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Xiao Q, Stewart NJ, Willmering MM, Gunatilaka CC, Thomen RP, Schuh A, Krishnamoorthy G, Wang H, Amin RS, Dumoulin CL, Woods JC, Bates AJ. Human upper-airway respiratory airflow: In vivo comparison of computational fluid dynamics simulations and hyperpolarized 129Xe phase contrast MRI velocimetry. PLoS One 2021; 16:e0256460. [PMID: 34411195 PMCID: PMC8376109 DOI: 10.1371/journal.pone.0256460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 08/08/2021] [Indexed: 11/18/2022] Open
Abstract
Computational fluid dynamics (CFD) simulations of respiratory airflow have the potential to change the clinical assessment of regional airway function in health and disease, in pulmonary medicine and otolaryngology. For example, in diseases where multiple sites of airway obstruction occur, such as obstructive sleep apnea (OSA), CFD simulations can identify which sites of obstruction contribute most to airway resistance and may therefore be candidate sites for airway surgery. The main barrier to clinical uptake of respiratory CFD to date has been the difficulty in validating CFD results against a clinical gold standard. Invasive instrumentation of the upper airway to measure respiratory airflow velocity or pressure can disrupt the airflow and alter the subject's natural breathing patterns. Therefore, in this study, we instead propose phase contrast (PC) velocimetry magnetic resonance imaging (MRI) of inhaled hyperpolarized 129Xe gas as a non-invasive reference to which airflow velocities calculated via CFD can be compared. To that end, we performed subject-specific CFD simulations in airway models derived from 1H MRI, and using respiratory flowrate measurements acquired synchronously with MRI. Airflow velocity vectors calculated by CFD simulations were then qualitatively and quantitatively compared to velocity maps derived from PC velocimetry MRI of inhaled hyperpolarized 129Xe gas. The results show both techniques produce similar spatial distributions of high velocity regions in the anterior-posterior and foot-head directions, indicating good qualitative agreement. Statistically significant correlations and low Bland-Altman bias between the local velocity values produced by the two techniques indicates quantitative agreement. This preliminary in vivo comparison of respiratory airway CFD and PC MRI of hyperpolarized 129Xe gas demonstrates the feasibility of PC MRI as a technique to validate respiratory CFD and forms the basis for further comprehensive validation studies. This study is therefore a first step in the pathway towards clinical adoption of respiratory CFD.
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Affiliation(s)
- Qiwei Xiao
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
| | - Neil J. Stewart
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Department of Infection, Immunity & Cardiovascular Disease, POLARIS Group, Imaging Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Matthew M. Willmering
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
| | - Chamindu C. Gunatilaka
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
| | - Robert P. Thomen
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Pulmonary Imaging Research Laboratory, University of Missouri School of Medicine, Columbia, Missouri, United States of America
| | - Andreas Schuh
- Department of Computing, Imperial College London, London, United Kingdom
| | | | - Hui Wang
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- MR Clinical Science, Philips, Cincinnati, OH, United States of America
| | - Raouf S. Amin
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati School of Medicine, Cincinnati, OH, United States of America
| | - Charles L. Dumoulin
- Department of Radiology, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Jason C. Woods
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati School of Medicine, Cincinnati, OH, United States of America
- Department of Radiology, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Alister J. Bates
- Division of Pulmonary Medicine, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati School of Medicine, Cincinnati, OH, United States of America
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2
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Willmering MM, Niedbalski PJ, Wang H, Walkup LL, Robison RK, Pipe JG, Cleveland ZI, Woods JC. Improved pulmonary 129 Xe ventilation imaging via 3D-spiral UTE MRI. Magn Reson Med 2019; 84:312-320. [PMID: 31788858 DOI: 10.1002/mrm.28114] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 02/03/2023]
Abstract
PURPOSE Hyperpolarized 129 Xe MRI characterizes regional lung ventilation in a variety of disease populations, with high sensitivity to airway obstruction in early disease. However, ventilation images are usually limited to a single breath-hold and most-often acquired using gradient-recalled echo sequences with thick slices (~10-15 mm), which increases partial-volume effects, limits ability to observe small defects, and suffers from imperfect slice selection. We demonstrate higher-resolution ventilation images, in shorter breath-holds, using FLORET (Fermat Looped ORthogonally Encoded Trajectories), a center-out 3D-spiral UTE sequence. METHODS In vivo human adult (N = 4; 2 healthy, 2 with cystic fibrosis) 129 Xe images were acquired using 2D gradient-recalled echo, 3D radial, and FLORET. Each sequence was acquired at its highest possible resolution within a 16-second breath-hold with a minimum voxel dimension of 3 mm. Images were compared using 129 Xe ventilation defect percentage, SNR, similarity coefficients, and vasculature cross-sections. RESULTS The FLORET sequence obtained relative normalized SNR, 40% greater than 2D gradient-recalled echo (P = .012) and 26% greater than 3D radial (P = .067). Moreover, the FLORET images were acquired with 3-fold-higher nominal resolution in a 15% shorter breath-hold. Finally, vasculature was less prominent in FLORET, likely due to diminished susceptibility-induced dephasing at shorter TEs afforded by UTE sequences. CONCLUSION The FLORET sequence yields higher SNR for a given resolution with a shorter breath-hold than traditional ventilation imaging techniques. This sequence more accurately measures ventilation abnormalities and enables reduced scan times in patients with poor compliance and severe lung disease.
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Affiliation(s)
- Matthew M Willmering
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Peter J Niedbalski
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Hui Wang
- Clinical Science, Philips, Cincinnati, Ohio.,Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Laura L Walkup
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio
| | - Ryan K Robison
- Department of Radiology, Phoenix Children's Hospital, Phoenix, Arizona
| | - James G Pipe
- Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - Zackary I Cleveland
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio.,Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio
| | - Jason C Woods
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio
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3
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Kim M, Collier GJ, Wild JM, Chung YM. Effect of upper airway on tracheobronchial fluid dynamics. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3112. [PMID: 29856119 DOI: 10.1002/cnm.3112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/24/2018] [Accepted: 05/27/2018] [Indexed: 05/17/2023]
Abstract
The upper airways play a significant role in the tracheal flow dynamics. Despite many previous studies, however, the effect of the upper airways on the ventilation distribution in distal airways has remained a challenge. The aim of this study is to experimentally and computationally investigate the dynamic behaviour in the intratracheal flow induced by the upper respiratory tract and to assess its influence on the subsequent tributaries. Patient-specific images from 2 different modalities (magnetic resonance imaging of the upper airways and computed tomography of the lower airways) were segmented and combined. An experimental phantom of patient-specific airways (including the oral cavity, larynx, trachea, down to generations 6-8) was generated using 3D printing. The flow velocities in this phantom model were measured by the flow-sensitised phase contrast magnetic resonance imaging technique and compared with the computational fluid dynamics simulations. Both experimental and computational results show a good agreement in the time-averaged velocity fields as well as fluctuating velocity. The flows in the proximal trachea were complex and unsteady under both lower- and higher-flow rate conditions. Computational fluid dynamics simulations were also performed with an airways model without the upper airways. Although the flow near the carina remained unstable only when the inflow rate was high, the influence of the upper airways caused notable changes in distal flow distributions when the 2 airways models were compared with and without the upper airways. The results suggest that the influence of the upper airways should be included in the respiratory flow assessment as the upper airways extensively affect the flows in distal airways and consequent ventilation distribution in the lungs.
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Affiliation(s)
- Minsuok Kim
- School of Engineering, University of Warwick, Coventry, UK
| | - Guilhem J Collier
- Academic Unit of Radiology, Institute for In Silico Medicine, University of Sheffield, Sheffield, UK
| | - Jim M Wild
- Academic Unit of Radiology, Institute for In Silico Medicine, University of Sheffield, Sheffield, UK
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4
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Collier GJ, Kim M, Chung Y, Wild JM. 3D phase contrast MRI in models of human airways: Validation of computational fluid dynamics simulations of steady inspiratory flow. J Magn Reson Imaging 2018; 48:1400-1409. [DOI: 10.1002/jmri.26039] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 03/20/2018] [Indexed: 12/19/2022] Open
Affiliation(s)
- Guilhem J. Collier
- POLARIS, Unit of Academic Radiology, Department of Infection; Immunity and Cardiovascular Disease, University of Sheffield; Sheffield UK
| | - Minsuok Kim
- School of Engineering and Centre for Scientific Computing; University of Warwick; Coventry UK
| | - Yongmann Chung
- School of Engineering and Centre for Scientific Computing; University of Warwick; Coventry UK
| | - Jim M. Wild
- POLARIS, Unit of Academic Radiology, Department of Infection; Immunity and Cardiovascular Disease, University of Sheffield; Sheffield UK
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Lizal F, Jedelsky J, Morgan K, Bauer K, Llop J, Cossio U, Kassinos S, Verbanck S, Ruiz-Cabello J, Santos A, Koch E, Schnabel C. Experimental methods for flow and aerosol measurements in human airways and their replicas. Eur J Pharm Sci 2018; 113:95-131. [DOI: 10.1016/j.ejps.2017.08.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/14/2017] [Accepted: 08/17/2017] [Indexed: 12/29/2022]
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6
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Doganay O, Matin TN, Mcintyre A, Burns B, Schulte RF, Gleeson FV, Bulte D. Fast dynamic ventilation MRI of hyperpolarized 129 Xe using spiral imaging. Magn Reson Med 2017; 79:2597-2606. [PMID: 28921655 PMCID: PMC5836876 DOI: 10.1002/mrm.26912] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 08/17/2017] [Accepted: 08/17/2017] [Indexed: 02/06/2023]
Abstract
Purpose To develop and optimize a rapid dynamic hyperpolarized 129Xe ventilation (DXeV) MRI protocol and investigate the feasibility of capturing pulmonary signal‐time curves in human lungs. Theory and Methods Spiral k‐space trajectories were designed with the number of interleaves Nint = 1, 2, 4, and 8 corresponding to voxel sizes of 8 mm, 5 mm, 4 mm, and 2.5 mm, respectively, for field of view = 15 cm. DXeV images were acquired from a gas‐flow phantom to investigate the ability of Nint = 1, 2, 4, and 8 to capture signal‐time curves. A finite element model was constructed to investigate gas‐flow dynamics corroborating the experimental signal‐time curves. DXeV images were also carried out in six subjects (three healthy and three chronic obstructive pulmonary disease subjects). Results DXeV images and numerical modelling of signal‐time curves permitted the quantification of temporal and spatial resolutions for different numbers of spiral interleaves. The two‐interleaved spiral (Nint = 2) was found to be the most time‐efficient to obtain DXeV images and signal‐time curves of whole lungs with a temporal resolution of 624 ms for 13 slices. Signal‐time curves were well matched in three healthy volunteers. The Spearman's correlations of chronic obstructive pulmonary disease subjects were statistically different from three healthy subjects (P < 0.05). Conclusion The Nint = 2 spiral demonstrates the successful acquisition of DXeV images and signal‐time curves in healthy subjects and chronic obstructive pulmonary disease patients. Magn Reson Med 79:2597–2606, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Ozkan Doganay
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, United Kingdom.,Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Road, Headington, OX3 7LE, United Kingdom
| | - Tahreema N Matin
- Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Road, Headington, OX3 7LE, United Kingdom
| | - Anthony Mcintyre
- Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Road, Headington, OX3 7LE, United Kingdom
| | - Brian Burns
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, United Kingdom.,Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Road, Headington, OX3 7LE, United Kingdom
| | | | - Fergus V Gleeson
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, United Kingdom.,Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Road, Headington, OX3 7LE, United Kingdom
| | - Daniel Bulte
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, United Kingdom.,Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Road, Headington, OX3 7LE, United Kingdom
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7
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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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8
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Collier GJ, Marshall H, Rao M, Stewart NJ, Capener D, Wild JM. Observation of cardiogenic flow oscillations in healthy subjects with hyperpolarized 3He MRI. J Appl Physiol (1985) 2015; 119:1007-14. [PMID: 26338461 PMCID: PMC4628994 DOI: 10.1152/japplphysiol.01068.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 08/31/2015] [Indexed: 11/22/2022] Open
Abstract
Recently, dynamic MRI of hyperpolarized (3)He during inhalation revealed an alternation of the image intensity between left and right lungs with a cardiac origin (Sun Y, Butler JP, Ferrigno M, Albert MS, Loring SH. Respir Physiol Neurobiol 185: 468-471, 2013). This effect is investigated further using dynamic and phase-contrast flow MRI with inhaled (3)He during slow inhalations (flow rate ∼100 ml/s) to elucidate airflow dynamics in the main lobes in six healthy subjects. The ventilation MR signal and gas inflow in the left lower lobe (LLL) of the lungs were found to oscillate clearly at the cardiac frequency in all subjects, whereas the MR signals in the other parts of the lungs had a similar oscillatory behavior but were smaller in magnitude and in anti-phase to the signal in the left lower lung. The airflow in the main bronchi showed periodic oscillations at the frequency of the cardiac cycle. In four of the subjects, backflows were observed for a short period of time of the cardiac cycle, demonstrating a pendelluft effect at the carina bifurcation between the left and right lungs. Additional (1)H structural MR images of the lung volume and synchronized ECG recording revealed that maximum inspiratory flow rates in the LLL of the lungs occurred during systole when the corresponding left lung volume increased, whereas the opposite effect was observed during diastole, with gas flow redirected to the other parts of the lung. In conclusion, cardiogenic flow oscillations have a significant effect on regional gas flow and distribution within the lungs.
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Affiliation(s)
- Guilhem J Collier
- 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
| | - Madhwesha Rao
- Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom
| | - Neil J Stewart
- Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom
| | - David Capener
- Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom
| | - Jim M Wild
- Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom
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9
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Sarracanie M, Grebenkov D, Sandeau J, Coulibaly S, Martin AR, Hill K, Pérez Sánchez JM, Fodil R, Martin L, Durand E, Caillibotte G, Isabey D, Darrasse L, Bittoun J, Maître X. Phase-contrast helium-3 MRI of aerosol deposition in human airways. NMR IN BIOMEDICINE 2015; 28:180-187. [PMID: 25476994 DOI: 10.1002/nbm.3238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 09/15/2014] [Accepted: 10/30/2014] [Indexed: 06/04/2023]
Abstract
One of the key challenges in the study of health-related aerosols is predicting and monitoring sites of particle deposition in the respiratory tract. The potential health risks of ambient exposure to environmental or workplace aerosols and the beneficial effects of medical aerosols are strongly influenced by the site of aerosol deposition along the respiratory tract. Nuclear medicine is the only current modality that combines quantification and regional localization of aerosol deposition, and this technique remains limited by its spatial and temporal resolutions and by patient exposure to radiation. Recent work in MRI has shed light on techniques to quantify micro-sized magnetic particles in living bodies by the measurement of associated static magnetic field variations. With regard to lung MRI, hyperpolarized helium-3 may be used as a tracer gas to compensate for the lack of MR signal in the airways, so as to allow assessment of pulmonary function and morphology. The extrathoracic region of the human respiratory system plays a critical role in determining aerosol deposition patterns, as it acts as a filter upstream from the lungs. In the present work, aerosol deposition in a mouth-throat phantom was measured using helium-3 MRI and compared with single-photon emission computed tomography. By providing high sensitivity with high spatial and temporal resolutions, phase-contrast helium-3 MRI offers new insights for the study of particle transport and deposition.
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Affiliation(s)
- Mathieu Sarracanie
- Imagerie par Résonance Magnétique Médicale et Multi-Modalités (UMR8081), IR4M, Université Paris-Sud, CNRS, Orsay, France; Department of Physics, Harvard University, Cambridge, MA, USA; MGH/A. A. Martinos Center for Biomedical Imaging, Boston, MA, USA
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Sul B, Wallqvist A, Morris MJ, Reifman J, Rakesh V. A computational study of the respiratory airflow characteristics in normal and obstructed human airways. Comput Biol Med 2014; 52:130-43. [DOI: 10.1016/j.compbiomed.2014.06.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/12/2014] [Accepted: 06/13/2014] [Indexed: 11/26/2022]
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Collier GJ, Wild JM. In vivo measurement of gas flow in human airways with hyperpolarized gas MRI and compressed sensing. Magn Reson Med 2014; 73:2255-61. [DOI: 10.1002/mrm.25348] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 06/09/2014] [Accepted: 06/12/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Guilhem J. Collier
- Unit of Academic Radiology; University of Sheffield; Sheffield United Kingdom
| | - Jim M. Wild
- Unit of Academic Radiology; University of Sheffield; Sheffield United Kingdom
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12
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Martin L, Maître X, de Rochefort L, Sarracanie M, Friese M, Hagot P, Durand E. Phase-contrast velocity mapping for highly diffusive fluids: optimal bipolar gradient pulse parameters for hyperpolarized helium-3. Magn Reson Med 2014; 72:1072-8. [PMID: 24407833 DOI: 10.1002/mrm.25005] [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: 06/11/2013] [Revised: 09/05/2013] [Accepted: 09/27/2013] [Indexed: 11/06/2022]
Abstract
PURPOSE In MR-velocity phase-contrast measurements, increasing the encoding bipolar gradient, i.e., decreasing the field of speed, usually improves measurement precision. However, in gases, fast diffusion during the bipolar gradient pulses may dramatically decrease the signal-to-noise ratio, thus degrading measurement precision. These two effects are contradictory. This work aims at determining the optimal sequence parameters to improve the velocity measurement precision. THEORY AND METHODS This work presents the theoretical optimization of bipolar gradient parameters (duration and amplitude) to improve velocity measurement precision. An analytical approximation is given as well as a numerical optimization. It is shown that the solution depends on the diffusion coefficient and T2 *. Experimental validation using hyperpolarized (3) He diluted in various buffer gases ((4) He, N2 , and SF6 ) is presented at 1.5 Tesla (T) in a straight pipe. RESULTS Excellent agreement was found with the theoretical results for prediction of optimal field of speed and good agreement was found for the precision in measured velocity, but for SF6 buffered gas. CONCLUSION The theoretical predictions were validated, providing a way to optimize velocity mapping in gases.
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13
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Minard KR, Kuprat AP, Kabilan S, Jacob RE, Einstein DR, Carson JP, Corley RA. Phase-contrast MRI and CFD modeling of apparent ³He gas flow in rat pulmonary airways. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 221:129-38. [PMID: 22771528 PMCID: PMC3448557 DOI: 10.1016/j.jmr.2012.05.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/10/2012] [Indexed: 05/11/2023]
Abstract
Phase-contrast (PC) magnetic resonance imaging (MRI) with hyperpolarized ³He is potentially useful for developing and testing patient-specific models of pulmonary airflow. One challenge, however, is that PC-MRI provides apparent values of local ³He velocity that not only depend on actual airflow but also on gas diffusion. This not only blurs laminar flow patterns in narrow airways but also introduces anomalous airflow structure that reflects gas-wall interactions. Here, both effects are predicted in a live rat using computational fluid dynamics (CFD), and for the first time, simulated patterns of apparent ³He gas velocity are compared with in vivo PC-MRI. Results show (1) that correlations (R²) between measured and simulated airflow patterns increase from 0.23 to 0.79 simply by accounting for apparent ³He transport, and (2) that remaining differences are mainly due to uncertain airway segmentation and partial volume effects stemming from relatively coarse MRI resolution. Higher-fidelity testing of pulmonary airflow predictions should therefore be possible with future imaging improvements.
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Affiliation(s)
- Kevin R Minard
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA.
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14
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Thompson RB, Finlay WH. Using MRI to Measure Aerosol Deposition. J Aerosol Med Pulm Drug Deliv 2012; 25:55-62. [DOI: 10.1089/jamp.2011.0897] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Richard B. Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Warren H. Finlay
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada
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15
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Abstract
Hyperpolarized gas magnetic resonance imaging has been explored extensively as a promising tool for the quantitative evaluation of regional pulmonary pathophysiology. This noninvasive technique is capable of providing both structural information down to the level of the alveolar microstructure and functional information, such as dynamic ventilation, intrapulmonary partial pressure of oxygen, and alveolar surface area. This study reviews the role of hyperpolarized 3-helium and 129-xenon magnetic resonance imaging in this research.
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17
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Minard KR, Jacob RE, Laicher G, Einstein DR, Kuprat AP, Corley RA. MR imaging of apparent 3He gas transport in narrow pipes and rodent airways. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 194:182-191. [PMID: 18667344 PMCID: PMC3613337 DOI: 10.1016/j.jmr.2008.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 06/30/2008] [Accepted: 07/01/2008] [Indexed: 05/25/2023]
Abstract
High sensitivity makes hyperpolarized (3)He an attractive signal source for visualizing gas flow with magnetic resonance (MR) imaging. Its rapid Brownian motion, however, can blur observed flow lamina and alter measured diffusion rates when excited nuclei traverse shear-induced velocity gradients during data acquisition. Here, both effects are described analytically, and predicted values for measured transport during laminar flow through a straight, 3.2-mm diameter pipe are validated using two-dimensional (2D) constant-time images of different binary gas mixtures. Results show explicitly how measured transport in narrow conduits is characterized by apparent values that depend on underlying gas dynamics and imaging time. In ventilated rats, this is found to obscure acquired airflow images. Nevertheless, flow splitting at airway branches is still evident and use of 3D vector flow mapping is shown to reveal surprising detail that highlights the correlation between gas dynamics and lung structure.
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Affiliation(s)
- Kevin R Minard
- Pacific Northwest National Laboratory, MSIN P7-58, Richland, WA 99352, USA.
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Mosbah K, Ruiz-Cabello J, Berthezène Y, Crémillieux Y. Aerosols and gaseous contrast agents for magnetic resonance imaging of the lung. CONTRAST MEDIA & MOLECULAR IMAGING 2008; 3:173-90. [DOI: 10.1002/cmmi.252] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Intrapulmonary 3He Gas Distribution Depending on Bolus Size and Temporal Bolus Placement. Invest Radiol 2008; 43:439-46. [DOI: 10.1097/rli.0b013e3181690111] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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de Rochefort L, Vial L, Fodil R, Maître X, Louis B, Isabey D, Caillibotte G, Thiriet M, Bittoun J, Durand E, Sbirlea-Apiou G. In vitro validation of computational fluid dynamic simulation in human proximal airways with hyperpolarized 3He magnetic resonance phase-contrast velocimetry. J Appl Physiol (1985) 2007; 102:2012-23. [PMID: 17289906 DOI: 10.1152/japplphysiol.01610.2005] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Computational fluid dynamics (CFD) and magnetic resonance (MR) gas velocimetry were concurrently performed to study airflow in the same model of human proximal airways. Realistic in vivo-based human airway geometry was segmented from thoracic computed tomography. The three-dimensional numerical description of the airways was used for both generation of a physical airway model using rapid prototyping and mesh generation for CFD simulations. Steady laminar inspiratory experiments (Reynolds number Re = 770) were performed and velocity maps down to the fourth airway generation were extracted from a new velocity mapping technique based on MR velocimetry using hyperpolarized (3)He gas. Full two-dimensional maps of the velocity vector were measured within a few seconds. Numerical simulations were carried out with the experimental flow conditions, and the two sets of data were compared between the two modalities. Flow distributions agreed within 3%. Main and secondary flow velocity intensities were similar, as were velocity convective patterns. This work demonstrates that experimental and numerical gas velocity data can be obtained and compared in the same complex airway geometry. Experiments validated the simulation platform that integrates patient-specific airway reconstruction process from in vivo thoracic scans and velocity field calculation with CFD, hence allowing the results of this numerical tool to be used with confidence in potential clinical applications for lung characterization. Finally, this combined numerical and experimental approach of flow assessment in realistic in vivo-based human airway geometries confirmed the strong dependence of airway flow patterns on local and global geometrical factors, which could contribute to gas mixing.
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Affiliation(s)
- Ludovic de Rochefort
- U2R2M, Unité de Recherche en Résonance Magnétique Médicale, CNRS, Univ Paris-Sud, Le Kremlin-Bicêtre, France
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