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Bdaiwi AS, Willmering MM, Wang H, Cleveland ZI. Diffusion weighted hyperpolarized 129 Xe MRI of the lung with 2D and 3D (FLORET) spiral. Magn Reson Med 2023; 89:1342-1356. [PMID: 36352793 PMCID: PMC9892235 DOI: 10.1002/mrm.29518] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 09/21/2022] [Accepted: 10/18/2022] [Indexed: 11/11/2022]
Abstract
PURPOSE To enable efficient hyperpolarized 129 Xe diffusion imaging using 2D and 3D (Fermat Looped, ORthogonally Encoded Trajectories, FLORET) spiral sequences and demonstrate that 129 Xe ADCs obtained using these sequences are comparable to those obtained using a conventional, 2D gradient-recalled echo (GRE) sequence. THEORY AND METHODS Diffusion-weighted 129 Xe MRI (b-values = 0, 7.5, 15 s/cm2 ) was performed in four healthy volunteers and one subject with lymphangioleiomyomatosis using slice-selective 2D-GRE (scan time = 15 s), slice-selective 2D-Spiral (4 s), and 3D-FLORET (16 s) sequences. Experimental SNRs from b-value = 0 images ( SNR 0 EX $$ SNR{0}_{EX} $$ ) and mean ADC values were compared across sequences. In two healthy subjects, a second b = 0 image was acquired using the 2D-Spiral sequence to map flip angle and correct RF-induced, hyperpolarized signal decay at the voxel level, thus improving regional ADC estimates. RESULTS Diffusion-weighted images from spiral sequences displayed image quality comparable to 2D-GRE and produced sufficient SNR 0 EX $$ SNR{0}_{EX} $$ (16.8 ± 3.8 for 2D-GRE, 21.2 ± 3.5 for 2D-Spiral, 20.4 ± 3.5 for FLORET) to accurately calculate ADC. Whole-lung means and SDs of ADC obtained via spiral were not significantly different (P > 0.54) from those obtained via 2D-GRE. Finally, 2D-Spiral images were corrected for signal decay, which resulted in a whole-lung mean ADC decrease of ˜15%, relative to uncorrected images. CONCLUSIONS Relative to GRE, efficient spiral sequences allow 129 Xe diffusion images to be acquired with isotropic lung coverage (3D), higher SNR $$ SNR $$ (2D and 3D), and three-fold faster (2D) within a single breath-hold. In turn, shortened breath-holds enable flip-angle mapping, and thus, allow RF-induced signal decay to be corrected, increasing ADC accuracy.
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Affiliation(s)
- Abdullah S. Bdaiwi
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229,Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH 45221
| | - Matthew M. Willmering
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Hui Wang
- Philips Healthcare, Cincinnati, OH 45229, USA
| | - Zackary I. Cleveland
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229,Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH 45221,Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45221,Imaging Research Center, Department of Radiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229,Corresponding Author: Zackary I. Cleveland, Center for Pulmonary Imaging Research, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., MLC-2021, Cincinnati, OH 45229, Telephone: (513) 803-7186, Facsimile: (513) 803-4783,
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2
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Zanette B, Munidasa S, Friedlander Y, Ratjen F, Santyr G. A 3D stack-of-spirals approach for rapid hyperpolarized 129 Xe ventilation mapping in pediatric cystic fibrosis lung disease. Magn Reson Med 2023; 89:1083-1091. [PMID: 36433705 DOI: 10.1002/mrm.29505] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/14/2022] [Accepted: 10/09/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE To demonstrate the feasibility of a rapid 3D stack-of-spirals (3D-SoS) imaging acquisition for hyperpolarized 129 Xe ventilation mapping in healthy pediatric participants and pediatric cystic fibrosis (CF) participants, in comparison to conventional Cartesian multislice (2D) gradient-recalled echo (GRE) imaging. METHODS The 2D-GRE and 3D-SoS acquisitions were performed in 13 pediatric participants (5 healthy, 8 CF) during separate breath-holds. Images from both sequences were compared on the basis of ventilation defect percent (VDP) and other measures of image similarity. The nadir of transient oxygen saturation (SpO2 ) decline due to xenon breath-holding was measured with pulse oximetry, and expressed as a percent change relative to baseline. RESULTS 129 Xe ventilation images were acquired in a breath-hold of 1.2-1.8 s with the 3D-SoS sequence, compared to 6.2-8.8 s for 2D-GRE. Mean ± SD VDP measures for 2D-GRE and 3D-SoS sequences were 5.02 ± 1.06% and 5.28 ± 1.08% in healthy participants, and 18.05 ± 8.26% and 18.75 ± 6.74% in CF participants, respectively. Across all participants, the intraclass correlation coefficient of VDP measures for both sequences was 0.98 (95% confidence interval: 0.94-0.99). The percent change in SpO2 was reduced to -2.1 ± 2.7% from -5.2 ± 3.5% with the shorter 3D-SoS breath-hold. CONCLUSION Hyperpolarized 129 Xe ventilation imaging with 3D-SoS yielded images approximately five times faster than conventional 2D-GRE, reducing SpO2 desaturation and improving tolerability of the xenon administration. Analysis of VDP and other measures of image similarity demonstrate excellent agreement between images obtained with both sequences. 3D-SoS holds significant potential for reducing the acquisition time of hyperpolarized 129 Xe MRI, and/or increasing spatial resolution while adhering to clinical breath-hold constraints.
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Affiliation(s)
- Brandon Zanette
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Samal Munidasa
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Yonni Friedlander
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Felix Ratjen
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Division of Respiratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Giles Santyr
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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Niedbalski PJ, Hall CS, Castro M, Eddy RL, Rayment JH, Svenningsen S, Parraga G, Zanette B, Santyr GE, Thomen RP, Stewart NJ, Collier GJ, Chan HF, Wild JM, Fain SB, Miller GW, Mata JF, Mugler JP, Driehuys B, Willmering MM, Cleveland ZI, Woods JC. Protocols for multi-site trials using hyperpolarized 129 Xe MRI for imaging of ventilation, alveolar-airspace size, and gas exchange: A position paper from the 129 Xe MRI clinical trials consortium. Magn Reson Med 2021; 86:2966-2986. [PMID: 34478584 DOI: 10.1002/mrm.28985] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/13/2021] [Accepted: 08/06/2021] [Indexed: 12/12/2022]
Abstract
Hyperpolarized (HP) 129 Xe MRI uniquely images pulmonary ventilation, gas exchange, and terminal airway morphology rapidly and safely, providing novel information not possible using conventional imaging modalities or pulmonary function tests. As such, there is mounting interest in expanding the use of biomarkers derived from HP 129 Xe MRI as outcome measures in multi-site clinical trials across a range of pulmonary disorders. Until recently, HP 129 Xe MRI techniques have been developed largely independently at a limited number of academic centers, without harmonizing acquisition strategies. To promote uniformity and adoption of HP 129 Xe MRI more widely in translational research, multi-site trials, and ultimately clinical practice, this position paper from the 129 Xe MRI Clinical Trials Consortium (https://cpir.cchmc.org/XeMRICTC) recommends standard protocols to harmonize methods for image acquisition in HP 129 Xe MRI. Recommendations are described for the most common HP gas MRI techniques-calibration, ventilation, alveolar-airspace size, and gas exchange-across MRI scanner manufacturers most used for this application. Moreover, recommendations are described for 129 Xe dose volumes and breath-hold standardization to further foster consistency of imaging studies. The intention is that sites with HP 129 Xe MRI capabilities can readily implement these methods to obtain consistent high-quality images that provide regional insight into lung structure and function. While this document represents consensus at a snapshot in time, a roadmap for technical developments is provided that will further increase image quality and efficiency. These standardized dosing and imaging protocols will facilitate the wider adoption of HP 129 Xe MRI for multi-site pulmonary research.
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Affiliation(s)
- Peter J Niedbalski
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Chase S Hall
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mario Castro
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Rachel L Eddy
- Centre for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.,Division of Respiratory Medicine, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jonathan H Rayment
- Division of Respiratory Medicine, Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sarah Svenningsen
- Firestone Institute for Respiratory Health, St Joseph's Healthcare, McMaster University, Hamilton, Ontario, Canada.,Department of Medicine, Division of Respirology, McMaster University, Hamilton, Ontario, Canada
| | - Grace Parraga
- Robarts Research Institute, Western University, London, Ontario, Canada
| | - Brandon Zanette
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Giles E Santyr
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Robert P Thomen
- Departments of Radiology and Bioengineering, University of Missouri, Columbia, Missouri, USA
| | - Neil J Stewart
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Guilhem J Collier
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Ho-Fung Chan
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Jim M Wild
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Sean B Fain
- Departments of Medical Physics, Radiology, and Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, USA
| | - G Wilson Miller
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Jaime F Mata
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - John P Mugler
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Bastiaan Driehuys
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Matthew M Willmering
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Zackary I Cleveland
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Departments of Pediatrics (Pulmonary Medicine) and Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Jason C Woods
- Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Departments of Pediatrics (Pulmonary Medicine) and Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
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Grynko V, Shepelytskyi Y, Li T, Hassan A, Granberg K, Albert MS. Hyperpolarized 129 Xe multi-slice imaging of the human brain using a 3D gradient echo pulse sequence. Magn Reson Med 2021; 86:3175-3181. [PMID: 34272774 DOI: 10.1002/mrm.28932] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 06/10/2021] [Accepted: 06/30/2021] [Indexed: 12/14/2022]
Abstract
PURPOSE To demonstrate the possibility of performing multi-slice in-vivo human brain MRI using hyperpolarized (HP) xenon-129 (129 Xe) in two different orientations and to calculate the signal-to-noise ratio (SNR). METHODS Two healthy female participants were imaged during a single breath-hold of HP 129 Xe using a Philips Achieva 3.0T MRI scanner (Philips, Andover, MA). Each HP 129 Xe multi-slice brain image was acquired during separate HP 129 Xe breath-holds using 3D gradient echo (GRE) imaging. The acquisition started 10 s after the inhalation of 1 L of HP 129 Xe. Overall, four sagittal and three axial images were acquired (seven imaging sessions per participant). The SNR was calculated for each slice in both orientations. RESULTS The first ever HP 129 Xe multi-slice images of the brain were acquired in axial and sagittal orientations. The HP 129 Xe signal distribution correlated well with the gray matter distribution. The highest SNR values were close in the axial and sagittal orientations (19.46 ± 3.25 and 18.76 ± 4.94, respectively). Additionally, anatomical features, such as the ventricles, were observed in both orientations. CONCLUSION The possibility of using multi-slice HP 129 Xe human brain magnetic resonance imaging was demonstrated for the first time. HP 129 Xe multi-slice MRI can be implemented for brain imaging to improve current diagnostic methods.
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Affiliation(s)
- Vira Grynko
- Chemistry and Materials Science Program, Lakehead University, Thunder Bay, Ontario, Canada.,Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
| | - Yurii Shepelytskyi
- Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada.,Chemistry Department, Lakehead University, Thunder Bay, Ontario, Canada
| | - Tao Li
- Chemistry Department, Lakehead University, Thunder Bay, Ontario, Canada
| | - Ayman Hassan
- Thunder Bay Regional Health Sciences Centre, Thunder Bay, Ontario, Canada.,Northern Ontario School of Medicine, Thunder Bay, Ontario, Canada
| | - Karl Granberg
- Thunder Bay Regional Health Sciences Centre, Thunder Bay, Ontario, Canada
| | - Mitchell S Albert
- Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada.,Chemistry Department, Lakehead University, Thunder Bay, Ontario, Canada.,Northern Ontario School of Medicine, Thunder Bay, Ontario, Canada
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Marshall H, Stewart NJ, Chan HF, Rao M, Norquay G, Wild JM. In vivo methods and applications of xenon-129 magnetic resonance. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 122:42-62. [PMID: 33632417 PMCID: PMC7933823 DOI: 10.1016/j.pnmrs.2020.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/26/2020] [Accepted: 11/29/2020] [Indexed: 05/28/2023]
Abstract
Hyperpolarised gas lung MRI using xenon-129 can provide detailed 3D images of the ventilated lung airspaces, and can be applied to quantify lung microstructure and detailed aspects of lung function such as gas exchange. It is sensitive to functional and structural changes in early lung disease and can be used in longitudinal studies of disease progression and therapy response. The ability of 129Xe to dissolve into the blood stream and its chemical shift sensitivity to its local environment allow monitoring of gas exchange in the lungs, perfusion of the brain and kidneys, and blood oxygenation. This article reviews the methods and applications of in vivo129Xe MR in humans, with a focus on the physics of polarisation by optical pumping, radiofrequency coil and pulse sequence design, and the in vivo applications of 129Xe MRI and MRS to examine lung ventilation, microstructure and gas exchange, blood oxygenation, and perfusion of the brain and kidneys.
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Affiliation(s)
- Helen Marshall
- POLARIS, Imaging Sciences, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Neil J Stewart
- POLARIS, Imaging Sciences, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Ho-Fung Chan
- POLARIS, Imaging Sciences, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Madhwesha Rao
- POLARIS, Imaging Sciences, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Graham Norquay
- POLARIS, Imaging Sciences, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Jim M Wild
- POLARIS, Imaging Sciences, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.
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6
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Somai V, Wright AJ, Fala M, Hesse F, Brindle KM. A multi spin echo pulse sequence with optimized excitation pulses and a 3D cone readout for hyperpolarized 13 C imaging. Magn Reson Med 2020; 84:1895-1908. [PMID: 32173908 PMCID: PMC8638674 DOI: 10.1002/mrm.28248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/23/2020] [Accepted: 02/14/2020] [Indexed: 12/25/2022]
Abstract
PURPOSE Imaging tumor metabolism in vivo using hyperpolarized [1-13 C]pyruvate is a promising technique for detecting disease, monitoring disease progression, and assessing treatment response. However, the transient nature of the hyperpolarization and its depletion following excitation limits the available time for imaging. We describe here a single-shot multi spin echo sequence, which improves on previously reported sequences, with a shorter readout time, isotropic point spread function (PSF), and better signal-to-noise ratio. METHODS The sequence uses numerically optimized spectrally selective excitation pulses set to the resonant frequencies of pyruvate and lactate and a hyperbolic secant adiabatic refocusing pulse, all applied in the absence of slice selection gradients. The excitation pulses were designed to be resistant to the effects of B0 and B1 field inhomogeneity. The gradient readout uses a 3D cone trajectory composed of 13 cones, all fully refocused and distributed among 7 spin echoes. The maximal gradient amplitude and slew rate were set to 4 G/cm and 20 G/cm/ms, respectively, to demonstrate the feasibility of clinical translation. RESULTS The pulse sequence gave an isotropic PSF of 2.8 mm. The excitation profiles of the optimized pulses closely matched simulations and a 46.10 ± 0.04% gain in image SNR was observed compared to a conventional Shinnar-Le Roux excitation pulse. The sequence was demonstrated with dynamic imaging of hyperpolarized [1-13 C]pyruvate and [1-13 C]lactate in vivo. CONCLUSION The pulse sequence was capable of dynamic imaging of hyperpolarized 13 C labeled metabolites in vivo with relatively high spatial and temporal resolution and immunity to system imperfections.
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Affiliation(s)
- Vencel Somai
- Cancer Research UK Cambridge InstituteUniversity of CambridgeCambridgeUnited Kingdom
- Department of Radiology, School of Clinical MedicineUniversity of CambridgeCambridgeUnited Kingdom
| | - Alan J. Wright
- Cancer Research UK Cambridge InstituteUniversity of CambridgeCambridgeUnited Kingdom
| | - Maria Fala
- Cancer Research UK Cambridge InstituteUniversity of CambridgeCambridgeUnited Kingdom
| | - Friederike Hesse
- Cancer Research UK Cambridge InstituteUniversity of CambridgeCambridgeUnited Kingdom
| | - Kevin M. Brindle
- Cancer Research UK Cambridge InstituteUniversity of CambridgeCambridgeUnited Kingdom
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
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7
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S. Fox M, V. Ouriadov A. High Resolution 3He Pulmonary MRI. Magn Reson Imaging 2019. [DOI: 10.5772/intechopen.84756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Woods JC, Conradi MS. 3He diffusion MRI in human lungs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 292:90-98. [PMID: 29705031 PMCID: PMC6386180 DOI: 10.1016/j.jmr.2018.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 03/05/2018] [Accepted: 04/11/2018] [Indexed: 06/08/2023]
Abstract
Hyperpolarized 3He gas allows the air spaces of the lungs to be imaged via MRI. Imaging of restricted diffusion is addressed here, which allows the microstructure of the lung to be characterized through the physical restrictions to gas diffusion presented by airway and alveolar walls in the lung. Measurements of the apparent diffusion coefficient (ADC) of 3He at time scales of milliseconds and seconds are compared; measurement of acinar airway sizes by determination of the microscopic anisotropy of diffusion is discussed. This is where Dr. JJH Ackerman's influence was greatest in aiding the formation of the Washington University 3He group, involving early a combination of physicists, radiologists, and surgeons, as the first applications of 3He ADC were to COPD and its destruction/modification of lung microstructure via emphysema. The sensitivity of the method to early COPD is demonstrated, as is its validation by direct comparison to histology. More recently the method has been used broadly in adult and pediatric obstructive lung diseases, from severe asthma to cystic fibrosis to bronchopulmonary dysplasia, a result of premature birth. These applications of the technique are discussed briefly.
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Affiliation(s)
- Jason C Woods
- Center for Pulmonary Imaging Research, Departments of Radiology and Pediatrics (Pulmonary Medicine), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, ML 5033, Cincinnati, OH 45229, USA; Department of Physics, Washington University, One Brookings Drive, CB 1105, St Louis, MO 63130, USA.
| | - Mark S Conradi
- ABQMR, Inc., 2301 Yale Blvd. SE, Suite C2, Albuquerque, NM 87106, USA; Department of Physics, Washington University, One Brookings Drive, CB 1105, St Louis, MO 63130, USA.
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Timm KN, Miller JJ, Henry JA, Tyler DJ. Cardiac applications of hyperpolarised magnetic resonance. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2018; 106-107:66-87. [PMID: 31047602 DOI: 10.1016/j.pnmrs.2018.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/14/2018] [Accepted: 05/29/2018] [Indexed: 05/05/2023]
Abstract
Cardiovascular disease is the leading cause of death world-wide. It is increasingly recognised that cardiac pathologies show, or may even be caused by, changes in metabolism, leading to impaired cardiac energetics. The heart turns over 15 times its own weight in ATP every day and thus relies heavily on the availability of substrates and on efficient oxidation to generate this ATP. A number of old and emerging drugs that target different aspects of metabolism are showing promising results with regard to improved cardiac outcomes in patients. A non-invasive imaging technique that could assess the role of different aspects of metabolism in heart disease, as well as measure changes in cardiac energetics due to treatment, would be valuable in the routine clinical care of cardiac patients. Hyperpolarised magnetic resonance spectroscopy and imaging have revolutionised metabolic imaging, allowing real-time metabolic flux assessment in vivo for the first time. In this review we summarise metabolism in the healthy and diseased heart, give an introduction to the hyperpolarisation technique, 'dynamic nuclear polarisation' (DNP), and review the preclinical studies that have thus far explored healthy cardiac metabolism and different models of human heart disease. We furthermore show what advances have been made to translate this technique into the clinic, what technical challenges still remain and what unmet clinical needs and unexplored metabolic substrates still need to be assessed by researchers in this exciting and fast-moving field.
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Affiliation(s)
- Kerstin N Timm
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK; Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK; Clarendon Laboratory, Department of Physics, University of Oxford, UK.
| | - John A Henry
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK; Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK.
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10
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Ouriadov AV, Santyr GE. High spatial resolution hyperpolarized3He MRI of the rodent lung using a single breath X-centric gradient-recalled echo approach. Magn Reson Med 2017; 78:2334-2341. [DOI: 10.1002/mrm.26602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 11/22/2016] [Accepted: 12/14/2016] [Indexed: 01/05/2023]
Affiliation(s)
- Alexei V. Ouriadov
- Imaging Research Laboratories, Robarts Research Institute; London Canada
- Department of Medical Biophysics; The University of Western Ontario; London Canada
| | - Giles E. Santyr
- Department of Medical Biophysics; University of Toronto; Toronto Canada
- Physiology & Experimental Medicine Program, Peter Gilgan Centre for Research and Learning, the Hospital for Sick Children; Toronto Canada
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11
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Chan HF, Stewart NJ, Parra-Robles J, Collier GJ, Wild JM. Whole lung morphometry with 3D multiple b-value hyperpolarized gas MRI and compressed sensing. Magn Reson Med 2016; 77:1916-1925. [PMID: 27283321 PMCID: PMC5412864 DOI: 10.1002/mrm.26279] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/15/2016] [Accepted: 04/26/2016] [Indexed: 01/05/2023]
Abstract
Purpose To demonstrate three‐dimensional (3D) multiple b‐value diffusion‐weighted (DW) MRI of hyperpolarized 3He gas for whole lung morphometry with compressed sensing (CS). Methods A fully‐sampled, two b‐value, 3D hyperpolarized 3He DW‐MRI dataset was acquired from the lungs of a healthy volunteer and retrospectively undersampled in the ky and kz phase‐encoding directions for CS simulations. Optimal k‐space undersampling patterns were determined by minimizing the mean absolute error between reconstructed and fully‐sampled 3He apparent diffusion coefficient (ADC) maps. Prospective three‐fold, undersampled, 3D multiple b‐value 3He DW‐MRI datasets were acquired from five healthy volunteers and one chronic obstructive pulmonary disease (COPD) patient, and the mean values of maps of ADC and mean alveolar dimension (LmD) were validated against two‐dimensional (2D) and 3D fully‐sampled 3He DW‐MRI experiments. Results Reconstructed undersampled datasets showed no visual artifacts and good preservation of the main image features and quantitative information. A good agreement between fully‐sampled and prospective undersampled datasets was found, with a mean difference of +3.4% and +5.1% observed in mean global ADC and LmD values, respectively. These differences were within the standard deviation range and consistent with values reported from healthy and COPD lungs. Conclusions Accelerated CS acquisition has facilitated 3D multiple b‐value 3He DW‐MRI scans in a single breath‐hold, enabling whole lung morphometry mapping. Magn Reson Med 77:1916–1925, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Ho-Fung Chan
- POLARIS, Academic Unit of Radiology, University of Sheffield, United Kingdom
| | - Neil J Stewart
- POLARIS, Academic Unit of Radiology, University of Sheffield, United Kingdom
| | - Juan Parra-Robles
- POLARIS, Academic Unit of Radiology, University of Sheffield, United Kingdom
| | - Guilhem J Collier
- POLARIS, Academic Unit of Radiology, University of Sheffield, United Kingdom
| | - Jim M Wild
- POLARIS, Academic Unit of Radiology, University of Sheffield, United Kingdom.,Insigneo, Institute for in silico medicine, Sheffield, United Kingdom
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12
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Miller JJ, Lau AZ, Teh I, Schneider JE, Kinchesh P, Smart S, Ball V, Sibson NR, Tyler DJ. Robust and high resolution hyperpolarized metabolic imaging of the rat heart at 7 T with 3D spectral-spatial EPI. Magn Reson Med 2016; 75:1515-24. [PMID: 25991606 PMCID: PMC4556070 DOI: 10.1002/mrm.25730] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/27/2015] [Accepted: 03/22/2015] [Indexed: 12/21/2022]
Abstract
PURPOSE Hyperpolarized metabolic imaging has the potential to revolutionize the diagnosis and management of diseases where metabolism is dysregulated, such as heart disease. We investigated the feasibility of imaging rodent myocardial metabolism at high resolution at 7 T. METHODS We present here a fly-back spectral-spatial radiofrequency pulse that sidestepped maximum gradient strength requirements and enabled high resolution metabolic imaging of the rodent myocardium. A 3D echo-planar imaging readout followed, with centric ordered z-phase encoding. The cardiac gated sequence was used to image metabolism in rodents whose metabolic state had been manipulated by being fasted, fed, or fed and given the pyruvate dehydrogenase kinase inhibitor dichloroacetate. RESULTS We imaged hyperpolarized metabolites with a spatial resolution of 2×2×3.8 mm(3) and a temporal resolution of 1.8 s in the rat heart at 7 T. Significant differences in myocardial pyruvate dehydrogenase flux were observed between the three groups of animals, concomitant with the known biochemistry. CONCLUSION The proposed sequence was able to image in vivo metabolism with excellent spatial resolution in the rat heart. The field of view enabled the simultaneous multi-organ acquisition of metabolic information from the rat, which is of great utility for preclinical research in cardiovascular disease. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance.
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Affiliation(s)
- Jack J. Miller
- Department of PhysicsClarendon LaboratoryUniversity of OxfordEnglandUK
- Department of PhysiologyAnatomy & GeneticsUniversity of OxfordEnglandUK
- Department of OncologyCancer Research UK and Medical Research Council Oxford Institute for Radiation OncologyUniversity of OxfordOxfordEnglandUK
| | - Angus Z. Lau
- Department of PhysiologyAnatomy & GeneticsUniversity of OxfordEnglandUK
- Division of Cardiovascular MedicineRadcliffe Department of MedicineUniversity of OxfordEnglandUK
| | - Irvin Teh
- Division of Cardiovascular MedicineRadcliffe Department of MedicineUniversity of OxfordEnglandUK
| | - Jürgen E. Schneider
- Division of Cardiovascular MedicineRadcliffe Department of MedicineUniversity of OxfordEnglandUK
| | - Paul Kinchesh
- Department of OncologyCancer Research UK and Medical Research Council Oxford Institute for Radiation OncologyUniversity of OxfordOxfordEnglandUK
| | - Sean Smart
- Department of OncologyCancer Research UK and Medical Research Council Oxford Institute for Radiation OncologyUniversity of OxfordOxfordEnglandUK
| | - Vicky Ball
- Department of PhysiologyAnatomy & GeneticsUniversity of OxfordEnglandUK
| | - Nicola R. Sibson
- Department of OncologyCancer Research UK and Medical Research Council Oxford Institute for Radiation OncologyUniversity of OxfordOxfordEnglandUK
| | - Damian J. Tyler
- Department of PhysiologyAnatomy & GeneticsUniversity of OxfordEnglandUK
- Division of Cardiovascular MedicineRadcliffe Department of MedicineUniversity of OxfordEnglandUK
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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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Kruger SJ, Nagle SK, Couch MJ, Ohno Y, Albert M, Fain SB. Functional imaging of the lungs with gas agents. J Magn Reson Imaging 2016; 43:295-315. [PMID: 26218920 PMCID: PMC4733870 DOI: 10.1002/jmri.25002] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/26/2015] [Indexed: 12/22/2022] Open
Abstract
This review focuses on the state-of-the-art of the three major classes of gas contrast agents used in magnetic resonance imaging (MRI)-hyperpolarized (HP) gas, molecular oxygen, and fluorinated gas--and their application to clinical pulmonary research. During the past several years there has been accelerated development of pulmonary MRI. This has been driven in part by concerns regarding ionizing radiation using multidetector computed tomography (CT). However, MRI also offers capabilities for fast multispectral and functional imaging using gas agents that are not technically feasible with CT. Recent improvements in gradient performance and radial acquisition methods using ultrashort echo time (UTE) have contributed to advances in these functional pulmonary MRI techniques. The relative strengths and weaknesses of the main functional imaging methods and gas agents are compared and applications to measures of ventilation, diffusion, and gas exchange are presented. Functional lung MRI methods using these gas agents are improving our understanding of a wide range of chronic lung diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis in both adults and children.
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Affiliation(s)
- Stanley J. Kruger
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
| | - Scott K. Nagle
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Pediatrics, University of Wisconsin – Madison, WI, U.S.A
| | - Marcus J. Couch
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Biotechnology Program, Lakehead University, Thunder Bay, ON, Canada
| | - Yoshiharu Ohno
- Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Mitchell Albert
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Department of Chemistry, Lakehead University, Thunder Bay, ON, Canada
| | - Sean B. Fain
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Biomedical Engineering, University of Wisconsin – Madison, WI, U.S.A
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15
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Tahir BA, Van Holsbeke C, Ireland RH, Swift AJ, Horn FC, Marshall H, Kenworthy JC, Parra-Robles J, Hartley R, Kay R, Brightling CE, De Backer J, Vos W, Wild JM. Comparison of CT-based Lobar Ventilation with 3He MR Imaging Ventilation Measurements. Radiology 2015; 278:585-92. [PMID: 26322908 DOI: 10.1148/radiol.2015142278] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To compare lobar lung ventilation computed from expiratory and inspiratory computed tomographic (CT) data with direct measurements of ventilation at hyperpolarized helium 3 ((3)He) magnetic resonance (MR) imaging by using same-breath hydrogen 1 ((1)H) MR imaging examinations to coregister the multimodality images. MATERIALS AND METHODS The study was approved by the national research ethics committee, and written patient consent was obtained. Thirty patients with asthma underwent breath-hold CT at total lung capacity and functional residual capacity. (3)He and (1)H MR images were acquired during the same breath hold at a lung volume of functional residual capacity plus 1 L. Lobar segmentations delineated by major fissures on both CT scans were used to calculate the percentage of ventilation per lobe from the change in inspiratory and expiratory lobar volumes. CT-based ventilation was compared with (3)He MR imaging ventilation by using diffeomorphic image registration of (1)H MR imaging to CT, which enabled indirect registration of (3)He MR imaging to CT. Statistical analysis was performed by using the Wilcoxon signed-rank test, Pearson correlation coefficient, and Bland-Altman analysis. RESULTS The mean ± standard deviation absolute difference between the CT and (3)He MR imaging percentage of ventilation volume in all lobes was 4.0% (right upper and right middle lobes, 5.4% ± 3.3; right lower lobe, 3.7% ± 3.9; left upper lobe, 2.8% ± 2.7; left lower lobe, 3.9% ± 2.6; Wilcoxon signed-rank test, P < .05). The Pearson correlation coefficient between the two techniques in all lobes was 0.65 (P < .001). Greater percentage of ventilation was seen in the upper lobes with (3)He MR imaging and in the lower lobes with CT. This was confirmed with Bland-Altman analysis, with 95% limits of agreement for right upper and middle lobes, -2.4, 12.7; right lower lobe, -11.7, 4.6; left upper lobe, -4.9, 8.7; and left lower lobe, -9.8, 2.8. CONCLUSION The percentage of regional ventilation per lobe calculated at CT was comparable to a direct measurement of lung ventilation at hyperpolarized (3)He MR imaging. This work provides evidence for the validity of the CT model, and same-breath (1)H MR imaging enables regional interpretation of (3)He ventilation MR imaging on the underlying lung anatomy at thin-section CT.
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Affiliation(s)
- Bilal A Tahir
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Cedric Van Holsbeke
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Rob H Ireland
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Andrew J Swift
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Felix C Horn
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Helen Marshall
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - John C Kenworthy
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Juan Parra-Robles
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Ruth Hartley
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Richard Kay
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Chris E Brightling
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Jan De Backer
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Wim Vos
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
| | - Jim M Wild
- From the Academic Units of Academic Radiology (B.A.T., A.J.S., F.C.H., H.M., J.C.K., J.P.R., J.M.W.) and Clinical Oncology (B.A.T., R.H.I.), University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, England; Fluidda, Kontich, Belgium (C.V.H., J.D.B., W.V.); Institute for Lung Health, University of Leicester, Leicester, England (R.H., C.E.B.); Novartis, Basel, Switzerland (R.K.); and INSIGNEO Institute of In-silico Medicine, Sheffield, England (A.J.S., J.M.W.)
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Stewart NJ, Norquay G, Griffiths PD, Wild JM. Feasibility of human lung ventilation imaging using highly polarized naturally abundant xenon and optimized three-dimensional steady-state free precession. Magn Reson Med 2015; 74:346-52. [DOI: 10.1002/mrm.25732] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/22/2015] [Accepted: 03/20/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Neil J. Stewart
- 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
| | - Paul D. Griffiths
- 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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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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18
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Leung G, Norquay G, Schulte RF, Wild JM. Radiofrequency pulse design for the selective excitation of dissolved 129Xe. Magn Reson Med 2014; 73:21-30. [PMID: 24395490 DOI: 10.1002/mrm.25089] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 10/30/2013] [Accepted: 11/27/2013] [Indexed: 12/25/2022]
Abstract
PURPOSE To optimize radiofrequency (RF) pulses for the selective excitation of dissolved phase (129)Xe that take into account the very short T2*, while simultaneously, minimally exciting the much larger gas signal. METHODS Numerical simulations of Shinnar le-Roux pulses and binomial coefficient composite-element pulses were performed and experimentally implemented on a 1.5 Tesla (T) clinical scanner. These were compared with pulses commonly used for short T2* imaging from the literature. The pulses were then experimentally tested in vivo with healthy volunteers inhaling hyperpolarized (129)Xe using nuclear MR spectroscopy on a 1.5T clinical scanner. RESULTS Standard RF excitation pulses inadvertently excite the gas compartment, or are long enough that the T2* of the dissolved compartment deteriorates the received signal. Amplitude modulated binomial composite pulses perform well being short and having high selectivity, however, deteriorate at high amplifier gain setting. Composite pulses using pulse width modulation provide the desired frequency response even in these nonlinear, high gain regimes. CONCLUSION Composite pulses provide a means of very narrow band frequency selectivity in a short duration pulse that is well suited to dissolved (129)Xe imaging. Pulse width modulation maintains the desired frequency response even in the presence of amplitude distortion.
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Affiliation(s)
- General Leung
- Unit of Academic Radiology, University of Sheffield, Sheffield, United Kingdom
| | - Graham Norquay
- 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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Horn FC, Deppe MH, Marshall H, Parra-Robles J, Wild JM. Quantification of regional fractional ventilation in human subjects by measurement of hyperpolarized 3He washout with 2D and 3D MRI. J Appl Physiol (1985) 2013; 116:129-39. [PMID: 24311749 DOI: 10.1152/japplphysiol.00378.2013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple-breath washout hyperpolarized (3)He MRI was used to calculate regional parametric images of fractional ventilation (r) as the ratio of fresh gas entering a volume unit to the total end inspiratory volume of the unit. Using a single dose of inhaled hyperpolarized gas and a total acquisition time of under 1 min, gas washout was measured by dynamic acquisitions during successive breaths with a fixed delay. A two-dimensional (2D) imaging protocol was investigated in four healthy subjects in the supine position, and in a second protocol the capability of extending the washout imaging to a three-dimensional (3D) acquisition covering the whole lungs was tested. During both protocols, subjects were breathing comfortably, only restricted by synchronization of breathing to the sequence timings. The 3D protocol was also successfully tested on one patient with cystic fibrosis. Mean r values from each volunteer were compared with global gas volume turnover, as calculated from flow measurement at the mouth divided by total lung volume (from MRI images), and a significant correlation (r = 0.74, P < 0.05) was found. The effects of gravity on R were investigated, and an average decrease in r of 5.5%/cm (Δr = 0.016 ± 0.006 cm(-1)) from posterior to anterior was found in the right lung. Intersubject reproducibility of r imaging with the 2D and 3D protocol was tested, and a significant correlation between repeated experiments was found in a pixel-by-pixel comparison. The proposed methods can be used to measure r on a regional basis.
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Affiliation(s)
- Felix C Horn
- Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom
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20
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Liszewski MC, Hersman FW, Altes TA, Ohno Y, Ciet P, Warfield SK, Lee EY. Magnetic resonance imaging of pediatric lung parenchyma, airways, vasculature, ventilation, and perfusion: state of the art. Radiol Clin North Am 2013; 51:555-82. [PMID: 23830786 DOI: 10.1016/j.rcl.2013.04.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Magnetic resonance (MR) imaging is a noninvasive imaging modality, particularly attractive for pediatric patients given its lack of ionizing radiation. Despite many advantages, the physical properties of the lung (inherent low signal-to-noise ratio, magnetic susceptibility differences at lung-air interfaces, and respiratory and cardiac motion) have posed technical challenges that have limited the use of MR imaging in the evaluation of thoracic disease in the past. However, recent advances in MR imaging techniques have overcome many of these challenges. This article discusses these advances in MR imaging techniques and their potential role in the evaluation of thoracic disorders in pediatric patients.
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Affiliation(s)
- Mark C Liszewski
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, 330 Longwood Avenue, Boston, MA 02115, USA
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Mugler JP, Altes TA. Hyperpolarized 129Xe MRI of the human lung. J Magn Reson Imaging 2013; 37:313-31. [PMID: 23355432 DOI: 10.1002/jmri.23844] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Accepted: 08/29/2012] [Indexed: 11/07/2022] Open
Abstract
By permitting direct visualization of the airspaces of the lung, magnetic resonance imaging (MRI) using hyperpolarized gases provides unique strategies for evaluating pulmonary structure and function. Although the vast majority of research in humans has been performed using hyperpolarized (3)He, recent contraction in the supply of (3)He and consequent increases in price have turned attention to the alternative agent, hyperpolarized (129) Xe. Compared to (3)He, (129)Xe yields reduced signal due to its smaller magnetic moment. Nonetheless, taking advantage of advances in gas-polarization technology, recent studies in humans using techniques for measuring ventilation, diffusion, and partial pressure of oxygen have demonstrated results for hyperpolarized (129)Xe comparable to those previously demonstrated using hyperpolarized (3)He. In addition, xenon has the advantage of readily dissolving in lung tissue and blood following inhalation, which makes hyperpolarized (129)Xe particularly attractive for exploring certain characteristics of lung function, such as gas exchange and uptake, which cannot be accessed using (3)He. Preliminary results from methods for imaging (129) Xe dissolved in the human lung suggest that these approaches will provide new opportunities for quantifying relationships among gas delivery, exchange, and transport, and thus show substantial potential to broaden our understanding of lung disease. Finally, recent changes in the commercial landscape of the hyperpolarized-gas field now make it possible for this innovative technology to move beyond the research laboratory.
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Affiliation(s)
- John P Mugler
- Center for In-vivo Hyperpolarized Gas MR Imaging, Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
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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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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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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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Marshall H, Ajraoui S, Deppe MH, Parra-Robles J, Wild JM. K-space filter deconvolution and flip angle self-calibration in 2D radial hyperpolarised 3He lung MRI. NMR IN BIOMEDICINE 2012; 25:389-399. [PMID: 21837646 DOI: 10.1002/nbm.1766] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/04/2011] [Accepted: 05/24/2011] [Indexed: 05/31/2023]
Abstract
In hyperpolarised (3)He lung MRI with constant flip angles, the transverse magnetisation decays with each RF excitation imposing a k-space filter on the acquired data. For radial data acquired in an angularly-sequential order, this filter causes streaking, angular shading and loss of spatial resolution in the images. The main aim of this work was to reduce the effects of the RF depletion k-space filter in radial acquisitions. Two approaches are presented; (i) retrospective deconvolution of the k-space filter for sequentially-acquired data and (ii) golden angle acquisition order. Radial trajectories sample the centre of k-space with every projection, thereby self-tracking signal decay. The inverse of the signal decay function was used to retrospectively deconvolve RF depolarisation k-space filter effects and the method was demonstrated in 2D radial imaging in phantoms and human lungs. A golden angle radial acquisition was shown to effectively suppress artefacts caused by the RF depletion k-space filter. In addition, the average flip angle per slice was calculated from the signal decay and the values were found to correspond with conventional flip angle maps, providing a means of flip angle self-calibration.
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Affiliation(s)
- Helen Marshall
- Unit of Academic Radiology, University of Sheffield, Floor C, Royal Hallamshire Hospital, Glossop Road, Sheffield, UK, S10 2JF.
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Xu X, Norquay G, Parnell SR, Deppe MH, Ajraoui S, Hashoian R, Marshall H, Griffiths PD, Parra-Robles J, Wild JM. Hyperpolarized129Xe gas lung MRI-SNR andT2*comparisons at 1.5 T and 3 T. Magn Reson Med 2012; 68:1900-4. [DOI: 10.1002/mrm.24190] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 12/29/2011] [Accepted: 01/05/2012] [Indexed: 12/24/2022]
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Schulte RF, Sacolick L, Deppe MH, Janich MA, Schwaiger M, Wild JM, Wiesinger F. Transmit gain calibration for nonproton MR using the Bloch-Siegert shift. NMR IN BIOMEDICINE 2011; 24:1068-1072. [PMID: 21387441 DOI: 10.1002/nbm.1657] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 11/11/2010] [Accepted: 12/02/2010] [Indexed: 05/30/2023]
Abstract
Transmit gain (B 1+) calibration is necessary for the adjustment of radiofrequency (RF) power levels to the desired flip angles. In proton MRI, this is generally an automated process before the actual scan without any user interaction. For other nuclei, it is usually time consuming and difficult, especially in the case of hyperpolarised MR. In the current work, transmit gain calibration was implemented on the basis of the Bloch-Siegert phase shift. From the same data, the centre frequency, line broadening and SNR could also be determined. The T(1) and B(0) insensitivity, and the wide range of B 1+ over which this technique is effective, make it well suited for nonproton applications. Examples are shown for hyperpolarised (13)C and (3)He applications.
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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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Wild JM, Ajraoui S, Deppe MH, Parnell SR, Marshall H, Parra-Robles J, Ireland RH. Synchronous acquisition of hyperpolarised 3He and 1H MR images of the lungs - maximising mutual anatomical and functional information. NMR IN BIOMEDICINE 2011; 24:130-134. [PMID: 20821726 DOI: 10.1002/nbm.1565] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 04/06/2010] [Accepted: 04/19/2010] [Indexed: 05/29/2023]
Abstract
The development of hybrid medical imaging scanners has allowed imaging with different detection modalities at the same time, providing different anatomical and functional information within the same physiological time course with the patient in the same position. Until now, the acquisition of proton MRI of lung anatomy and hyperpolarised gas MRI of lung function required separate breath-hold examinations, meaning that the images were not spatially registered or temporally synchronised. We demonstrate the spatially registered concurrent acquisition of lung images from two different nuclei in vivo. The temporal and spatial registration of these images is demonstrated by a high degree of mutual consistency that is impossible to achieve in separate scans and breath holds.
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Affiliation(s)
- Jim M Wild
- Unit of Academic Radiology, University of Sheffield, Sheffield, UK.
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Ireland RH, Din OS, Swinscoe JA, Woodhouse N, van Beek EJR, Wild JM, Hatton MQ. Detection of radiation-induced lung injury in non-small cell lung cancer patients using hyperpolarized helium-3 magnetic resonance imaging. Radiother Oncol 2010; 97:244-8. [PMID: 20724011 DOI: 10.1016/j.radonc.2010.07.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 07/01/2010] [Accepted: 07/13/2010] [Indexed: 10/19/2022]
Abstract
PURPOSE To compare hyperpolarized helium-3 magnetic resonance imaging ((3)He-MRI) acquired from non-small cell lung cancer (NSCLC) patients before and after external beam radiotherapy (EBRT). METHODS AND MATERIALS In an Ethics Committee-approved prospective study, five patients with histologically confirmed NSCLC gave written informed consent to undergo computed tomography (CT) and (3)He-MR ventilation imaging 1 week prior to and 3 months after radiotherapy. Images were registered to pre-treatment CT using anatomical landmark-based rigid registration to enable comparison. Emphysema was graded from examination of the CT. MRI-defined ventilation was calculated as the intersection of (3)He-MRI and CT lung volume as a percentage of the CT lung volume for the whole lung and regions of CT-defined pneumonitis. RESULTS On pre-treatment images, there was a significant correlation between the degree of CT-defined emphysema and (3)He-MRI whole lung ventilation (Spearman's rho=0.90, p=0.04). After radiation therapy, pneumonitis was evident on CT for 3/5 patients. For these cases, (3)He-MRI ventilation was significantly reduced within the regions of pneumonitis (pre: 94.1±2.2%, post: 73.7±4.7%; matched pairs Student's t-test, p=0.02, mean difference=20.4%, 95% confidence interval 6.3-34.6%). CONCLUSIONS This work demonstrates the feasibility of detecting ventilation changes between pre- and post-treatment using hyperpolarized helium-3 MRI for patients with NSCLC. Pre-treatment, the degree of emphysema and (3)He-MRI ventilation were correlated. For three cases of radiation pneumonitis, (3)He-MRI ventilation changes between pre- and post-treatment imaging were consistent with CT evidence of radiation-induced lung injury.
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Affiliation(s)
- Rob H Ireland
- Academic Unit of Clinical Oncology, University of Sheffield, UK.
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Ajraoui S, Lee KJ, Deppe MH, Parnell SR, Parra-Robles J, Wild JM. Compressed sensing in hyperpolarized3He Lung MRI. Magn Reson Med 2010; 63:1059-69. [PMID: 20373407 DOI: 10.1002/mrm.22302] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Salma Ajraoui
- Unit of Academic Radiology, University of Sheffield, Sheffield, UK
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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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Deppe MH, Teh K, Parra-Robles J, Lee KJ, Wild JM. Slice profile effects in 2D slice-selective MRI of hyperpolarized nuclei. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 202:180-189. [PMID: 19969495 DOI: 10.1016/j.jmr.2009.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 11/10/2009] [Accepted: 11/10/2009] [Indexed: 05/28/2023]
Abstract
This work explores slice profile effects in 2D slice-selective gradient-echo MRI of hyperpolarized nuclei. Two different sequences were investigated: a Spoiled Gradient Echo sequence with variable flip angle (SPGR-VFA) and a balanced Steady-State Free Precession (SSFP) sequence. It is shown that in SPGR-VFA the distribution of flip angles across the slice present in any realistically shaped radiofrequency (RF) pulse leads to large excess signal from the slice edges in later RF views, which results in an undesired non-constant total transverse magnetization, potentially exceeding the initial value by almost 300% for the last RF pulse. A method to reduce this unwanted effect is demonstrated, based on dynamic scaling of the slice selection gradient. SSFP sequences with small to moderate flip angles (<40 degrees ) are also shown to preserve the slice profile better than the most commonly used SPGR sequence with constant flip angle (SPGR-CFA). For higher flip angles, the slice profile in SSFP evolves in a manner similar to SPGR-CFA, with depletion of polarization in the center of the slice.
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Affiliation(s)
- Martin H Deppe
- Academic Radiology, University of Sheffield, C Floor Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, United Kingdom
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Woodhouse N, Wild JM, van Beek EJR, Hoggard N, Barker N, Taylor CJ. Assessment of hyperpolarized 3He lung MRI for regional evaluation of interventional therapy: a pilot study in pediatric cystic fibrosis. J Magn Reson Imaging 2010; 30:981-8. [PMID: 19856418 DOI: 10.1002/jmri.21949] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To determine whether regional changes in lung ventilation in a group of pediatric cystic fibrosis (CF) patients following a course of chest physiotherapy could be detected with (3)He MRI. MATERIALS AND METHODS The reproducibility of lung ventilation volume measurements obtained with (3)He lung magnetic resonance imaging (MRI) was established in a group of five children with CF age 6-15 years. The same methodology was then used to evaluate whether standard chest physiotherapy (percussion and drainage) had any immediate effect on regional ventilated lung volumes in a further group of nine age-matched CF children (5-15 years). RESULTS Global lung ventilation volumes remained the same within the limits of sensitivity derived from the reproducibility study; however, regional lung ventilation was observed to change in most patients after therapy. CONCLUSION (3)He MRI can be successfully used in children with CF, and has the sensitivity to detect regional quantitative changes in lung ventilation following chest physiotherapy.
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Affiliation(s)
- Neil Woodhouse
- Section of Academic Radiology, University of Sheffield, Sheffield, UK
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Ouriadov AV, Lam WW, Santyr GE. Rapid 3-D mapping of hyperpolarized 3He spin-lattice relaxation times using variable flip angle gradient echo imaging with application to alveolar oxygen partial pressure measurement in rat lungs. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2009; 22:309-18. [PMID: 19653021 DOI: 10.1007/s10334-009-0181-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 06/26/2009] [Accepted: 07/03/2009] [Indexed: 12/01/2022]
Abstract
OBJECTIVE The purpose of this work was to develop a rapid 3-D, variable flip angle (VFA) method for measurement of hyperpolarized (3)He T(1) which accounts for the effects of radiofrequency (RF) pulses without the need for additional flip angle information. MATERIALS AND METHODS The 3-D, VFA method was validated in vitro over a range of oxygen partial pressures ranging from 0.04 to 0.52 atm. The approach was also tested in vivo in five healthy rats as a function of increasing number of wash-out breaths. The T(1) accuracy of the VFA method in the presence of flip angle mis-setting and RF field non-uniformity was compared with the CFA method using simulations and experiments. RESULTS T(1) measurements were found to provide p(A)O(2) estimates, both in vitro and in vivo consistent with those predicted based on gas dilution and/or ventilation para- meters. For the RF pulse mis-setting (4%) and RF field non-uniformity (3%) used here, the VFA method provided a T(1) accuracy of better than 5% compared to 12% for the CFA method. CONCLUSION With sufficient RF field homogeneity (3%) and proper calibration (4%), the VFA approach can provide rapid and reliable 3-D T(1) mapping of hyperpolarized (3)He without the need for additional flip angle information.
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Affiliation(s)
- Alexei V Ouriadov
- Imaging Research Laboratories, Robarts Research Institute, P.O. Box 5015, 100 Perth Drive, London, ON, N6A 5K8, Canada.
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VAN BEEK EJR, TCHATALBACHEV V, WILD JM. Lung magnetic resonance imaging – an update. IMAGING 2008. [DOI: 10.1259/imaging/63202218] [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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Ireland RH, Woodhouse N, Hoggard N, Swinscoe JA, Foran BH, Hatton MQ, Wild JM. An image acquisition and registration strategy for the fusion of hyperpolarized helium-3 MRI and x-ray CT images of the lung. Phys Med Biol 2008; 53:6055-63. [PMID: 18843168 DOI: 10.1088/0031-9155/53/21/011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The purpose of this ethics committee approved prospective study was to evaluate an image acquisition and registration protocol for hyperpolarized helium-3 magnetic resonance imaging ((3)He-MRI) and x-ray computed tomography. Nine patients with non-small cell lung cancer (NSCLC) gave written informed consent to undergo a free-breathing CT, an inspiration breath-hold CT and a 3D ventilation (3)He-MRI in CT position using an elliptical birdcage radiofrequency (RF) body coil. (3)He-MRI to CT image fusion was performed using a rigid registration algorithm which was assessed by two observers using anatomical landmarks and a percentage volume overlap coefficient. Registration of (3)He-MRI to breath-hold CT was more accurate than to free-breathing CT; overlap 82.9 +/- 4.2% versus 59.8 +/- 9.0% (p < 0.001) and mean landmark error 0.75 +/- 0.24 cm versus 1.25 +/- 0.60 cm (p = 0.002). Image registration is significantly improved by using an imaging protocol that enables both (3)He-MRI and CT to be acquired with similar breath holds and body position through the use of a birdcage (3)He-MRI body RF coil and an inspiration breath-hold CT. Fusion of (3)He-MRI to CT may be useful for the assessment of patients with lung diseases.
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Affiliation(s)
- Rob H Ireland
- Academic Units of Radiology and Clinical Oncology, University of Sheffield, Sheffield, UK.
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De Zanche N, Chhina N, Teh K, Randell C, Pruessmann KP, Wild JM. Asymmetric quadrature split birdcage coil for hyperpolarized3He lung MRI at 1.5T. Magn Reson Med 2008; 60:431-8. [DOI: 10.1002/mrm.21664] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tsai LL, Mair RW, Rosen MS, Patz S, Walsworth RL. An open-access, very-low-field MRI system for posture-dependent 3He human lung imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 193:274-85. [PMID: 18550402 PMCID: PMC2572034 DOI: 10.1016/j.jmr.2008.05.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 05/20/2023]
Abstract
We describe the design and operation of an open-access, very-low-field, magnetic resonance imaging (MRI) system for in vivo hyperpolarized 3He imaging of the human lungs. This system permits the study of lung function in both horizontal and upright postures, a capability with important implications in pulmonary physiology and clinical medicine, including asthma and obesity. The imager uses a bi-planar B(0) coil design that produces an optimized 65 G (6.5 mT) magnetic field for 3He MRI at 210 kHz. Three sets of bi-planar coils produce the x, y, and z magnetic field gradients while providing a 79-cm inter-coil gap for the imaging subject. We use solenoidal Q-spoiled RF coils for operation at low frequencies, and are able to exploit insignificant sample loading to allow for pre-tuning/matching schemes and for accurate pre-calibration of flip angles. We obtain sufficient SNR to acquire 2D 3He images with up to 2.8mm resolution, and present initial 2D and 3D 3He images of human lungs in both supine and upright orientations. 1H MRI can also be performed for diagnostic and calibration reasons.
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Affiliation(s)
- L. L. Tsai
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02139
- Harvard Medical School, Boston, MA 02115
| | - R. W. Mair
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138
| | - M. S. Rosen
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138
- Department of Physics, Harvard University, Cambridge, MA 02138
| | - S. Patz
- Harvard Medical School, Boston, MA 02115
- Department of Radiology, Brigham and Women’s Hospital, Boston, MA 02115
| | - R. L. Walsworth
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138
- Department of Physics, Harvard University, Cambridge, MA 02138
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Tsai LL, Mair RW, Li CH, Rosen MS, Patz S, Walsworth RL. Posture-dependent human 3He lung imaging in an open-access MRI system: initial results. Acad Radiol 2008; 15:728-39. [PMID: 18486009 PMCID: PMC2474800 DOI: 10.1016/j.acra.2007.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Revised: 09/24/2007] [Accepted: 10/17/2007] [Indexed: 11/28/2022]
Abstract
RATIONALE AND OBJECTIVES The human lung and its functions are extremely sensitive to orientation and posture, and debate continues as to the role of gravity and the surrounding anatomy in determining lung function and heterogeneity of perfusion and ventilation. However, study of these effects is difficult. The conventional high-field magnets used for most hyperpolarized (3)He magnetic resonance imaging (MRI) of the human lung, and most other common radiologic imaging modalities including positron emission tomography and computed tomography, restrict subjects to lying horizontally, minimizing most gravitational effects. MATERIALS AND METHODS In this article, we review the motivation for posture-dependent studies of human lung function and present initial imaging results of human lungs in the supine and vertical body orientations using inhaled hyperpolarized (3)He gas and an open-access MRI instrument. The open geometry of this MRI system features a "walk-in" capability that permits subjects to be imaged in vertical and horizontal positions and potentially allows for complete rotation of the orientation of the imaging subject in a two-dimensional plane. RESULTS Initial results include two-dimensional lung images acquired with approximately 4 x 8 mm in-plane resolution and three-dimensional images with approximately 2-cm slice thickness. CONCLUSIONS Effects of posture variation are observed, including posture-related effects of the diaphragm and distension of the lungs while vertical.
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Affiliation(s)
- Leo L Tsai
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MS 59, Cambridge, MA 02138, USA
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Holmes JH, O'Halloran RL, Brodsky EK, Jung Y, Block WF, Fain SB. 3D hyperpolarized He-3 MRI of ventilation using a multi-echo projection acquisition. Magn Reson Med 2008; 59:1062-71. [PMID: 18429034 PMCID: PMC3001140 DOI: 10.1002/mrm.21437] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 09/12/2007] [Indexed: 11/07/2022]
Abstract
A method is presented for high-resolution 3D imaging of the whole lung using inhaled hyperpolarized (HP) He-3 MR with multiple half-echo radial trajectories that can accelerate imaging through undersampling. A multiple half-echo radial trajectory can be used to reduce the level of artifact for undersampled 3D projection reconstruction (PR) imaging by increasing the amount of data acquired per unit time for HP He-3 lung imaging. The point spread functions (PSFs) for breath-held He-3 MRI using multiple half-echo trajectories were evaluated using simulations to predict the effects of T(2)* and gas diffusion on image quality. Results from PSF simulations were consistent with imaging results in volunteer studies showing improved image quality with increasing number of echoes using up to 8 half-echoes. The 8-half-echo acquisition is shown to accommodate lost breath-holds as short as 6 sec using a retrospective reconstruction at reduced resolution and also to allow reduced breath-hold time compared with an equivalent Cartesian trajectory. Furthermore, preliminary results from a 3D dynamic inhalation-exhalation maneuver are demonstrated using the 8-half-echo trajectory. Results demonstrate the first high-resolution 3D PR imaging of ventilation and respiratory dynamics in humans using HP He-3 MR.
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Affiliation(s)
- James H Holmes
- Department of Medical Physics, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, USA
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Abstract
Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled multi-detector row CT allow for quantification of presence and distribution of parenchymal and airway pathology; xenon gas can be employed to assess regional ventilation of the lungs, and rapid bolus injections of iodinated contrast agent can provide a quantitative measure of regional parenchymal perfusion. Advances in MRI of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized gas imaging, which allow functional assessment, including ventilation/perfusion, microscopic air space measurements, and gas flow and transport dynamics.
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Affiliation(s)
- Edwin J R van Beek
- Department of Radiology, Carver College of Medicine, University of Iowa, C-751 GH, 200 Hawkins Drive, Iowa City, IA 52242-1077, USA.
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Driehuys B, Walker J, Pollaro J, Cofer GP, Mistry N, Schwartz D, Johnson GA. 3He MRI in mouse models of asthma. Magn Reson Med 2008; 58:893-900. [PMID: 17969115 DOI: 10.1002/mrm.21306] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the study of asthma, a vital role is played by mouse models, because knockout or transgenic methods can be used to alter disease pathways and identify therapeutic targets that affect lung function. Assessment of lung function in rodents by available methods is insensitive because these techniques lack regional specificity. A more sensitive method for evaluating lung function in human asthma patients uses hyperpolarized (HP) (3)He MRI before and after bronchoconstriction induced by methacholine (MCh). We now report the ability to perform such (3)He imaging of MCh response in mice, where voxels must be approximately 3000 times smaller than in humans and (3)He diffusion becomes an impediment to resolving the airways. We show three-dimensional (3D) images that reveal airway structure down to the fifth branching and visualize ventilation at a resolution of 125 x 125 x 1000 microm(3). Images of ovalbumin (OVA)-sensitized mice acquired after MCh show both airway closure and ventilation loss. To also observe the MCh response in naive mice, we developed a non-slice-selective 2D protocol with 187 x 187 microm(2) resolution that was fast enough to record the MCh response and recovery with 12-s temporal resolution. The extension of (3)He MRI to mouse models should make it a valuable translational tool in asthma research.
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Affiliation(s)
- Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Diaz S, Casselbrant I, Piitulainen E, Pettersson G, Magnusson P, Peterson B, Wollmer P, Leander P, Ekberg O, Akeson P. Hyperpolarized3He apparent diffusion coefficient MRI of the lung: Reproducibility and volume dependency in healthy volunteers and patients with emphysema. J Magn Reson Imaging 2008; 27:763-70. [DOI: 10.1002/jmri.21212] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Holmes JH, Korosec FR, Du J, O'Halloran RL, Sorkness RL, Grist TM, Kuhlman JE, Fain SB. Imaging of lung ventilation and respiratory dynamics in a single ventilation cycle using hyperpolarized He-3 MRI. J Magn Reson Imaging 2007; 26:630-6. [PMID: 17685417 DOI: 10.1002/jmri.20965] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To image respiratory dynamics and three-dimensional (3D) ventilation during inhalation, breath-hold, and exhalation for evaluation of obstructive lung disease using a single dose of hyperpolarized (HP) He-3 during MRI. MATERIALS AND METHODS A single 2D-3D projections inside Z encoding (PRIZE)-2D acquisition was performed that consisted of a rapid 2D radial acquisition phase during inhalation of the HP He-3, a 3D acquisition phase during a breath-hold interval, and finally the same 2D radial acquisition during a forced exhalation maneuver followed by tidal breathing. The 3D PRIZE acquisition was comprised of radial sampling in the coronal plane and Fourier encoding in the patient's anterior-posterior direction. Nine patients with mild/moderate to severe asthma were studied (two individuals were studied twice) using this technique. RESULTS Breath-hold and dynamic imaging results showed physiological abnormalities and were compared with results from standard spirometry, body plethysmography, and computed tomography (CT). Dynamic images depicted regions of differential gas clearance and trapping observed during and after forced exhalation that were corroborated as regions of air trapping on CT imaging. CONCLUSION The 2D-3D PRIZE-2D acquisition allowed for 3D depiction of ventilation during a breath-hold, as well as detection of gas trapping. Imaging results were confirmed with spirometry, body plethysmography, and CT.
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Affiliation(s)
- James H Holmes
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Wild JM, Woodhouse N, Teh K. Single-scan acquisition of registered hyperpolarized (3)He ventilation and ADC images using a hybrid 2D gradient-echo sequence. Magn Reson Med 2007; 57:1185-9. [PMID: 17534918 DOI: 10.1002/mrm.21235] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pulse sequences for hyperpolarized (3)He lung MRI that have made the most clinical impact to date are 1) those that supply regional apparent diffusion coefficient (ADC) measurements, which provide insight into early emphysematous destruction of the alveoli in the lungs, and 2) high-resolution ventilation images that provide regional indicators of airway obstruction in obstructive airway disease, such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). In this work a hybrid 2D ADC-ventilation sequence was used with low flip angles to acquire both sets of data in the same breath-hold. The performance of the sequence was investigated in vivo in a healthy subject and a subject with mild emphysema, and compared with conventional 2D gradient-echo (GRE) (3)He ventilation and ADC imaging sequences. Acquisition of the ADC and ventilation images in one breath-hold provides ventilation images with equal or better SNR (approximately 20) and the same spatial resolution (3.75 mm x 3.3 mm in plane) with simultaneous accurate, high-resolution ADC images. The hybrid sequence offers a means of conserving gas by using two-thirds of the (3)He gas needed for separate ADC and ventilation exams, and saves the subject from having to perform an extra breath-hold. The data are inherently spatially and temporally registered, allowing quantitative cross-correlation between high-spatial-resolution ADC and ventilation data.
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Affiliation(s)
- Jim M Wild
- Unit of Academic Radiology, University of Sheffield, Sheffield, UK.
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Fain SB, Korosec FR, Holmes JH, O'Halloran R, Sorkness RL, Grist TM. Functional lung imaging using hyperpolarized gas MRI. J Magn Reson Imaging 2007; 25:910-23. [PMID: 17410561 DOI: 10.1002/jmri.20876] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The noninvasive assessment of lung function using imaging is increasingly of interest for the study of lung diseases, including chronic obstructive pulmonary disease (COPD) and asthma. Hyperpolarized gas MRI (HP MRI) has demonstrated the ability to detect changes in ventilation, perfusion, and lung microstructure that appear to be associated with both normal lung development and disease progression. The physical characteristics of HP gases and their application to MRI are presented with an emphasis on current applications. Clinical investigations using HP MRI to study asthma, COPD, cystic fibrosis, pediatric chronic lung disease, and lung transplant are reviewed. Recent advances in polarization, pulse sequence development for imaging with Xe-129, and prototype low magnetic field systems dedicated to lung imaging are highlighted as areas of future development for this rapidly evolving technology.
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Affiliation(s)
- Sean B Fain
- Department of Medical Physics, University of Wisconsin, Madison, WI 53792, USA.
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49
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Ireland RH, Bragg CM, McJury M, Woodhouse N, Fichele S, van Beek EJR, Wild JM, Hatton MQ. Feasibility of image registration and intensity-modulated radiotherapy planning with hyperpolarized helium-3 magnetic resonance imaging for non-small-cell lung cancer. Int J Radiat Oncol Biol Phys 2007; 68:273-81. [PMID: 17448880 PMCID: PMC2713782 DOI: 10.1016/j.ijrobp.2006.12.068] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 12/18/2006] [Accepted: 12/19/2006] [Indexed: 12/25/2022]
Abstract
Purpose: To demonstrate the feasibility of registering hyperpolarized helium-3 magnetic resonance images (3He-MRI) to X-ray computed tomography (CT) for functionally weighted intensity-modulated radiotherapy (IMRT) planning. Methods and Materials: Six patients with non–small-cell lung cancer underwent 3He ventilation MRI, which was fused with radiotherapy planning CT using rigid registration. Registration accuracy was assessed using an overlap coefficient, calculated as the proportion of the segmented 3He-MR volume (VMRI) that intersects the segmented CT lung volume expressed as a percentage of VMRI. For each patient, an IMRT plan that minimized the volume of total lung receiving a dose ≥20 Gy (V20) was compared with a plan that minimized the V20 to well-ventilated lung defined by the registered 3He-MRI. Results: The 3He-MRI and CT were registered with sufficient accuracy to enable functionally guided IMRT planning (median overlap, 89%; range, 72–97%). In comparison with the total lung IMRT plans, IMRT constrained with 3He-MRI reduced the V20 not only for the well-ventilated lung (median reduction, 3.1%; range, 0.4–5.1%; p = 0.028) but also for the total lung volume (median reduction, 1.6%; range, 0.2–3.7%; p = 0.028). Conclusions: Statistically significant improvements to IMRT plans are possible using functional information provided by 3He-MRI that has been registered to radiotherapy planning CT.
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Affiliation(s)
- Rob H Ireland
- Academic Unit of Radiology, University of Sheffield, Sheffield, United Kingdom.
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Teh K, de Zanche N, Wild JM. Radiation-damping effects in a birdcage resonator with hyperpolarised 3He gas NMR at 1.5 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 185:164-72. [PMID: 17174581 DOI: 10.1016/j.jmr.2006.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 11/09/2006] [Accepted: 11/15/2006] [Indexed: 05/13/2023]
Abstract
The presence and diagnosis of radiation damping could have major implications in NMR experiments with hyperpolarised gases, where accurate knowledge of the flip angle is imperative. In this work radiation damping was observed and investigated in a low-pass birdcage resonator (Q=250) with samples of hyperpolarised 3He at 1.5 T. With an initially highly polarised (P=38%) sample of 3He in a spherical cell, the observed FID had a distorted line shape with a spectral line width that was three times that of the same sample in a virtually depolarised state (1 Hz line width for P<1%). Moreover a linear relation between the sample's magnetisation (M0) and the line width of the spectrum was observed which is indicative of radiation damping. With highly polarised samples, significant radiation damping was observed and the effect was a lower than expected rate of depletion of M0 in RF flip angle calibration experiments, which led to significant underestimate of the RF flip angle. To our knowledge this is the first report of radiation damping in a birdcage resonator with samples hyperpolarised or otherwise. Experimental observation of radiation damping could be used as means of measuring coil efficiency as an alternative to the geometrical filling factor (eta) the definition of which is open to question for a birdcage resonator. Estimates of the birdcage filling factor from the measured damping time constants (eta(RD)=0.4%) are compared to those derived from electromagnetic energy ratios (eta(E)=1.6%) and metallic sphere frequency shift methods (eta(fs)=1.4%). These figures are much lower than the simple volume geometrical upper limit of eta(v)=3.7% derived from the ratio of cell volume to total coil volume (shield included). The physical explanation for this shortfall is that the bulk of the magnetic energy stored in the birdcage is spatially distributed predominantly between the rungs and the shield, and not in the coil centre where the sample is placed and where the B1+ field has its highest spatial homogeneity.
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Affiliation(s)
- Kevin Teh
- Unit of Academic Radiology, University of Sheffield, Sheffield, England S10 2JF, UK
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