1
|
Perron S, Ouriadov A. Hyperpolarized 129Xe MRI at low field: Current status and future directions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 348:107387. [PMID: 36731353 DOI: 10.1016/j.jmr.2023.107387] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/07/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Magnetic Resonance Imaging (MRI) is dictated by the magnetization of the sample, and is thus a low-sensitivity imaging method. Inhalation of hyperpolarized (HP) noble gases, such as helium-3 and xenon-129, is a non-invasive, radiation-risk free imaging technique permitting high resolution imaging of the lungs and pulmonary functions, such as the lung microstructure, diffusion, perfusion, gas exchange, and dynamic ventilation. Instead of increasing the magnetic field strength, the higher spin polarization achievable from this method results in significantly higher net MR signal independent of tissue/water concentration. Moreover, the significantly longer apparent transverse relaxation time T2* of these HP gases at low magnetic field strengths results in fewer necessary radiofrequency (RF) pulses, permitting larger flip angles; this allows for high-sensitivity imaging of in vivo animal and human lungs at conventionally low (<0.5 T) field strengths and suggests that the low field regime is optimal for pulmonary MRI using hyperpolarized gases. In this review, theory on the common spin-exchange optical-pumping method of hyperpolarization and the field dependence of the MR signal of HP gases are presented, in the context of human lung imaging. The current state-of-the-art is explored, with emphasis on both MRI hardware (low field scanners, RF coils, and polarizers) and image acquisition techniques (pulse sequences) advancements. Common challenges surrounding imaging of HP gases and possible solutions are discussed, and the future of low field hyperpolarized gas MRI is posed as being a clinically-accessible and versatile imaging method, circumventing the siting restrictions of conventional high field scanners and bringing point-of-care pulmonary imaging to global facilities.
Collapse
Affiliation(s)
- Samuel Perron
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada.
| | - Alexei Ouriadov
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada; School of Biomedical Engineering, Faculty of Engineering, The University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
2
|
Zhou Q, Li H, Rao Q, Zhang M, Zhao X, Shen L, Fang Y, Li H, Liu X, Xiao S, Shi L, Han Y, Ye C, Zhou X. Assessment of pulmonary morphometry using hyperpolarized 129 Xe diffusion-weighted MRI with variable-sampling-ratio compressed sensing patterns. Med Phys 2023; 50:867-878. [PMID: 36196039 DOI: 10.1002/mp.16018] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 08/26/2022] [Accepted: 09/24/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Hyperpolarized (HP) 129 Xe multiple b-values diffusion-weighted magnetic resonance imaging (DW-MRI) has been widely used for quantifying pulmonary microstructural morphometry. However, the technique requires long acquisition times, making it hard to apply in patients with severe pulmonary diseases, who cannot sustain long breath holds. PURPOSE To develop and evaluate the technique of variable-sampling-ratio compressed sensing (VCS) patterns for accelerating HP 129 Xe multiple b-values DW-MRI in humans. METHODS Optimal variable sampling ratios and corresponding k-space undersampling patterns for each b-value were obtained by retrospective simulations based on the fully sampled (FS) DW-MRI dataset acquired from six young healthy volunteers. Then, the FS datasets were retrospectively undersampled using both VCS patterns and conventional compressed sensing (CS) pattern with a similar average acceleration factor. The quality of reconstructed images with retrospective VCS (rVCS) and CS (rCS) datasets were quantified using mean absolute error (MAE) and structural similarity (SSIM). Pulmonary morphometric parameters were also evaluated between rVCS and FS datasets. In addition, prospective VCS multiple b-values 129 Xe DW-MRI datasets were acquired from 14 cigarette smokers and 13 age-matched healthy volunteers. The differences of lung morphological parameters obtained with the proposed method were compared between the groups using independent samples t-test. Pearson correlation coefficient was also utilized for evaluating the correlation of the pulmonary physiological parameters obtained with VCS DW-MRI and pulmonary function tests. RESULTS Lower MAE and higher SSIM values were found in the reconstructed images with rVCS measurement when compared to those using conventional rCS measurement. The details and quality of the images obtained with rVCS and FS measurements were found to be comparable. The mean values of the morphological parameters derived from rVCS and FS datasets showed no significant differences (p > 0.05), and the mean differences of measured acinar duct radius, mean linear intercept, surface-to-volume ratio, and apparent diffusion coefficient with cylinder model were -0.87%, -2.42%, 2.04%, and -0.50%, respectively. By using the VCS technique, significant differences were delineated between the pulmonary morphometric parameters of healthy volunteers and cigarette smokers (p < 0.001), while the acquisition time was reduced by four times. CONCLUSION A fourfold reduction in acquisition time was achieved using the proposed VCS method while preserving good image quality. Our preliminary results demonstrated that the proposed method can be used for evaluating pulmonary injuries caused by cigarette smoking and may prove to be helpful in diagnosing lung diseases in clinical practice.
Collapse
Affiliation(s)
- Qian Zhou
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Haidong Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qiuchen Rao
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China
| | - Ming Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiuchao Zhao
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Luyang Shen
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China
| | - Yuan Fang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China
| | - Hongchuang Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoling Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Sa Xiao
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lei Shi
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yeqing Han
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Chaohui Ye
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xin Zhou
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
3
|
Gas exchange and ventilation imaging of healthy and COPD subjects using hyperpolarized xenon-129 MRI and a 3D alveolar gas-exchange model. Eur Radiol 2022; 33:3322-3331. [PMID: 36547671 DOI: 10.1007/s00330-022-09343-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 11/24/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022]
Abstract
OBJECTIVES To investigate the utility of hyperpolarized xenon-129 (HPX) gas-exchange magnetic resonance imaging (MRI) and modeling in a chronic obstructive pulmonary disease (COPD) cohort in comparison to a minimal CT-diagnosed emphysema (MCTE) cohort and a healthy cohort. METHODS A total of 25 subjects were involved in this study including COPD (n = 8), MCTE (n = 3), and healthy (n = 14) subjects. The COPD subjects were scanned using HPX ventilation, gas-exchange MRI, and volumetric CT. The healthy subjects were scanned using the same HPX gas-exchange MRI protocol with 9 of them scanned twice, 3 weeks apart. The coefficient of variation (CV) was used to quantify image heterogeneities. A three-dimensional computational fluid dynamic (CFD) model of gas exchange was used to derive functional volumes of pulmonary tissue, capillaries, and veins. RESULTS The CVs of gas distributions in the images showed that there was a statistically significant difference between the COPD and healthy subjects (p < 0.0001). The functional volumes of pulmonary tissue, capillaries, and veins were significantly lower in the subjects with COPD than in the healthy subjects (p < 0.001). The functional volume of pulmonary tissue was found to be (i) statistically different between the healthy and MCTE groups (p = 0.02) and (ii) dependent on the age of the subjects in the healthy group (p = 0.0008) while their CVs (p = 0.13) were not. CONCLUSION The novel HPX gas-exchange MRI and CFD model distinguished the healthy cohort from the MCTE and COPD cohorts. The proposed technique also showed that the functional volume of pulmonary tissue decreases with aging in the healthy group. KEY POINTS • The ventilation and gas-exchange imaging with hyperpolarized xenon-129 MRI has enabled the identification of gas-exchange variation between COPD and healthy groups. • This novel technique was promising to be sensitive to minimal CT-diagnosed emphysema and age-related changes in gas-exchange parameter in a small pilot cohort.
Collapse
|
4
|
Preclinical MRI Using Hyperpolarized 129Xe. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238338. [PMID: 36500430 PMCID: PMC9738892 DOI: 10.3390/molecules27238338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 12/05/2022]
Abstract
Although critical for development of novel therapies, understanding altered lung function in disease models is challenging because the transport and diffusion of gases over short distances, on which proper function relies, is not readily visualized. In this review we summarize progress introducing hyperpolarized 129Xe imaging as a method to follow these processes in vivo. The work is organized in sections highlighting methods to observe the gas replacement effects of breathing (Gas Dynamics during the Breathing Cycle) and gas diffusion throughout the parenchymal airspaces (3). We then describe the spectral signatures indicative of gas dissolution and uptake (4), and how these features can be used to follow the gas as it enters the tissue and capillary bed, is taken up by hemoglobin in the red blood cells (5), re-enters the gas phase prior to exhalation (6), or is carried via the vasculature to other organs and body structures (7). We conclude with a discussion of practical imaging and spectroscopy techniques that deliver quantifiable metrics despite the small size, rapid motion and decay of signal and coherence characteristic of the magnetically inhomogeneous lung in preclinical models (8).
Collapse
|
5
|
Friedlander Y, Zanette B, Lindenmaier A, Li D, Kadlecek S, Santyr G, Kassner A. Hyperpolarized 129 Xe MRI of the rat brain with chemical shift saturation recovery and spiral-IDEAL readout. Magn Reson Med 2021; 87:1971-1979. [PMID: 34841605 DOI: 10.1002/mrm.29105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 01/03/2023]
Abstract
PURPOSE To demonstrate the feasibility of 129 Xe chemical shift saturation recovery (CSSR) combined with spiral-IDEAL imaging for simultaneous measurement of the time-course of red blood cell (RBC) and brain tissue signals in the rat brain. METHODS Images of both the RBC and brain tissue 129 Xe signals from the brains of five rats were obtained using interleaved spiral-IDEAL imaging following chemical shift saturation pulses applied at multiple CSSR delay times, τ. A linear fit of the signals to τ was used to calculate the slope of the signal for both RBC and brain tissue compartments on a voxel-by-voxel basis. Gas transfer was evaluated by measuring the ratio of the whole brain tissue-to-RBC signal intensities as a function of τ. To investigate the relationship between the CSSR images and gas transfer in the brain, the experiments were repeated during hypercapnic ventilation. RESULTS Hypercapnia, affected the ratio of the tissue-to-RBC signal intensity (p = 0.026), consistent with an increase in gas transfer. CONCLUSION CSSR with spiral-IDEAL imaging is feasible for acquisition of 129 Xe RBC and brain tissue time-course images in the rat brain. Differences in the time-course of the signal intensity ratios are consistent with gas transfer changes expected under hypercapnic conditions.
Collapse
Affiliation(s)
- Yonni Friedlander
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Brandon Zanette
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Andras Lindenmaier
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Daniel Li
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Giles Santyr
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Andrea Kassner
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
6
|
Fliss JD, Zanette B, Friedlander Y, Sadanand S, Lindenmaier AA, Stirrat E, Li D, Post M, Jankov RP, Santyr G. Hyperpolarized 129Xe magnetic resonance spectroscopy in a rat model of bronchopulmonary dysplasia. Am J Physiol Lung Cell Mol Physiol 2021; 321:L507-L517. [PMID: 34189953 DOI: 10.1152/ajplung.00612.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Premature infants often require mechanical ventilation and oxygen therapy, which can result in bronchopulmonary dysplasia (BPD), characterized by developmental arrest and impaired lung function. Conventional clinical methods for assessing the prenatal lung are not adequate for the detection and assessment of long-term health risks in infants with BPD, highlighting the need for a noninvasive tool for the characterization of lung microstructure and function. Theoretical diffusion models, like the model of xenon exchange (MOXE), interrogate alveolar gas exchange by predicting the uptake of inert hyperpolarized (HP) 129Xe gas measured with HP 129Xe magnetic resonance spectroscopy (MRS). To investigate HP 129Xe MRS as a tool for noninvasive characterization of pulmonary microstructural and functional changes in vivo, HP 129Xe gas exchange data were acquired in an oxygen exposure rat model of BPD that recapitulates the fewer and larger distal airways and pulmonary vascular stunting characteristics of BPD. Gas exchange parameters from MOXE, including airspace mean chord length (Lm), apparent hematocrit in the pulmonary capillaries (HCT), and pulmonary capillary transit time (tx), were compared with airspace mean axis length and area density (MAL and ρA) and percentage area of tissue and air (PTA and PAA) from histology. Lm was significantly larger in the exposed rats (P = 0.003) and correlated with MAL, ρA, PTA, and PAA (0.59<|ρ|<0.66 and P < 0.05). Observed increase in HCT (P = 0.012) and changes in tx are also discussed. These findings support the use of HP 129Xe MRS for detecting fewer, enlarged distal airways in this rat model of BPD, and potentially in humans.
Collapse
Affiliation(s)
- Jordan D Fliss
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Brandon Zanette
- Translational Medicine Program, The Hospital for Sick Children, 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
| | - Siddharth Sadanand
- Department of Biomedical Physics, Ryerson University, Toronto, Ontario, Canada
| | - Andras A Lindenmaier
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Elaine Stirrat
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Daniel Li
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Martin Post
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Robert P Jankov
- Molecular Biomedicine Program, Children's Hospital of Eastern Ontario Research Institute, Ottawa, 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
| |
Collapse
|
7
|
Friedlander Y, Zanette B, Lindenmaier AA, Fliss J, Li D, Emami K, Jankov RP, Kassner A, Santyr G. Effect of inhaled oxygen concentration on 129 Xe chemical shift of red blood cells in rat lungs. Magn Reson Med 2021; 86:1187-1193. [PMID: 33837550 DOI: 10.1002/mrm.28801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/22/2021] [Accepted: 03/21/2021] [Indexed: 11/08/2022]
Abstract
PURPOSE To investigate the dependence of dissolved 129 Xe chemical shift on the fraction of inhaled oxygen, Fi O2 , in the lungs of healthy rats. METHODS The chemical shifts of 129 Xe dissolved in red blood cells, δRBC , and blood plasma and/or tissue, δPlasma , were measured using MRS in 12 Sprague Dawley rats mechanically ventilated at Fi O2 values of 0.14, 0.19, and 0.22. Regional effects on the chemical shifts were controlled using a chemical shift saturation recovery sequence with a fixed delay time. MRS was also performed at an Fi CO2 value of 0.085 to investigate the potential effect of the vascular response on δRBC and δPlasma . RESULTS δRBC increased with decreasing Fi O2 (P = .0002), and δPlasma showed no dependence on Fi O2 (P = .23). δRBC at Fi CO2 = 0 (210.7 ppm ± 0.1) and at Fi CO2 = 0.085 (210.6 ppm ± 0.2) were not significantly different (P = .67). δPlasma at Fi CO2 = 0 (196.9 ppm ± 0.3) and at Fi CO2 = 0.085 (197.0 ppm ± 0.1) were also not significantly different (P = .81). CONCLUSION Rat lung δRBC showed an inverse relationship to Fi O2 , opposite to the relationship previously demonstrated for in vitro human blood. Rat lung δRBC did not depend on Fi CO2 .
Collapse
Affiliation(s)
- Yonni Friedlander
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Brandon Zanette
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Andras A Lindenmaier
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Jordan Fliss
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Daniel Li
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | | | - Robert P Jankov
- Molecular Biomedicine Program, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Andrea Kassner
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Giles Santyr
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
8
|
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.
Collapse
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.
| |
Collapse
|
9
|
Ruppert K, Amzajerdian F, Xin Y, Hamedani H, Loza L, Achekzai T, Duncan IF, Profka H, Qian Y, Pourfathi M, Kadlecek S, Rizi RR. Investigating biases in the measurement of apparent alveolar septal wall thickness with hyperpolarized 129Xe MRI. Magn Reson Med 2020; 84:3027-3039. [PMID: 32557808 DOI: 10.1002/mrm.28329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/03/2020] [Accepted: 04/29/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE To investigate biases in the measurement of apparent alveolar septal wall thickness (SWT) with hyperpolarized xenon-129 (HXe) as a function of acquisition parameters. METHODS The HXe MRI scans with simultaneous gas-phase and dissolved-phase excitation were performed using 1-dimensional projection scans in mechanically ventilated rabbits. The dissolved-phase magnetization was periodically saturated, and the dissolved-phase xenon uptake dynamics were measured at end inspiration and end expiration with temporal resolutions up to 10 ms using a Look-Locker-type acquisition. The apparent alveolar septal wall thickness was extracted by fitting the signal to a theoretical model, and the findings were compared with those from the more commonly use chemical shift saturation recovery MRI spectroscopy technique with several different delay time arrangements. RESULTS It was found that repeated application of RF saturation pulses in chemical shift saturation recovery acquisitions caused exchange-dependent gas-phase saturation that heavily biased the derived SWT value. When this bias was reduced by our proposed method, the SWT dependence on lung inflation disappeared due to an inherent insensitivity of HXe dissolved-phase MRI to thin alveolar structures with very short T 2 ∗ . Furthermore, perfusion-based macroscopic gas transport processes were demonstrated to cause increasing apparent SWTs with TE (2.5 μm/ms at end expiration) and a lung periphery-to-center SWT gradient. CONCLUSION The apparent SWT measured with HXe MRI was found to be heavily dependent on the acquisition parameters. A method is proposed that can minimize this measurement bias, add limited spatial resolution, and reduce measurement time to a degree that free-breathing studies are feasible.
Collapse
Affiliation(s)
- Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Faraz Amzajerdian
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Luis Loza
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Tahmina Achekzai
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ian F Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| |
Collapse
|
10
|
Virgincar RS, Nouls JC, Wang Z, Degan S, Qi Y, Xiong X, Rajagopal S, Driehuys B. Quantitative 129Xe MRI detects early impairment of gas-exchange in a rat model of pulmonary hypertension. Sci Rep 2020; 10:7385. [PMID: 32355256 PMCID: PMC7193602 DOI: 10.1038/s41598-020-64361-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2020] [Indexed: 12/19/2022] Open
Abstract
Hyperpolarized 129Xe magnetic resonance imaging (MRI) is capable of regional mapping of pulmonary gas-exchange and has found application in a wide range of pulmonary disorders in humans and animal model analogs. This study is the first application of 129Xe MRI to the monocrotaline rat model of pulmonary hypertension. Such models of preclinical pulmonary hypertension, a disease of the pulmonary vasculature that results in right heart failure and death, are usually assessed with invasive procedures such as right heart catheterization and histopathology. The work here adapted from protocols from clinical 129Xe MRI to enable preclinical imaging of rat models of pulmonary hypertension on a Bruker 7 T scanner. 129Xe spectroscopy and gas-exchange imaging showed reduced 129Xe uptake by red blood cells early in the progression of the disease, and at a later time point was accompanied by increased uptake by barrier tissues, edema, and ventilation defects-all of which are salient characteristics of the monocrotaline model. Imaging results were validated by H&E histology, which showed evidence of remodeling of arterioles. This proof-of-concept study has demonstrated that hyperpolarized 129Xe MRI has strong potential to be used to non-invasively monitor the progression of pulmonary hypertension in preclinical models and potentially to also assess response to therapy.
Collapse
Affiliation(s)
- Rohan S Virgincar
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - John C Nouls
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Ziyi Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Simone Degan
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Yi Qi
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Xinyu Xiong
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | | | - Bastiaan Driehuys
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Department of Radiology, Duke University Medical Center, Durham, NC, USA.
| |
Collapse
|
11
|
Guo M, Qi L, Zhang Y, Shang D, Yu J, Yue J. 18F-Fluorodeoxyglucose positron emission tomography may not visualize radiation pneumonitis. EJNMMI Res 2019; 9:112. [PMID: 31858307 PMCID: PMC6923299 DOI: 10.1186/s13550-019-0571-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/04/2019] [Indexed: 12/29/2022] Open
Abstract
Background Radiation pneumonitis is a common and potentially fatal complication of radiotherapy (RT). Some patients with radiation pneumonitis show increases in uptake of fluorodeoxyglucose (FDG) on positron emission tomography (PET), but others do not. The exact relationship between radiation pneumonitis and 18F-FDG PET findings remains controversial. Methods We used an animal model of radiation pneumonitis involving both radiation and simulated bacterial infection in Wistar rats. Treatment groups (10 rats/group) were as follows: control, RT-only, lipopolysaccharide (LPS)-only, and RT+LPS. All rats had micro-PET scans at 7 weeks after RT (or sham). Histologic, immunohistochemical, and biochemical analyses were performed to evaluate potential mechanisms. Results Irradiated rats had developed radiation pneumonitis at 7 weeks after RT based on pathology and CT scans. Maximum and mean standardized uptake values (SUVmax and SUVmean) at that time were significantly increased in the LPS group (P < 0.001 for both) and the RT+LPS group (P < 0.001 for both) relative to control, but were not different in the RT-only group (P = 0.156 SUVmax and P = 0.304 SUVmean). The combination of RT and LPS increased the expression of the aerobic glycolysis enzyme PKM2 (P < 0.001) and the glucose transporter GLUT1 (P = 0.004) in lung tissues. LPS alone increased the expression of PKM2 (P = 0.018), but RT alone did not affect PKM2 (P = 0.270) or GLUT1 (P = 0.989). Conclusions Aseptic radiation pneumonitis could not be accurately assessed by 18F-FDG PET, but was visualized after simulated bacterial infection via LPS. The underlying mechanism of the model of bacterial infection causing increased FDG uptake may be the Warburg effect.
Collapse
Affiliation(s)
- Meiying Guo
- School of Medicine, Shandong University, Jinan, 250012, China.,Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, No. 440, Ji Yan Road, Jinan, 250117, China
| | - Liang Qi
- Equipment and material Department, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250117, China
| | - Yun Zhang
- Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, No. 440, Ji Yan Road, Jinan, 250117, China
| | - Dongping Shang
- Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, No. 440, Ji Yan Road, Jinan, 250117, China
| | - Jinming Yu
- Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, No. 440, Ji Yan Road, Jinan, 250117, China
| | - Jinbo Yue
- Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, No. 440, Ji Yan Road, Jinan, 250117, China.
| |
Collapse
|
12
|
Friedlander Y, Zanette B, Lindenmaier A, Sadanand S, Li D, Stirrat E, Couch M, Kassner A, Jankov RP, Santyr G. Chemical shift of
129
Xe dissolved in red blood cells: Application to a rat model of bronchopulmonary dysplasia. Magn Reson Med 2019; 84:52-60. [DOI: 10.1002/mrm.28121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/13/2019] [Accepted: 11/19/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Yonni Friedlander
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
- Department of Medical Biophysics University of Toronto Toronto Ontario Canada
| | - Brandon Zanette
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
| | - Andras Lindenmaier
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
- Department of Medical Biophysics University of Toronto Toronto Ontario Canada
| | - Siddharth Sadanand
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
| | - Daniel Li
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
| | - Elaine Stirrat
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
| | - Marcus Couch
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
- Department of Medical Biophysics University of Toronto Toronto Ontario Canada
| | - Andrea Kassner
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
- Department of Medical Imaging University of Toronto Toronto Ontario Canada
| | - Robert P. Jankov
- Molecular Biomedicine Program Children’s Hospital of Eastern Ontario Research Institute Ottawa Ontario Canada
- Department of Cellular and Molecular Medicine University of Ottawa Ottawa Ontario Canada
| | - Giles Santyr
- Translational Medicine Program Hospital for Sick Children Toronto Ontario Canada
- Department of Medical Biophysics University of Toronto Toronto Ontario Canada
| |
Collapse
|
13
|
Riberdy V, Litvack M, Stirrat E, Couch M, Post M, Santyr GE. Hyperpolarized 129 Xe imaging of embryonic stem cell-derived alveolar-like macrophages in rat lungs: proof-of-concept study using superparamagnetic iron oxide nanoparticles. Magn Reson Med 2019; 83:1356-1367. [PMID: 31556154 DOI: 10.1002/mrm.27999] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 07/18/2019] [Accepted: 08/25/2019] [Indexed: 12/29/2022]
Abstract
PURPOSE To measure regional changes in hyperpolarized 129 Xe MRI signal and apparent transverse relaxation ( T 2 ∗ ) because of instillation of SPION-labeled alveolar-like macrophages (ALMs) in the lungs of rats and compare to histology. METHODS MRI was performed in 6 healthy mechanically ventilated rats before instillation, as well as 5 min and 1 h after instillation of 4 million SPION-labeled ALMs into either the left or right lung. T 2 ∗ maps were calculated from 2D multi-echo data at each time point and changes in T 2 ∗ were measured and compared to control rats receiving 4 million unlabeled ALMs. Histology of the ex vivo lungs was used to compare the regional MRI findings with the locations of the SPION-labeled ALMs. RESULTS Regions of signal loss were observed immediately after instillation of unlabeled and SPION-labeled ALMs and persisted at least 1 h in the case of the SPION-labeled ALMs. This was reflected in the measurements of T 2 ∗ . One hour after the instillation of SPION-labeled ALMs, the T 2 ∗ decreased to 54.0 ± 7.0% of the baseline, compared to a full recovery to baseline after the instillation of unlabeled ALMs. Histology confirmed the co-localization of SPION-labeled ALMs with regions of signal loss and T 2 ∗ decreases for each rat. CONCLUSION Hyperpolarized 129 Xe MRI can detect the presence of SPION-labeled ALMs in the airways 1 h after instillation. This approach is promising for targeting and tracking of stem cells for the treatment of lung disease.
Collapse
Affiliation(s)
- Vlora Riberdy
- Translational Medicine Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Michael Litvack
- Translational Medicine Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, Canada
| | - Elaine Stirrat
- Translational Medicine Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, Canada
| | - Marcus Couch
- Translational Medicine Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Martin Post
- Translational Medicine Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
| | - Giles E Santyr
- Translational Medicine Program, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Canada
| |
Collapse
|
14
|
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]
|
15
|
Zanette B, Santyr G. Accelerated interleaved spiral-IDEAL imaging of hyperpolarized 129 Xe for parametric gas exchange mapping in humans. Magn Reson Med 2019; 82:1113-1119. [PMID: 30989730 DOI: 10.1002/mrm.27765] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 01/22/2019] [Accepted: 03/18/2019] [Indexed: 12/24/2022]
Abstract
PURPOSE To demonstrate the feasibility of mapping gas exchange with single breath-hold hyperpolarized (HP) 129 Xe in humans, acquiring parametric maps of lung physiology. The potential benefit of acceleration using parallel imaging for this application is also explored. METHODS Six healthy volunteers were scanned with a modified spiral-IDEAL sequence to acquire gas exchange-weighted images using a single dose of 129 Xe. These images were fit with the model of xenon exchange (MOXE) on a voxel-wise basis calculating parametric maps of lung physiology, specifically: air-capillary barrier thickness (δ), alveolar septal thickness (d), capillary transit time (tx ), pulmonary hematocrit (HCT), and alveolar surface area-to-volume ratio (SVR). An accelerated version of the sequence was also tested in subset of 4 volunteers and compared to the fully sampled (FS) results. RESULTS Mean image-wide values calculated from MOXE parametric maps derived from FS dissolved 129 Xe spiral-IDEAL images were: δ = 0.89 ± 0.17 μm, d = 7.5 ± 0.5 μm, tx = 1.1 ± 0.2s, HCT = 28.8 ± 2.3%, and SVR = 140 ± 16 cm-1 , in good agreement with previously published values based on whole-lung spectroscopy of healthy human subjects. Parallel imaging sufficiently reduces artifacting in accelerated images, but increases disagreement with MOXE parameters derived from FS data with mean voxel-wise unsigned relative differences of: δ = 39 ± 9%, d = 22 ± 3%, tx = 117 ± 43%, HCT = 11 ± 2%, and SVR = 31 ± 12%. CONCLUSION Dissolved HP 129 Xe spiral-IDEAL imaging for gas exchange mapping is feasible in humans using a single breath-hold. Accelerated gas exchange mapping is also shown to be feasible but requires further improvements to increase quantitative accuracy.
Collapse
Affiliation(s)
- Brandon Zanette
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Giles Santyr
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
| |
Collapse
|
16
|
Using Hyperpolarized Xenon-129 MRI to Quantify Early-Stage Lung Disease in Smokers. Acad Radiol 2019; 26:355-366. [PMID: 30522808 DOI: 10.1016/j.acra.2018.11.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/04/2018] [Accepted: 11/16/2018] [Indexed: 12/25/2022]
Abstract
RATIONALE AND OBJECTIVES Hyperpolarized xenon-129 magnetic resonance (MR) provides sensitive tools that may detect early stages of lung disease in smokers before it has progressed to chronic obstructive pulmonary disease (COPD) apparent to conventional spirometric measures. We hypothesized that the functional alveolar wall thickness as assessed by hyperpolarized xenon-129 MR spectroscopy would be elevated in clinically healthy smokers before xenon MR diffusion measurements would indicate emphysematous tissue destruction. MATERIALS AND METHODS Using hyperpolarized xenon-129 MR we measured the functional septal wall thickness and apparent diffusion coefficient of the gas phase in 16 subjects with smoking-related COPD, 9 clinically healthy current or former smokers, and 10 healthy never smokers. All subjects were age-matched and characterized by conventional pulmonary function tests. A total of 11 data sets from younger healthy never smokers were added to determine the age dependence of the septal wall thickness measurements. RESULTS In healthy never smokers the septal wall thickness increased by 0.04 μm per year of age. The healthy smoker cohort exhibited normal pulmonary function test measures that did not significantly differ from the never-smoker cohort. The age-corrected septal wall thickness correlated well with diffusion capacity for carbon monoxide (R2 = 0.56) and showed a highly significant difference between healthy subjects and COPD patients (8.8 μm vs 12.3 μm; p < 0.001), but was the only measure that actually discriminated healthy subjects from healthy smokers (8.8 μm vs 10.6 μm; p < 0.006). CONCLUSION Functional alveolar wall thickness assessed by hyperpolarized xenon-129 MR allows discrimination between healthy subjects and healthy smokers and could become a powerful new measure of early-stage lung disease.
Collapse
|
17
|
Ruppert K, Xin Y, Hamedani H, Amzajerdian F, Loza L, Achekzai T, Duncan IF, Profka H, Siddiqui S, Pourfathi M, Sertic F, Cereda MF, Kadlecek S, Rizi RR. Measurement of Regional 2D Gas Transport Efficiency in Rabbit Lung Using Hyperpolarized 129Xe MRI. Sci Rep 2019; 9:2413. [PMID: 30787357 PMCID: PMC6382756 DOI: 10.1038/s41598-019-38942-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/11/2018] [Indexed: 01/25/2023] Open
Abstract
While hyperpolarized xenon-129 (HXe) MRI offers a wide array of tools for assessing functional aspects of the lung, existing techniques provide only limited quantitative information about the impact of an observed pathology on overall lung function. By selectively destroying the alveolar HXe gas phase magnetization in a volume of interest and monitoring the subsequent decrease in the signal from xenon dissolved in the blood inside the left ventricle of the heart, it is possible to directly measure the contribution of that saturated lung volume to the gas transport capacity of the entire lung. In mechanically ventilated rabbits, we found that both xenon gas transport and transport efficiency exhibited a gravitation-induced anterior-to-posterior gradient that disappeared or reversed direction, respectively, when the animal was turned from supine to prone position. Further, posterior ventilation defects secondary to acute lung injury could be re-inflated by applying positive end expiratory pressure, although at the expense of decreased gas transport efficiency in the anterior volumes. These findings suggest that our technique might prove highly valuable for evaluating lung transplants and lung resections, and could improve our understanding of optimal mechanical ventilator settings in acute lung injury.
Collapse
Affiliation(s)
- Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Faraz Amzajerdian
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Luis Loza
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Tahmina Achekzai
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ian F Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Sarmad Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Federico Sertic
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Maurizio F Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| |
Collapse
|
18
|
Doganay O, Chen M, Matin T, Rigolli M, Phillips JA, McIntyre A, Gleeson FV. Magnetic resonance imaging of the time course of hyperpolarized 129Xe gas exchange in the human lungs and heart. Eur Radiol 2018; 29:2283-2292. [PMID: 30519929 PMCID: PMC6443604 DOI: 10.1007/s00330-018-5853-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/27/2018] [Accepted: 10/23/2018] [Indexed: 12/23/2022]
Abstract
Purpose To perform magnetic resonance imaging (MRI), human lung imaging, and quantification of the gas-transfer dynamics of hyperpolarized xenon-129 (HPX) from the alveoli into the blood plasma. Materials and methods HPX MRI with iterative decomposition of water and fat with echo asymmetry and least-square estimation (IDEAL) approach were used with multi-interleaved spiral k-space sampling to obtain HPX gas and dissolved phase images. IDEAL time-series images were then obtained from ten subjects including six normal subjects and four patients with pulmonary emphysema to test the feasibility of the proposed technique for capturing xenon-129 gas-transfer dynamics (XGTD). The dynamics of xenon gas diffusion over the entire lung was also investigated by measuring the signal intensity variations between three regions of interest, including the left and right lungs and the heart using Welch’s t test. Results The technique enabled the acquisition of HPX gas and dissolved phase compartment images in a single breath-hold interval of 8 s. The y-intersect of the XGTD curves were also found to be statistically lower in the patients with lung emphysema than in the healthy group (p < 0.05). Conclusion This time-series IDEAL technique enables the visualization and quantification of inhaled xenon from the alveoli to the left ventricle with a clinical gradient strength magnet during a single breath-hold, in healthy and diseased lungs. Key Points • The proposed hyperpolarized xenon-129 gas and dissolved magnetic resonance imaging technique can provide regional and temporal measurements of xenon-129 gas-transfer dynamics. • Quantitative measurement of xenon-129 gas-transfer dynamics from the alveolar to the heart was demonstrated in normal subjects and pulmonary emphysema. • Comparison of gas-transfer dynamics in normal subjects and pulmonary emphysema showed that the proposed technique appears sensitive to changes affecting the alveoli, pulmonary interstitium, and capillaries. Electronic supplementary material The online version of this article (10.1007/s00330-018-5853-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Ozkan Doganay
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, UK. .,Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Rd, Oxford, OX3 7LE, UK.
| | - Mitchell Chen
- Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Rd, Oxford, OX3 7LE, UK
| | - Tahreema Matin
- Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Rd, Oxford, OX3 7LE, UK
| | - Marzia Rigolli
- University of Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Julie-Ann Phillips
- Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Rd, Oxford, OX3 7LE, UK
| | - Anthony McIntyre
- Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Rd, Oxford, OX3 7LE, UK
| | - Fergus V Gleeson
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, UK.,Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Old Rd, Oxford, OX3 7LE, UK
| |
Collapse
|
19
|
Kern AL, Gutberlet M, Voskrebenzev A, Klimeš F, Rotärmel A, Wacker F, Hohlfeld JM, Vogel‐Claussen J. Mapping of regional lung microstructural parameters using hyperpolarized
129
Xe dissolved‐phase MRI in healthy volunteers and patients with chronic obstructive pulmonary disease. Magn Reson Med 2018; 81:2360-2373. [DOI: 10.1002/mrm.27559] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/14/2018] [Accepted: 09/14/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Agilo L. Kern
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| | - Marcel Gutberlet
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| | - Andreas Voskrebenzev
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| | - Filip Klimeš
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| | - Alexander Rotärmel
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| | - Frank Wacker
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| | - Jens M. Hohlfeld
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
- Clinical Airway Research Fraunhofer Institute for Toxicology and Experimental Medicine Hannover Germany
- Department of Respiratory Medicine Hannover Medical School Hannover Germany
| | - Jens Vogel‐Claussen
- Diagnostic and Interventional Radiology Hannover Medical School Hannover Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH) Member of the German Center for Lung Research (DZL) Hannover Germany
| |
Collapse
|
20
|
Ruppert K, Amzajerdian F, Hamedani H, Xin Y, Loza L, Achekzai T, Duncan IF, Profka H, Siddiqui S, Pourfathi M, Sertic F, Cereda MF, Kadlecek S, Rizi RR. Assessment of flip angle-TR equivalence for standardized dissolved-phase imaging of the lung with hyperpolarized 129Xe MRI. Magn Reson Med 2018; 81:1784-1794. [PMID: 30346083 DOI: 10.1002/mrm.27538] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 08/20/2018] [Accepted: 08/27/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE To investigate the feasibility of describing the impact of any flip angle-TR combination on the resulting distribution of the hyperpolarized xenon-129 (HXe) dissolved-phase magnetization in the chest using a single virtual parameter, TR90°,equiv . METHODS HXe MRI scans with simultaneous gas- (GP) and dissolved-phase (DP) excitation were performed using 2D projection scans in mechanically ventilated rabbits. Measurements with DP flip angles ranging from 6-90° and TRs ranging from 8.3-500 ms were conducted. DP maps based on acquisitions of similar radio frequency pulse-induced relaxation rates were compared. RESULTS The observed distribution of the DP magnetization was strongly affected by acquisition flip angle and TR. However, for flip angles up to 60°, measurements with the same radio frequency pulse-induced relaxation rates, resulted in very similar DP images despite the presence of significant macroscopic gas transport processes. For flip angles approaching 90°, the downstream signal component decreased noticeably relative to acquisitions with lower flip angles. Nevertheless, the total DP signal continued to follow an empirically verified conversion equation over the entire investigated parameter range, which yields the equivalent TR of a hypothetical 90° measurement for any experimental flip angle-TR combination. CONCLUSION We have introduced a method for converting the flip angle and TR of a given HXe DP measurement to a standardized metric based on the virtual quantity, TR90°,equiv , using their equivalent RF relaxation rates. This conversion permits the comparison of measurements obtained with different pulse sequence types or by different research groups using various acquisition parameters.
Collapse
Affiliation(s)
- Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Faraz Amzajerdian
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Luis Loza
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Tahmina Achekzai
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ian F Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sarmad Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Federico Sertic
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Maurizio F Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|
21
|
Ruppert K, Hamedani H, Amzajerdian F, Xin Y, Duncan IF, Profka H, Siddiqui S, Pourfathi M, Kadlecek S, Rizi RR. Assessment of Pulmonary Gas Transport in Rabbits Using Hyperpolarized Xenon-129 Magnetic Resonance Imaging. Sci Rep 2018; 8:7310. [PMID: 29743565 PMCID: PMC5943289 DOI: 10.1038/s41598-018-25713-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 04/09/2018] [Indexed: 02/07/2023] Open
Abstract
Many forms of lung disease manifest themselves as pathological changes in the transport of gas to the circulatory system, yet the difficulty of imaging this process remains a central obstacle to the comprehensive diagnosis of lung disorders. Using hyperpolarized xenon-129 as a surrogate marker for oxygen, we derived the temporal dynamics of gas transport from the ratio of two lung images obtained with different timing parameters. Additionally, by monitoring changes in the total hyperpolarized xenon signal intensity in the left side of the heart induced by depletion of xenon signal in the alveolar airspaces of interest, we quantified the contributions of selected lung volumes to the total pulmonary gas transport. In a rabbit model, we found that it takes at least 200 ms for xenon gas to enter the lung tissue and travel the distance from the airspaces to the heart. Additionally, our method shows that both lungs contribute fairly equally to the gas transport in healthy rabbits, but that this ratio changes in a rabbit model of acid aspiration. These results suggest that hyperpolarized xenon-129 MRI may improve our ability to measure pulmonary gas transport and detect associated pathological changes.
Collapse
Affiliation(s)
- Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Faraz Amzajerdian
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ian F Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Sarmad Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| |
Collapse
|
22
|
Ruppert K, Amzajerdian F, Hamedani H, Xin Y, Loza L, Achekzai T, Duncan IF, Profka H, Siddiqui S, Pourfathi M, Cereda MF, Kadlecek S, Rizi RR. Rapid assessment of pulmonary gas transport with hyperpolarized 129Xe MRI using a 3D radial double golden-means acquisition with variable flip angles. Magn Reson Med 2018; 80:2439-2448. [PMID: 29682792 DOI: 10.1002/mrm.27217] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 03/20/2018] [Accepted: 03/24/2018] [Indexed: 12/15/2022]
Abstract
PURPOSE To demonstrate the feasibility of using a 3D radial double golden-means acquisition with variable flip angles to monitor pulmonary gas transport in a single breath hold with hyperpolarized xenon-129 MRI. METHODS Hyperpolarized xenon-129 MRI scans with interleaved gas-phase and dissolved-phase excitations were performed using a 3D radial double golden-means acquisition in mechanically ventilated rabbits. The flip angle was either held fixed at 15 ° or 5 °, or it was varied linearly in ascending or descending order between 5 ° and 15 ° over a sampling interval of 1000 spokes. Dissolved-phase and gas-phase images were reconstructed at high resolution (32 × 32 × 32 matrix size) using all 1000 spokes, or at low resolution (22 × 22 × 22 matrix size) using 400 spokes at a time in a sliding-window fashion. Based on these sliding-window images, relative change maps were obtained using the highest mean flip angle as the reference, and aggregated pixel-based changes were tracked. RESULTS Although the signal intensities in the dissolve-phase maps were mostly constant in the fixed flip-angle acquisitions, they varied significantly as a function of average flip angle in the variable flip-angle acquisitions. The latter trend reflects the underlying changes in observed dissolve-phase magnetization distribution due to pulmonary gas uptake and transport. CONCLUSION 3D radial double golden-means acquisitions with variable flip angles provide a robust means for rapidly assessing lung function during a single breath hold, thereby constituting a particularly valuable tool for imaging uncooperative or pediatric patient populations.
Collapse
Affiliation(s)
- Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Faraz Amzajerdian
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Luis Loza
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Tahmina Achekzai
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ian F Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sarmad Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Maurizio F Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|