good agreement with direct histological measurements. These safe and sensitive diffusion measurements improve our understanding of lung structure and functioning in health and disease, providing a platform for monitoring the efficacy of therapeutic interventions in clinical trials.
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23
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Walkup LL, Woods JC. Advances in Imaging Cystic Fibrosis Lung Disease. PEDIATRIC ALLERGY IMMUNOLOGY AND PULMONOLOGY 2015; 28:220-229. [DOI: 10.1089/ped.2015.0588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Laura L. Walkup
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Jason C. Woods
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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Zhang WJ, Niven RM, Young SS, Liu YZ, Parker GJM, Naish JH. T1-weighted Dynamic Contrast-enhanced MR Imaging of the Lung in Asthma: Semiquantitative Analysis for the Assessment of Contrast Agent Kinetic Characteristics. Radiology 2015; 278:906-16. [PMID: 26491908 DOI: 10.1148/radiol.2015141876] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
PURPOSE To evaluate the contrast agent kinetics of dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging in healthy lungs and asthmatic lungs by using non-model-based semiquantitative parameters and to explore the relationships with pulmonary function testing and eosinophil level. MATERIALS AND METHODS The study was approved by the National Research Ethical Committee (reference no. 11/NW/0387), and written informed consent was obtained from all individuals. Ten healthy subjects and 30 patients with asthma underwent pulmonary function tests, blood and sputum eosinophil counts, and 1.5-T DCE MR imaging within 7 days. Semiquantitative parameters of contrast agent kinetics were calculated from the relative signal intensity-time course curves on a pixel-by-pixel basis and were summarized by using whole-lung median values. The distribution heterogeneity was assessed by using the regional coefficient of variation. DCE MR imaging readouts were compared between groups by using one-way analysis of variance, and the relationships with pulmonary function testing and eosinophil counts were assessed by using Pearson correlation analysis. RESULTS Asthmatic patients showed significantly lower peak enhancement (P < .001) and initial areas under the relative signal intensity curve in the first 60 seconds (P = .002) and significantly reduced late-phase washout slope (P = .002) when compared with healthy control subjects. The distribution heterogeneity of bolus arrival time (P = .029), time to peak (P = .008), upslope of the first-pass peak (P = .011), and late-phase washout slope (P = .032), estimated by using the median coefficient of variation, were significantly higher in asthmatic patients than in healthy control subjects. These imaging readouts also showed significant linear correlations with measurements of pulmonary function testing but not with eosinophil level in patients with asthma. CONCLUSION The contrast agent kinetic characteristics of T1-weighted DCE MR images of asthmatic lungs are different from those of healthy lungs and are related to measurements of pulmonary function testing but not to eosinophil level.
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Affiliation(s)
- Wei-Juan Zhang
- From the Centre for Imaging Sciences (W.J.Z., G.J.M.P., J.H.N.) and Biomedical Imaging Institute (W.J.Z., G.J.M.P., J.H.N.), the University of Manchester, Oxford Rd, Manchester M13 9PT, England; North West Lung Research Centre, University Hospital of South Manchester, Manchester, England (R.M.N.); Personalised Healthcare and Biomarkers, AstraZeneca R&D, Macclesfield, England (S.S.Y., Y.Z.L.); and Bioxydyn Limited, Manchester, England (G.J.M.P.)
| | - Robert M Niven
- From the Centre for Imaging Sciences (W.J.Z., G.J.M.P., J.H.N.) and Biomedical Imaging Institute (W.J.Z., G.J.M.P., J.H.N.), the University of Manchester, Oxford Rd, Manchester M13 9PT, England; North West Lung Research Centre, University Hospital of South Manchester, Manchester, England (R.M.N.); Personalised Healthcare and Biomarkers, AstraZeneca R&D, Macclesfield, England (S.S.Y., Y.Z.L.); and Bioxydyn Limited, Manchester, England (G.J.M.P.)
| | - Simon S Young
- From the Centre for Imaging Sciences (W.J.Z., G.J.M.P., J.H.N.) and Biomedical Imaging Institute (W.J.Z., G.J.M.P., J.H.N.), the University of Manchester, Oxford Rd, Manchester M13 9PT, England; North West Lung Research Centre, University Hospital of South Manchester, Manchester, England (R.M.N.); Personalised Healthcare and Biomarkers, AstraZeneca R&D, Macclesfield, England (S.S.Y., Y.Z.L.); and Bioxydyn Limited, Manchester, England (G.J.M.P.)
| | - Yu-Zhen Liu
- From the Centre for Imaging Sciences (W.J.Z., G.J.M.P., J.H.N.) and Biomedical Imaging Institute (W.J.Z., G.J.M.P., J.H.N.), the University of Manchester, Oxford Rd, Manchester M13 9PT, England; North West Lung Research Centre, University Hospital of South Manchester, Manchester, England (R.M.N.); Personalised Healthcare and Biomarkers, AstraZeneca R&D, Macclesfield, England (S.S.Y., Y.Z.L.); and Bioxydyn Limited, Manchester, England (G.J.M.P.)
| | - Geoffrey J M Parker
- From the Centre for Imaging Sciences (W.J.Z., G.J.M.P., J.H.N.) and Biomedical Imaging Institute (W.J.Z., G.J.M.P., J.H.N.), the University of Manchester, Oxford Rd, Manchester M13 9PT, England; North West Lung Research Centre, University Hospital of South Manchester, Manchester, England (R.M.N.); Personalised Healthcare and Biomarkers, AstraZeneca R&D, Macclesfield, England (S.S.Y., Y.Z.L.); and Bioxydyn Limited, Manchester, England (G.J.M.P.)
| | - Josephine H Naish
- From the Centre for Imaging Sciences (W.J.Z., G.J.M.P., J.H.N.) and Biomedical Imaging Institute (W.J.Z., G.J.M.P., J.H.N.), the University of Manchester, Oxford Rd, Manchester M13 9PT, England; North West Lung Research Centre, University Hospital of South Manchester, Manchester, England (R.M.N.); Personalised Healthcare and Biomarkers, AstraZeneca R&D, Macclesfield, England (S.S.Y., Y.Z.L.); and Bioxydyn Limited, Manchester, England (G.J.M.P.)
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Hartley R, Baldi S, Brightling C, Gupta S. Novel imaging approaches in adult asthma and their clinical potential. Expert Rev Clin Immunol 2015; 11:1147-62. [PMID: 26289375 DOI: 10.1586/1744666x.2015.1072049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Currently, imaging in asthma is confined to chest radiography and CT. The emergence of new imaging techniques and tremendous improvement of existing imaging methods, primarily due to technological advancement, has completely changed its research and clinical prospects. In research, imaging in asthma is now being employed to provide quantitative assessment of morphology, function and pathogenic processes at the molecular level. The unique ability of imaging for non-invasive, repeated, quantitative, and in vivo assessment of structure and function in asthma could lead to identification of 'imaging biomarkers' with potential as outcome measures in future clinical trials. Emerging imaging techniques and their utility in the research and clinical setting is discussed in this review.
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Affiliation(s)
- Ruth Hartley
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK
| | - Simonetta Baldi
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK
| | - Chris Brightling
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK
| | - Sumit Gupta
- a 1 Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, LE3 9QP, UK.,b 2 Radiology Department, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Leicester, LE3 9QP, UK
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Characterization of acinar airspace involvement in asthmatic patients by using inert gas washout and hyperpolarized (3)helium magnetic resonance. J Allergy Clin Immunol 2015; 137:417-25. [PMID: 26242298 DOI: 10.1016/j.jaci.2015.06.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 05/29/2015] [Accepted: 06/17/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND The multiple-breath inert gas washout parameter acinar ventilation heterogeneity (Sacin) is thought to be a marker of acinar airway involvement but has not been validated by using quantitative imaging techniques in asthmatic patients. OBJECTIVE We aimed to use hyperpolarized (3)He diffusion magnetic resonance at multiple diffusion timescales and quantitative computed tomographic (CT) densitometry to determine the nature of acinar airway involvement in asthmatic patients. METHODS Thirty-seven patients with asthma and 17 age-matched healthy control subjects underwent spirometry, body plethysmography, multiple-breath inert gas washout (with the tracer gas sulfur hexafluoride), and hyperpolarized (3)He diffusion magnetic resonance. A subset of asthmatic patients (n = 27) underwent quantitative CT densitometry. RESULTS Ninety-four percent (16/17) of patients with an increased Sacin had Global Initiative for Asthma treatment step 4 to 5 asthma, and 13 of 17 had refractory disease. The apparent diffusion coefficient (ADC) of (3)He at 1 second was significantly higher in patients with Sacin-high asthma compared with that in healthy control subjects (0.024 vs 0.017, P < .05). Sacin correlated strongly with ADCs at 1 second (R = 0.65, P < .001) but weakly with ADCs at 13 ms (R = 0.38, P < .05). ADCs at both 13 ms and 1 second correlated strongly with the mean lung density expiratory/inspiratory ratio, a CT marker of expiratory air trapping (R = 0.77, P < .0001 for ADCs at 13 ms; R = 0.72, P < .001 for ADCs at 1 second). CONCLUSION Sacin is associated with alterations in long-range diffusion within the acinar airways and gas trapping. The precise anatomic nature and mechanistic role in patients with severe asthma requires further evaluation.
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Walkup LL, Woods JC. Translational applications of hyperpolarized 3He and 129Xe. NMR IN BIOMEDICINE 2014; 27:1429-1438. [PMID: 24953709 DOI: 10.1002/nbm.3151] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/07/2014] [Accepted: 05/19/2014] [Indexed: 06/03/2023]
Abstract
Clinical magnetic resonance imaging of the lung is technologically challenging, yet over the past two decades hyperpolarized noble gas ((3)He and (129)Xe) imaging has demonstrated the ability to measure multiple pulmonary functional biomarkers. There is a growing need for non-ionizing, non-invasive imaging techniques due to increased concern about cancer risk from ionizing radiation, but the translation of hyperpolarized gas imaging to the pulmonary clinic has been stunted by limited access to the technology. New developments may open doors to greater access and more translation to clinical studies. Here we briefly review a few translational applications of hyperpolarized gas MRI in the contexts of ventilation, diffusion, and dissolved-phase imaging, as well as comparing and contrasting (3)He and (129)Xe gases for these applications. Simple static ventilation MRI reveals regions of the lung not participating in normal ventilation, and these defects have been observed in many pulmonary diseases. Biomarkers related to airspace size and connectivity can be quantified by apparent diffusion coefficient measurements of hyperpolarized gas, and have been shown to be more sensitive to small changes in lung morphology than standard clinical pulmonary functional tests and have been validated by quantitative histology. Parameters related to gas uptake and exchange and lung tissue density can be determined using (129)Xe dissolved-phase MRI. In most cases functional biomarkers can be determined via MRI of either gas, but for some applications one gas may be preferred, such as (3)He for long-range diffusion measurements and (129)Xe for dissolved-phase imaging. Greater access to hyperpolarized gas imaging coupled with newly developing therapeutics makes pulmonary medicine poised for a potential revolution, further adding to the prospects of personalized medicine already evidenced by advancements in molecular biology. Hyperpolarized gas researchers have the opportunity to contribute to this revolution, particularly if greater clinical application of hyperpolarized gas imaging is realized.
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Affiliation(s)
- Laura L Walkup
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Burrowes KS, Doel T, Brightling C. Computational modeling of the obstructive lung diseases asthma and COPD. J Transl Med 2014; 12 Suppl 2:S5. [PMID: 25471125 PMCID: PMC4255909 DOI: 10.1186/1479-5876-12-s2-s5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Asthma and chronic obstructive pulmonary disease (COPD) are characterized by airway obstruction and airflow limitation and pose a huge burden to society. These obstructive lung diseases impact the lung physiology across multiple biological scales. Environmental stimuli are introduced via inhalation at the organ scale, and consequently impact upon the tissue, cellular and sub-cellular scale by triggering signaling pathways. These changes are propagated upwards to the organ level again and vice versa. In order to understand the pathophysiology behind these diseases we need to integrate and understand changes occurring across these scales and this is the driving force for multiscale computational modeling. There is an urgent need for improved diagnosis and assessment of obstructive lung diseases. Standard clinical measures are based on global function tests which ignore the highly heterogeneous regional changes that are characteristic of obstructive lung disease pathophysiology. Advances in scanning technology such as hyperpolarized gas MRI has led to new regional measurements of ventilation, perfusion and gas diffusion in the lungs, while new image processing techniques allow these measures to be combined with information from structural imaging such as Computed Tomography (CT). However, it is not yet known how to derive clinical measures for obstructive diseases from this wealth of new data. Computational modeling offers a powerful approach for investigating this relationship between imaging measurements and disease severity, and understanding the effects of different disease subtypes, which is key to developing improved diagnostic methods. Gaining an understanding of a system as complex as the respiratory system is difficult if not impossible via experimental methods alone. Computational models offer a complementary method to unravel the structure-function relationships occurring within a multiscale, multiphysics system such as this. Here we review the current state-of-the-art in techniques developed for pulmonary image analysis, development of structural models of the respiratory system and predictions of function within these models. We discuss application of modeling techniques to obstructive lung diseases, namely asthma and emphysema and the use of models to predict response to therapy. Finally we introduce a large European project, AirPROM that is developing multiscale models to investigate structure-function relationships in asthma and COPD.
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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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Stewart NJ, Leung G, Norquay G, Marshall H, Parra-Robles J, Murphy PS, Schulte RF, Elliot C, Condliffe R, Griffiths PD, Kiely DG, Whyte MK, Wolber J, Wild JM. Experimental validation of the hyperpolarized129Xe chemical shift saturation recovery technique in healthy volunteers and subjects with interstitial lung disease. Magn Reson Med 2014; 74:196-207. [DOI: 10.1002/mrm.25400] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 07/15/2014] [Accepted: 07/15/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Neil J. Stewart
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - General Leung
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Graham Norquay
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Helen Marshall
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Juan Parra-Robles
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | | | | | - Charlie Elliot
- Academic Directorate of Respiratory Medicine; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
- Sheffield Pulmonary Vascular Disease Unit; Sheffield Teaching Hospitals, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Robin Condliffe
- Academic Directorate of Respiratory Medicine; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
- Sheffield Pulmonary Vascular Disease Unit; Sheffield Teaching Hospitals, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Paul D. Griffiths
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - David G. Kiely
- Academic Directorate of Respiratory Medicine; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
- Sheffield Pulmonary Vascular Disease Unit; Sheffield Teaching Hospitals, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Moira K. Whyte
- Academic Directorate of Respiratory Medicine; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
| | - Jan Wolber
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
- Medical Diagnostics; GE Healthcare; Amersham United Kingdom
| | - Jim M. Wild
- Academic Unit of Radiology; University of Sheffield, Royal Hallamshire Hospital; Sheffield United Kingdom
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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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Guo J, Huang HJ, Wang X, Wang W, Ellison H, Thomen RP, Gelman AE, Woods JC. Imaging mouse lung allograft rejection with (1)H MRI. Magn Reson Med 2014; 73:1970-8. [PMID: 24954886 DOI: 10.1002/mrm.25313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 05/05/2014] [Accepted: 05/18/2014] [Indexed: 12/24/2022]
Abstract
PURPOSE To demonstrate that longitudinal, noninvasive monitoring via MRI can characterize acute cellular rejection in mouse orthotopic lung allografts. METHODS Nineteen Balb/c donor to C57BL/6 recipient orthotopic left lung transplants were performed, further divided into control-Ig versus anti-CD4/anti-CD8 treated groups. A two-dimensional multislice gradient-echo pulse sequence synchronized with ventilation was used on a small-animal MR scanner to acquire proton images of lung at postoperative days 3, 7, and 14, just before sacrifice. Lung volume and parenchymal signal were measured, and lung compliance was calculated as volume change per pressure difference between high and low pressures. RESULTS Normalized parenchymal signal in the control-Ig allograft increased over time, with statistical significance between day 14 and day 3 posttransplantation (0.046→0.789; P < 0.05), despite large intermouse variations; this was consistent with histopathologic evidence of rejection. Compliance of the control-Ig allograft decreased significantly over time (0.013→0.003; P < 0.05), but remained constant in mice treated with anti-CD4/anti-CD8 antibodies. CONCLUSION Lung allograft rejection in individual mice can be monitored by lung parenchymal signal changes and by lung compliance through MRI. Longitudinal imaging can help us better understand the time course of individual lung allograft rejection and response to treatment.
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Affiliation(s)
- Jinbang Guo
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Department of Physics, Washington University in St. Louis, St. Louis, Missouri, USA
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Abstract
Non-uniform distribution of inspired gas within the lung, termed ventilation heterogeneity, is present in patients with even mild asthma. Current evidence strongly supports ventilation heterogeneity as a fundamental derangement of lung function in asthma that contributes per se to hypoxemia and airway hyper-responsiveness. An extreme example of ventilation heterogeneity is the identification by hyperpolarized gas MRI of lung regions with no ventilation, termed filling defects. Lung filling defects in patients with asthma can persist over time, increase in size with methacholine-induced bronchospasm and more likely are caused by obstruction of the peripheral and not the proximal airways. Ventilation heterogeneity can be quantified in the conducting and acinar lung zones with the multiple gas washout method, and in the acinar zone does not fully resolve following bronchodilator treatment in patients with asthma. In prospective studies, the degree of ventilation heterogeneity at baseline predicts airway hyper-responsiveness and response to corticosteroid dose titration. An important unanswered question is the relationship of airways inflammation to ventilation heterogeneity. In consideration of the importance of ventilation heterogeneity in its pathobiology, asthma is more a focal disorder with regional pathology akin to regional ileitis and not the generalized disorder of the airways as it has been viewed in the past.
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Affiliation(s)
- W Gerald Teague
- Division of Respiratory Medicine, Allergy, and Immunology, Department of Pediatrics and
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Bernardin L, Douglas NHM, Collins DJ, Giles SL, O'Flynn EAM, Orton M, deSouza NM. Diffusion-weighted magnetic resonance imaging for assessment of lung lesions: repeatability of the apparent diffusion coefficient measurement. Eur Radiol 2014; 24:502-11. [PMID: 24275802 DOI: 10.1007/s00330-013-3048-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 09/25/2013] [Accepted: 09/30/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE To establish repeatability of apparent diffusion coefficients (ADCs) acquired from free-breathing diffusion-weighted magnetic resonance imaging (DW-MRI) in malignant lung lesions and investigate effects of lesion size, location and respiratory motion. METHODS Thirty-six malignant lung lesions (eight patients) were examined twice (1- to 5-h interval) using T1-weighted, T2-weighted and axial single-shot echo-planar DW-MRI (b = 100, 500, 800 s/mm(2)) during free-breathing. Regions of interest around target lesions on computed b = 800 s/mm(2) images by two independent observers yielded ADC values from maps (pixel-by-pixel fitting using all b values and a mono-exponential decay model). Intra- and inter-observer repeatability was assessed per lesion, per patient and by lesion size (> or <2 cm) or location. RESULTS ADCs were similar between observers (mean ± SD, 1.15 ± 0.28 × 10(-3) mm(2)/s, observer 1; 1.15 ± 0.29 × 10(-3) mm(2)/s, observer 2). Intra-observer coefficients of variation of the mean [median] ADC per lesion and per patient were 11% [11.4%], 5.7% [5.7%] for observer 1 and 9.2% [9.5%], 3.9% [4.7%] for observer 2 respectively; inter-observer values were 8.9% [9.3%] (per lesion) and 3.0% [3.7%] (per patient). Inter-observer coefficient of variation (CoV) was greater for lesions <2 cm (n = 20) compared with >2 cm (n = 16) (10.8% vs 6.5% ADCmean, 11.3% vs 6.7% ADCmedian) and for mid (n = 14) vs apical (n = 9) or lower zone (n = 13) lesions (13.9%, 2.7%, 3.8% respectively ADCmean; 14.2%, 2.8%, 4.7% respectively ADCmedian). CONCLUSION Free-breathing DW-MRI of whole lung achieves good intra- and inter-observer repeatability of ADC measurements in malignant lung tumours. KEY POINTS • Diffusion-weighted MRI of the lung can be satisfactorily acquired during free-breathing • DW-MRI demonstrates high contrast between primary and metastatic lesions and normal lung • Apparent diffusion coefficient (ADC) measurements in lung tumours are repeatable and reliable • ADC offers potential in assessing response in lung metastases in clinical trials.
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Affiliation(s)
- L Bernardin
- CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Surrey, SM2 5PT, UK
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Wang C, Mugler JP, de Lange EE, Patrie JT, Mata JF, Altes TA. Lung injury induced by secondhand smoke exposure detected with hyperpolarized helium-3 diffusion MR. J Magn Reson Imaging 2014; 39:77-84. [PMID: 24123388 PMCID: PMC5072395 DOI: 10.1002/jmri.24104] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 02/11/2013] [Indexed: 01/19/2023] Open
Abstract
PURPOSE To determine whether helium-3 diffusion MR can detect the changes in the lungs of healthy nonsmoking individuals who were regularly exposed to secondhand smoke. MATERIALS AND METHODS Three groups were studied (age: 59 ± 9 years): 23 smokers, 37 exposure-to-secondhand-smoke subjects, and 29 control subjects. We measured helium-3 diffusion values at diffusion times from 0.23 to 1.97 s. RESULTS One-way analysis of variance revealed that the mean area under the helium-3 diffusion curves (ADC AUC) of the smokers was significantly elevated compared with the controls and to the exposure-to-secondhand-smoke subjects (P < 0.001 both). No difference between the mean ADC AUC of the exposure-to-secondhand-smoke subjects and that of the controls was found (P = 0.115). However, application of a receiver operator characteristic-derived rule to classify subjects as either a "control" or a "smoker," based on ADC AUC, revealed that 30% (11/37) of the exposure-to-secondhand subjects were classified as "smokers" indicating an elevation of the ADC AUC. CONCLUSION Using helium-3 diffusion MR, elevated ADC values were detected in 30% of nonsmoking healthy subjects who had been regularly exposed to secondhand smoke, supporting the concept that, in susceptible individuals, secondhand smoke causes mild lung damage.
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Affiliation(s)
- Chengbo Wang
- Faculty of Science and Engineering, University of Nottingham Ningbo China, Ningbo, China
- Department of Radiology and Medical Imaging, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - John P. Mugler
- Department of Radiology and Medical Imaging, School of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Eduard E. de Lange
- Department of Radiology and Medical Imaging, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - James T. Patrie
- Public Health Science, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Jaime F. Mata
- Department of Radiology and Medical Imaging, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Talissa A. Altes
- Department of Radiology and Medical Imaging, School of Medicine, University of Virginia, Charlottesville, VA, USA
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Bianchi A, Ozier A, Ousova O, Raffard G, Crémillieux Y. Ultrashort-TE MRI longitudinal study and characterization of a chronic model of asthma in mice: inflammation and bronchial remodeling assessment. NMR IN BIOMEDICINE 2013; 26:1451-1459. [PMID: 23761222 DOI: 10.1002/nbm.2975] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 06/02/2023]
Abstract
Asthma is a chronic disease characterized by bronchial hyperresponsiveness (BHR), bronchial inflammation and remodeling. The great improvements in (1)H MRI ultrashort-TE (UTE) sequences in the last decade have allowed lung images with high-resolution and good signal-to-noise ratio to be obtained in parenchymal tissues. In this article, we present a UTE (1)H MRI high-resolution study of a chronic model of asthma in mice with the aim to longitudinally assess the main features of asthma using a fully noninvasive approach. Balb/c mice (n = 6) were sensitized with ovalbumin over a period of 75 days. The control group (n = 3) received normal saline on the same days. MRI acquisitions were performed on days 0, 38 and 78 to study the inflammatory volumes and bronchial remodeling (peribronchial signal intensity index, PBSI). Plethysmographic studies were performed on days 0, 39 and 79 to assess BHR to methacholine using the enhanced pause (Penh) ratio. The average inflammatory volume measured by MRI in the ovalbumin group (15.6 ± 2.4 μL) was increased significantly relative to control mice (-0.3 ± 0.7 μL) on day 38. The inflammatory volume was larger (34.2 ± 3.1 μL) on day 78 in the ovalbumin group. PBSI was significantly higher in the ovalbumin group on day 78 (1.53 ± 0.08) relative to the control group (1.16 ± 0.10), but not on day 38. After sensitization, asthmatic mice presented BHR to methacholine on days 39 and 79. Penh ratios correlated significantly with the inflammatory volume on day 39 and with the PBSI on day 79. This study shows, for the first time, that high-resolution UTE (1)H MRI of the lungs may allow the noninvasive quantification of peribronchial eosinophilic inflammation with airways occlusion by mucus and of bronchial remodeling in a murine asthma model that correlates with functional parameters.
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Affiliation(s)
- Andrea Bianchi
- Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, Université Bordeaux Segalen, Bordeaux, France; Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, Université Bordeaux Segalen, Bordeaux, France
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Abstract
A better understanding of the anatomic structure and physiological function of the lung is fundamental to understanding the pathogenesis of pulmonary disease and how to design and deliver better treatments and measure response to intervention. Magnetic resonance imaging (MRI) with the hyperpolarised noble gases helium-3 ((3)He) and xenon-129 ((129)Xe) provides both structural and functional pulmonary measurements, and because it does not require the use of x-rays or other ionising radiation, offers the potential for intensive serial and longitudinal studies in paediatric patients. These facts are particularly important in the evaluation of chronic lung diseases such as asthma and cystic fibrosis- both of which can be considered paediatric respiratory diseases with unmet therapy needs. This review discusses MRI-based imaging methods with a focus on hyperpolarised gas MRI. We also discuss the strengths and limitations as well as the future work required for clinical translation towards paediatric respiratory disease.
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Affiliation(s)
- Miranda Kirby
- Imaging Research Laboratories, Robarts Research Institute, London, Canada.
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Insights into pediatric asthma with hyperpolarized magnetic resonance imaging of the lung. J Allergy Clin Immunol 2013; 131:377-8. [PMID: 23374266 DOI: 10.1016/j.jaci.2012.12.669] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 11/23/2022]
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Walker C, Gupta S, Raj V, Siddiqui S, Brightling CE. Imaging advances in asthma. ACTA ACUST UNITED AC 2013; 5:453-65. [PMID: 23484630 DOI: 10.1517/17530059.2011.609886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Asthma is a global burden, affecting 5% of the general adult population, with approximately 5 - 10% suffering from severe asthma. Severe asthma is a complex heterogeneous disease entity, with high morbidity and mortality. Recent years have seen the introduction of a vast array of new imaging technologies, which have provided the ability to comprehensively, non-invasively and functionally assess the lungs. These advances have resulted in a better understanding of the pathophysiology in severe asthma and have the unprecedented potential to unravel the structure-function relationship of severe asthma in the future. AREAS COVERED This review article chronologically describes the technological advances currently used and to be used in the future. The article covers pitfalls in imaging of the airways and lung parenchyma in asthma from chest x-rays, CT scans, MRI, confocal florescence endomicroscopy to computational fluid dynamics. EXPERT OPINION Novel qualitative and quantitative imaging techniques have enabled us to study the large airway architecture in detail, assess the small airway structure and perform functional or novel physiological evaluations. Despite spectacular advances in imaging techniques and the birth of new modalities, there is an urgent need for both proof-of-concept studies, large cross-sectional and longitudinal clinical trials in severe asthma to validate and clinically correlate imaging-derived measures. This will extend our current understanding of the pathophysiology of severe asthma, and unravel the structure-function relationship, with the potential to discover novel severe asthma phenotypes, predict mortality, morbidity and response to existing and novel pharmacological and non-pharmacological therapies.
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Affiliation(s)
- Carolina Walker
- University of Leicester , Institute for Lung Health, Department of Infection , Inflammation and Immunity, Leicester , UK
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Costella S, Kirby M, Maksym GN, McCormack DG, Paterson NAM, Parraga G. Regional pulmonary response to a methacholine challenge using hyperpolarized (3)He magnetic resonance imaging. Respirology 2013; 17:1237-46. [PMID: 22889229 DOI: 10.1111/j.1440-1843.2012.02250.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVE Spirometry is insensitive to small airway abnormalities in asthma. Our objective was to evaluate regional lung structure and function using hyperpolarized (3)He magnetic resonance imaging (MRI) before, during and after a methacholine challenge (MCh). METHODS Twenty-five asthmatics (mean age = 34 ± 11 years) and eight healthy volunteers (HV) (mean age = 33 ± 11 years) underwent spirometry, plethysmography and hyperpolarized (3)He MRI prior to a MCh. MRI was repeated following the MCh and again 25 min after salbutamol administration. (3)He MRI gas distribution was quantified using semiautomated segmentation of the ventilation defect percent (VDP). Tissue microstructure was measured using the (3)He apparent diffusion coefficient (ADC). Analysis of variance with repeated measures was used to evaluate changes at each time point as well as to determine interactions between regions of interest (ROI) and subject group. Pearson's correlations were performed to evaluate associations between (3)He MRI measurements and established clinical measures. RESULTS In asthmatics, but not HV, whole-lung ADC was increased post-MCh (P < 0.01). In asthmatics only, ADC was increased post-MCh in posterior ROI (P < 0.01) and all ROI in the superior-inferior direction (P < 0.01). VDP was increased in posterior and inferior ROI (P < 0.001). There was a correlation between VDP and specific airway resistance (r = 0.74, P < 0.0001), dyspnoea score (r = 0.66, P < 0.01) and fractional exhaled nitric oxide (r = 0.45, P < 0.05). CONCLUSIONS We evaluated the regional pulmonary response to methacholine and salbutamol using (3)He MRI and showed heterogeneous VDP and ADC consistent with bronchoconstriction and gas trapping, respectively, post-MCh. These regional alterations resolved post-salbutamol.
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Affiliation(s)
- Stephen Costella
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada
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Abstract
Pulmonary emphysema is a pathologic condition characterized by permanently enlarged airspaces distal to the terminal bronchiole with destruction of the alveolar walls. Functional information of the lungs is important to understand the pathophysiology of emphysema and that of chronic obstructive pulmonary disease. With the recent developments in magnetic resonance imaging (MRI) techniques, functional MRI with variable MR sequences can be used for the evaluation of different physiological and anatomic changes seen in cases of pulmonary emphysema. In this review article, we will focus on a brief description of each method, results of some of the most recent work, and the clinical application of such knowledge.
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Thompson BR, Douglass JA, Ellis MJ, Kelly VJ, O'Hehir RE, King GG, Verbanck S. Peripheral lung function in patients with stable and unstable asthma. J Allergy Clin Immunol 2013; 131:1322-8. [PMID: 23561802 DOI: 10.1016/j.jaci.2013.01.054] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 01/22/2013] [Accepted: 01/24/2013] [Indexed: 11/20/2022]
Abstract
BACKGROUND Exacerbations of asthma are thought to be caused by airflow obstruction resulting from airway inflammation, bronchospasm, and mucus plugging. Histologic evidence suggests the small airways, including acinar air spaces, are involved; however, this has not been corroborated in vivo by measurements of peripheral small-airway function. OBJECTIVE We sought to determine whether asthma severity is linked to small-airway function, particularly in patients with acute severe asthma. METHODS Eighteen subjects admitted for an asthma exacerbation underwent lung function testing, including measures of acinar ventilation heterogeneity (S(acin)) and conductive ventilation heterogeneity (S(cond)) using the multiple-breath nitrogen washout. Treatment requirement was defined according to Global Initiative for Asthma scores. Data were compared with those obtained in 19 patients with stable asthma. RESULTS For the asthma exacerbation group, the median FEV1 was 59% of predicted value (95% CI, 45% to 75% of predicted value), the median S(cond) value was 185% of predicted value (95% CI, 119% to 245% of predicted value), and the median S(acin) value was 225% of predicted value (95% CI, 143% to 392% of predicted value). FEV1 (percent predicted) was correlated with S(acin) (percent predicted) values (Spearman rho = -0.67, P = .006) but not with S(cond) (percent predicted) values (P > .1). The Global Initiative for Asthma score was significantly related to S(acin) (percent predicted) (Spearman rho = 0.59, P = .016) but not to S(cond) (percent predicted) values (P > .1). The unstable group was characterized by considerably lower forced vital capacity (P < .001) and higher S(cond) (P = .001) values than the unstable group. In a subgroup of 11 unstable patients who could be reviewed after 4 weeks, FEV1, forced vital capacity, S(acin), and S(cond) values showed marked improvements. CONCLUSION Our findings suggest that unstable asthma is characterized by a combined abnormality in the acinar and conductive lung zones, both of which are partly reversible. Functional abnormality in the acinar lung zone in particular showed a direct correlation with airflow obstruction and treatment requirement in patients with acute severe asthma.
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Affiliation(s)
- Bruce R Thompson
- Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital and Monash University, Melbourne, Australia.
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Safiullin K, Talbot C, Nacher PJ. Achieving high spatial resolution and high SNR in low-field MRI of hyperpolarised gases with Slow Low Angle SHot. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 227:72-86. [PMID: 23314002 DOI: 10.1016/j.jmr.2012.11.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 10/26/2012] [Accepted: 11/24/2012] [Indexed: 06/01/2023]
Abstract
MRI of hyperpolarised gases is usually performed with fast data acquisition to achieve high spatial resolutions despite rapid diffusion-induced signal attenuation. We describe a double-cross k-space sampling scheme suitable for Slow Low Angle SHot (SLASH) acquisition and yielding an increased SNR. It consists of a series of anisotropic partial acquisitions with a reduced resolution in the read direction, which alleviates signal attenuation and still provides a high isotropic resolution. The advantages of SLASH imaging over conventional FLASH imaging are evaluated analytically, using numerical lattice calculations, and experimentally in phantom cells filled with hyperpolarised (3)He-N(2) gas mixtures. Low-field MRI is performed (here 2.7 mT), a necessary condition to obtain long T(2)(∗) values in lungs for slow acquisition. Two additional benefits of the SLASH scheme over FLASH imaging have been demonstrated: it is less sensitive to the artefacts due to concomitant gradients and it allows measuring apparent diffusion coefficients for an extended range of times.
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Cadman RV, Lemanske RF, Evans MD, Jackson DJ, Gern JE, Sorkness RL, Fain SB. Pulmonary 3He magnetic resonance imaging of childhood asthma. J Allergy Clin Immunol 2012; 131:369-76.e1-5. [PMID: 23246019 DOI: 10.1016/j.jaci.2012.10.032] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 10/03/2012] [Accepted: 10/05/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND Magnetic resonance imaging (MRI) with (3)He does not require ionizing radiation and has been shown to detect regional abnormalities in lung ventilation and structure in adults with asthma, but the method has not been extended to children with asthma. Measurements of regional lung ventilation and microstructure in subjects with childhood asthma could advance our understanding of disease mechanisms. OBJECTIVE We sought to determine whether (3)He MRI in children can identify abnormalities related to the diagnosis of asthma or prior history of respiratory illness. METHODS Forty-four children aged 9 to 10 years were recruited from a birth cohort at increased risk of asthma and allergic diseases. For each subject, a time-resolved 3-dimensional image series and a 3-dimensional diffusion-weighted image were acquired in separate breathing maneuvers. The numbers and sizes of ventilation defects were scored, and regional maps and statistics of average (3)He diffusion lengths were calculated. RESULTS Children with mild-to-moderate asthma had lower average root-mean-square diffusion length (X(rms)) values (P = .004), increased regional SD of diffusion length values (P = .03), and higher defect scores (P = .03) than those without asthma. Children with histories of wheezing illness with rhinovirus infection before the third birthday had lower X(rms) values (P = .01) and higher defect scores (P = .05). CONCLUSION MRI with (3)He detected more and larger regions of ventilation defect and a greater degree of restricted gas diffusion in children with asthma compared with those seen in children without asthma. These measures are consistent with regional obstruction and smaller and more regionally variable dimensions of the peripheral airways and alveolar spaces.
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Affiliation(s)
- Robert V Cadman
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wis 53705, USA
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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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Usmani OS, Barnes PJ. Assessing and treating small airways disease in asthma and chronic obstructive pulmonary disease. Ann Med 2012; 44:146-56. [PMID: 21679101 DOI: 10.3109/07853890.2011.585656] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory disorders of the respiratory tract that are characterized by airflow limitation. They are distinct conditions with different causes, structural changes, and immunopathology. The pathophysiology in asthma and COPD involves not only the proximal large airways, but also the distal small airways, and thus the small airways are an important therapeutic target in the treatment of both diseases. The assessment of diseased distal small airways is challenging. Extensive disease can be present in the small airways with little abnormality in conventional pulmonary function tests. Recent advances in imaging technologies have led to better spatial resolution to assess small airways morphology non-invasively. New physiological tests have been developed to detect disease and response to therapy in regional airways. Improving the efficiency of existing aerosolized therapy to direct drug to the appropriate lung regions may improve clinical efficacy. Approaches to target distal lung regions include developing new drug formulations with smaller aerosol particle size or using inhaler devices that emit aerosolized drug at slow inhalation flows. Large studies are needed to determine whether better distal lung deposition leads to improvements in small airways function that are translated into clinically significant patient outcomes.
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Affiliation(s)
- Omar S Usmani
- Airway Disease Section, National Heart and Lung Institute, Imperial College, London, UK.
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Abstract
Pulmonary magnetic resonance (MR) imaging has been put forward as a new research and diagnostic tool mainly to overcome the limitations of computed tomography and nuclear medicine studies. However, pulmonary MR imaging has been difficult to use because of inherently low proton density, a multitude of air-tissue interfaces, which create significant magnetic field distortions and are commonly referred to as susceptibility artifacts; diminishing signal in the lung; and respiratory and/or cardiac motion artifacts. To overcome these drawbacks of pulmonary MR imaging, technical advances made during the last decade in sequencing, scanner and coil, adaptation of parallel imaging techniques, and utilization of contrast media have been reported as being useful for functional and morphologic assessment of various pulmonary diseases including airway diseases. This review article covers (1) pulmonary MR techniques for morphologic and functional assessment of airway diseases, and (2) pulmonary MR imaging for cystic fibrosis, asthma, and chronic obstructive pulmonary disease. Pulmonary MR imaging provides not only morphology-related but also pulmonary function-related information. It has the potential to replace nuclear medicine studies for the identification of regional pulmonary function and may perform a complementary role in airway disease assessment instead of nuclear medicine study. We believe that the findings of further basic studies as well as clinical applications of this new technique will validate the real significance of pulmonary MR imaging for the future of airway disease assessment and its usefulness for diagnostic radiology and pulmonary medicine.
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Imai F, Kashiwagi R, Imai H, Iguchi S, Kimura A, Fujiwara H. Hyperpolarized 129Xe MR imaging with balanced steady-state free precession in spontaneously breathing mouse lungs. Magn Reson Med Sci 2011; 10:33-40. [PMID: 21441726 DOI: 10.2463/mrms.10.33] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE We investigated the characteristics of hyperpolarized (HP) (129)Xe magnetic resonance (MR) imaging obtained from balanced steady-state free precession (SSFP) measurement of mouse lungs, especially under spontaneous breathing, and compared the results with those obtained using traditional spoiled gradient echo (SPGR) method, focusing on improved signal-to-noise ratio (SNR) and reduced total acquisition time. METHODS We calculated magnetization response of the HP (129)Xe gas for the balanced SSFP sequence under spontaneous breathing to derive optimal conditions for the imaging experiment. We then placed an anesthetized mouse in the magnet (9.4T) supplied with oxygen gas and a mixture of HP (129)Xe gas supplied from a continuous-flow hyperpolarizing system. We obtained an axial plane image of the lung through balanced SSFP and SPGR sequences, changing the various magnetic resonance (MR) imaging parameters, and measured the SNR of these images. RESULTS We demonstrated the clear dependence of image intensity on flip angle and number of shots. The SNR was higher in balanced SSFP than in SPGR and 2.3-fold higher compared at each maximum. In contrast, total acquisition time in balanced SSFP was shortened to about one-eighth that of SPGR using a one-shot acquisition mode. CONCLUSION In HP (129)Xe MR imaging of the lung of a spontaneously breathing mouse, balanced SSFP sequence with multi-shot and centric order acquisition provides higher SNR in a shorter acquisition time than SPGR.
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Affiliation(s)
- Fumito Imai
- Division of Medical Physics and Engineering, Area of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Osaka University, Suita, Japan.
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Lung imaging in asthmatic patients: the picture is clearer. J Allergy Clin Immunol 2011; 128:467-78. [PMID: 21636118 DOI: 10.1016/j.jaci.2011.04.051] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 04/10/2011] [Accepted: 04/18/2011] [Indexed: 01/11/2023]
Abstract
Imaging of the lungs in patients with asthma has evolved dramatically over the last decade with sophisticated techniques, such as computed tomography, magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography. New insights into current and future modalities for imaging in asthmatic patients and their application are discussed to potentially shed a clearer picture of the underlying pathophysiology of asthma, especially severe asthma, and the proposed clinical utility of imaging in patients with this common disease.
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