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Babaeipour R, Ouriadov A, Fox MS. Deep Learning Approaches for Quantifying Ventilation Defects in Hyperpolarized Gas Magnetic Resonance Imaging of the Lung: A Review. Bioengineering (Basel) 2023; 10:1349. [PMID: 38135940 PMCID: PMC10740978 DOI: 10.3390/bioengineering10121349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/06/2023] [Accepted: 11/21/2023] [Indexed: 12/24/2023] Open
Abstract
This paper provides an in-depth overview of Deep Neural Networks and their application in the segmentation and analysis of lung Magnetic Resonance Imaging (MRI) scans, specifically focusing on hyperpolarized gas MRI and the quantification of lung ventilation defects. An in-depth understanding of Deep Neural Networks is presented, laying the groundwork for the exploration of their use in hyperpolarized gas MRI and the quantification of lung ventilation defects. Five distinct studies are examined, each leveraging unique deep learning architectures and data augmentation techniques to optimize model performance. These studies encompass a range of approaches, including the use of 3D Convolutional Neural Networks, cascaded U-Net models, Generative Adversarial Networks, and nnU-net for hyperpolarized gas MRI segmentation. The findings highlight the potential of deep learning methods in the segmentation and analysis of lung MRI scans, emphasizing the need for consensus on lung ventilation segmentation methods.
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Affiliation(s)
- Ramtin Babaeipour
- School of Biomedical Engineering, Faculty of Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada;
| | - Alexei Ouriadov
- School of Biomedical Engineering, Faculty of Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada;
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada;
- Lawson Health Research Institute, London, ON N6C 2R5, Canada
| | - Matthew S. Fox
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada;
- Lawson Health Research Institute, London, ON N6C 2R5, Canada
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2
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Perron S, McCormack DG, Parraga G, Ouriadov A. Undersampled Diffusion-Weighted 129Xe MRI Morphometry of Airspace Enlargement: Feasibility in Chronic Obstructive Pulmonary Disease. Diagnostics (Basel) 2023; 13:diagnostics13081477. [PMID: 37189579 DOI: 10.3390/diagnostics13081477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/10/2023] [Accepted: 04/18/2023] [Indexed: 05/17/2023] Open
Abstract
Multi-b diffusion-weighted hyperpolarized gas MRI measures pulmonary airspace enlargement using apparent diffusion coefficients (ADC) and mean linear intercepts (Lm). Rapid single-breath acquisitions may facilitate clinical translation, and, hence, we aimed to develop single-breath three-dimensional multi-b diffusion-weighted 129Xe MRI using k-space undersampling. We evaluated multi-b (0, 12, 20, 30 s/cm2) diffusion-weighted 129Xe ADC/morphometry estimates using a fully sampled and retrospectively undersampled k-space with two acceleration-factors (AF = 2 and 3) in never-smokers and ex-smokers with chronic obstructive pulmonary disease (COPD) or alpha-one anti-trypsin deficiency (AATD). For the three sampling cases, mean ADC/Lm values were not significantly different (all p > 0.5); ADC/Lm values were significantly different for the COPD subgroup (0.08 cm2s-1/580 µm, AF = 3; all p < 0.001) as compared to never-smokers (0.05 cm2s-1/300 µm, AF = 3). For never-smokers, mean differences of 7%/7% and 10%/7% were observed between fully sampled and retrospectively undersampled (AF = 2/AF = 3) ADC and Lm values, respectively. For the COPD subgroup, mean differences of 3%/4% and 11%/10% were observed between fully sampled and retrospectively undersampled (AF = 2/AF = 3) ADC and Lm, respectively. There was no relationship between acceleration factor with ADC or Lm (p = 0.9); voxel-wise ADC/Lm measured using AF = 2 and AF = 3 were significantly and strongly related to fully-sampled values (all p < 0.0001). Multi-b diffusion-weighted 129Xe MRI is feasible using two different acceleration methods to measure pulmonary airspace enlargement using Lm and ADC in COPD participants and never-smokers.
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Affiliation(s)
- Samuel Perron
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - David G McCormack
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Grace Parraga
- Robarts Research Institute, London, ON N6A 5B7, Canada
- Department of Medical Biophysics, The University of Western Ontario, London, ON N6A 3K7, Canada
- Graduate Program in Biomedical Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Alexei Ouriadov
- Robarts Research Institute, London, ON N6A 5B7, Canada
- Department of Medical Biophysics, The University of Western Ontario, London, ON N6A 3K7, Canada
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3
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Matheson AM, McIntosh MJ, Kooner HK, Abdelrazek M, Albert MS, Dhaliwal I, Nicholson JM, Ouriadov A, Svenningsen S, Parraga G. Longitudinal follow-up of postacute COVID-19 syndrome: DL CO, quality-of-life and MRI pulmonary gas-exchange abnormalities. Thorax 2023; 78:418-421. [PMID: 36596692 PMCID: PMC10086459 DOI: 10.1136/thorax-2022-219378] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 12/15/2022] [Indexed: 01/05/2023]
Abstract
129Xe MRI red blood cell to alveolar tissue plasma ratio (RBC:TP) abnormalities have been observed in ever-hospitalised and never-hospitalised people with postacute COVID-19 syndrome (PACS). But, it is not known if such abnormalities resolve when symptoms and quality-of-life scores improve. We evaluated 21 participants with PACS, 7±4 months (baseline) and 14±4 months (follow-up) postinfection. Significantly improved diffusing capacity of the lung for carbon monoxide (DLCO, Δ=14%pred ;95%CI 7 to 21, p<0.001), postexertional dyspnoea (Δ=-0.7; 95%CI=-0.2 to -1.2, p=0.019), St George's Respiratory Questionnaire-score (SGRQ Δ=-6; 95% CI=-1 to -11, p=0.044) but not RBC:TP (Δ=0.03; 95% CI=0.01 to 0.05, p=0.051) were observed at 14 months. DLCO correlated with RBC:TP (r=0.60, 95% CI=0.22 to 0.82, p=0.004) at 7 months. While DLCO and SGRQ measurements improved, these values did not normalise 14 months post-infection. ClinicalTrials.gov NCT04584671.
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Affiliation(s)
- Alexander M Matheson
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Marrissa J McIntosh
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Harkiran K Kooner
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Mohamed Abdelrazek
- Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada
| | - Mitchell S Albert
- Department of Chemistry, Lakehead University, Thunder Bay, Ontario, Canada
| | - Inderdeep Dhaliwal
- Division of Respirology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - J Michael Nicholson
- Division of Respirology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Alexei Ouriadov
- Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada
| | - Sarah Svenningsen
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Grace Parraga
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada .,Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada.,Division of Respirology, Department of Medicine, University of Western Ontario, London, Ontario, Canada.,Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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4
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Perron S, Ouriadov A. Hyperpolarized 129Xe MRI at low field: Current status and future directions. J Magn Reson 2023; 348:107387. [PMID: 36731353 DOI: 10.1016/j.jmr.2023.107387] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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Kooner HK, McIntosh MJ, Matheson AM, Abdelrazek M, Albert MS, Dhaliwal I, Kirby M, Ouriadov A, Santyr GE, Venegas C, Radadia N, Svenningsen S, Nicholson JM, Parraga G. Post-Acute COVID-19 Syndrome: 129Xe MRI Ventilation Defects and Respiratory Outcomes One Year Later. Radiology 2023; 307:e222557. [PMID: 36749209 PMCID: PMC9926501 DOI: 10.1148/radiol.222557] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Background In people with post-acute COVID-19 syndrome (PACS) and normal pulmonary function, 129Xe MRI ventilation defects, abnormal quality-of-life scores, and exercise limitation were reported 3-months after infection; the longitudinal trajectory remains unclear. Purpose To measure and compare pulmonary function, exercise capacity, quality-of-life, and 129Xe MRI ventilation defect percent (VDP) in people with PACS evaluated 3- and 15-months post-infection. Materials and Methods In this prospective study, participants with PACS aged 18-80 years were enrolled between July 2020 and August 2021 from two quaternary care centers. They were evaluated 3-months and 15-months post-infection for: 129Xe MRI VDP, diffusing capacity of the lung for carbon monoxide (DLCO), spirometry, oscillometry, six-minute walk distance (6MWD), and St. George's Respiratory Questionnaire (SGRQ). Differences between time-points were evaluated using paired t-tests. Multivariable models were generated to explain exercise capacity and quality-of-life improvements. Odds ratios (OR) were used to evaluate potential treatment influences. Results Fifty-three participants (mean age, 55 years ±18[SD]; 26 male; 27 female) attended both 3- and 15-month visits and were included in analysis. 129Xe MRI VDP (5.4%, 4.2%; P=.003), forced expiratory volume in 1-second (85%pred, 90%pred; P=.001), DLCO (89%pred, 99%pred; P=.002) and SGRQ (35, 25; P<.001) improved between the 3- and 15-month visit. VDP measured at 3- months post-COVID predicted the change in 6MWD (β=-.643, P=.001) while treatment with respiratory medication at 3-months predicted improved 15-month quality-of-life score (OR=4.0; 95%CI:1.2,13.8, P=.03). Conclusion Pulmonary function, gas-exchange, exercise capacity, quality-of-life, and 129Xe MRI ventilation defect percent (VDP) improved in participants with post-acute COVID-19 syndrome evaluated at 15-months as compared to 3-months post-infection. VDP measured at 3-months post-infection correlated with improved exercise capacity, whilst treatment with respiratory medication was associated with improved quality-of-life score at 15-months post-infection. Clinical Trial Registration: www.clinicaltrials.gov NCT05014516 See also the editorial by Vogel-Claussen in this issue.
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Affiliation(s)
| | | | | | | | | | - Inderdeep Dhaliwal
- Division of Respirology, Department of Medicine, Western University,
London, Canada
| | - Miranda Kirby
- Department of Physics, Toronto Metropolitan University, Toronto,
Canada
| | - Alexei Ouriadov
- Department of Physics and Astronomy, Western University, London,
Canada
| | | | - Carmen Venegas
- Division of Respirology, Department of Medicine, McMaster University
and Firestone Institute for Respiratory Health, St Joseph's Health Care,
Hamilton, Canada
| | - Nisarg Radadia
- Division of Respirology, Department of Medicine, McMaster University
and Firestone Institute for Respiratory Health, St Joseph's Health Care,
Hamilton, Canada
| | - Sarah Svenningsen
- Division of Respirology, Department of Medicine, McMaster University
and Firestone Institute for Respiratory Health, St Joseph's Health Care,
Hamilton, Canada
| | - J Michael Nicholson
- Division of Respirology, Department of Medicine, Western University,
London, Canada
| | - Grace Parraga
- Robarts Research Institute,Department of Medical Biophysics,Department of Medical Imaging, Western University, London,
Canada,Division of Respirology, Department of Medicine, Western University,
London, Canada
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Sembhi R, Ranota T, Fox M, Couch M, Li T, Ball I, Ouriadov A. Feasibility of Dynamic Inhaled Gas MRI-Based Measurements Using Acceleration Combined with the Stretched Exponential Model. Diagnostics (Basel) 2023; 13:diagnostics13030506. [PMID: 36766611 PMCID: PMC9914115 DOI: 10.3390/diagnostics13030506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/22/2023] [Accepted: 01/28/2023] [Indexed: 02/01/2023] Open
Abstract
Dynamic inhaled gas (3He/129Xe/19F) MRI permits the acquisition of regional fractional-ventilation which is useful for detecting gas-trapping in lung-diseases such as lung fibrosis and COPD. Deninger's approach used for analyzing the wash-out data can be substituted with the stretched-exponential-model (SEM) because signal-intensity is attenuated as a function of wash-out-breath in 19F lung imaging. Thirteen normal-rats were studied using 3He/129Xe and 19F MRI and the ventilation measurements were performed using two 3T clinical-scanners. Two Cartesian-sampling-schemes (Fast-Gradient-Recalled-Echo/X-Centric) were used to test the proposed method. The fully sampled dynamic wash-out images were retrospectively under-sampled (acceleration-factors (AF) of 10/14) using a varying-sampling-pattern in the wash-out direction. Mean fractional-ventilation maps using Deninger's and SEM-based approaches were generated. The mean fractional-ventilation-values generated for the fully sampled k-space case using the Deninger method were not significantly different from other fractional-ventilation-values generated for the non-accelerated/accelerated data using both Deninger and SEM methods (p > 0.05 for all cases/gases). We demonstrated the feasibility of the SEM-based approach using retrospective under-sampling, mimicking AF = 10/14 in a small-animal-cohort from the previously reported dynamic-lung studies. A pixel-by-pixel comparison of the Deninger-derived and SEM-derived fractional-ventilation-estimates obtained for AF = 10/14 (≤16% difference) has confirmed that even at AF = 14, the accuracy of the estimates is high enough to consider this method for prospective measurements.
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Affiliation(s)
- Ramanpreet Sembhi
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Tuneesh Ranota
- Faculty of Engineering, School of Biomedical Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Matthew Fox
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
- Lawson Health Research Institute, London, ON N6C 2R5, Canada
| | - Marcus Couch
- Siemens Healthcare Limited, Montreal, QC H4R 2N9, Canada
| | - Tao Li
- Department of Chemistry, Lakehead University, Thunder Bay, ON P7B 5E1, Canada
| | - Iain Ball
- Philips Australia and New Zealand, Sydney 2113, Australia
| | - Alexei Ouriadov
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
- Faculty of Engineering, School of Biomedical Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
- Lawson Health Research Institute, London, ON N6C 2R5, Canada
- Correspondence:
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Matheson AM, McIntosh MJ, Kooner HK, Lee J, Desaigoudar V, Bier E, Driehuys B, Svenningsen S, Santyr GE, Kirby M, Albert MS, Shepelytskyi Y, Grynko V, Ouriadov A, Abdelrazek M, Dhaliwal I, Nicholson JM, Parraga G. Persistent 129Xe MRI Pulmonary and CT Vascular Abnormalities in Symptomatic Individuals with Post-Acute COVID-19 Syndrome. Radiology 2022; 305:466-476. [PMID: 35762891 PMCID: PMC9272782 DOI: 10.1148/radiol.220492] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Background In patients with post-acute COVID-19-syndrome (PACS), abnormal gas-transfer and pulmonary vascular density have been reported, but such findings have not been related to each other, or to symptoms and exercise limitation. The pathophysiological drivers of PACS in ever- and never-hospitalized patients are not well-understood. Purpose To determine the relationship of persistent symptoms and exercise limitation with 129Xe MRI and CT pulmonary vascular measurements in individuals with PACS. Materials and Methods In this prospective study, patients with PACS aged 18-80 years with a positive PCR COVID test were recruited from a quaternary-care COVID-19 clinic between April and October 2021. Participants with PACS underwent spirometry, diffusing-capacity-of-the-lung- for-carbon-monoxide (DLco), 129Xe MRI, and chest CT. Healthy controls had no prior history of COVID-19 underwent spirometry, DLco, and 129Xe MRI. The 129Xe MRI red-blood-cell (RBC) to alveolar-barrier signal ratio, RBC area-under-the-curve (AUC), CT volume-of-pulmonary-vessels with cross-sectional-area <5mm2 (BV5), and total-blood-volume (TBV) were quantified. St. George's Respiratory Questionnaire (SGRQ), International Physical Activity Questionnaire (IPAQ) and modified Borg Dyspnea Scale (mBDS) measured quality-of-life, exercise limitation and dyspnea. Differences between groups were compared using Welch's T-tests or Welch's ANOVA. Relationships were evaluated using Pearson (r) and Spearman (ρ) correlations. Results Forty participants were evaluated including six controls (mean age, 35±15 years[standard deviation], 3 women) and 34 participants with PACS (mean age, 53±13 years[SD], 18 women), of which 22 were never-hospitalized. The 129Xe MRI RBC:barrier ratio was lower in ever- hospitalized participants (P=.04) compared to controls. BV5 correlated with RBC AUC (ρ=.44,P=.03). The 129Xe MRI RBC:barrier ratio was related to DLco (r=.57,P=.002) and FEV1 (ρ=.35,P=.03); RBC AUC was related to dyspnea (ρ=-.35,P=.04) and IPAQ score (ρ=.45,P=.02). Conclusion 129Xe MRI measurements were lower in ever- hospitalized participants with post- acute COVID-19-syndrome, 34±25 weeks post-infection compared to controls. 129Xe MRI measures were associated with CT pulmonary vascular density, DLco, exercise capacity, and dyspnea. ClinicalTrials.gov: NCT04584671 See also the editorial by Wild and Collier.
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Affiliation(s)
| | | | | | - Justin Lee
- Department of Physiology and Pharmacology, Western University, London Canada
| | | | - Elianna Bier
- Center for In Vivo Microscopy, Duke University Medical Center, Durham NC USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham NC USA
| | - Sarah Svenningsen
- Division of Respirology, Department of Medicine, McMaster University, Hamilton Canada
| | - Giles E Santyr
- Translational Medicine Program, Hospital for Sick Children, Toronto Canada.,Department of Medical Biophysics, University of Toronto, Toronto Canada
| | - Miranda Kirby
- Department of Physics, Ryerson University, Toronto Canada
| | - Mitchell S Albert
- Chemistry Department, Lakehead University.,Thunder Bay Regional Health Research Institute.,Northern Ontario School of Medicine, Thunder Bay Canada
| | - Yurii Shepelytskyi
- Chemistry Department, Lakehead University.,Thunder Bay Regional Health Research Institute
| | - Vira Grynko
- Chemistry Department, Lakehead University.,Thunder Bay Regional Health Research Institute
| | | | | | - Inderdeep Dhaliwal
- Division of Respirology, Department of Medicine, Western University, London Canada
| | - J Michael Nicholson
- Division of Respirology, Department of Medicine, Western University, London Canada
| | - Grace Parraga
- Robarts Research Institute.,Department of Medical Biophysics.,Department of Physiology and Pharmacology, Western University, London Canada.,Department of Medical Imaging.,Division of Respirology, Department of Medicine, Western University, London Canada
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8
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Kooner HK, McIntosh MJ, Matheson AM, Venegas C, Radadia N, Ho T, Haider EA, Konyer NB, Santyr GE, Albert MS, Ouriadov A, Abdelrazek M, Kirby M, Dhaliwal I, Nicholson JM, Nair P, Svenningsen S, Parraga G. 129Xe MRI ventilation defects in ever-hospitalised and never-hospitalised people with post-acute COVID-19 syndrome. BMJ Open Respir Res 2022; 9:9/1/e001235. [PMID: 35584850 PMCID: PMC9119175 DOI: 10.1136/bmjresp-2022-001235] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/05/2022] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Patients often report persistent symptoms beyond the acute infectious phase of COVID-19. Hyperpolarised 129Xe MRI provides a way to directly measure airway functional abnormalities; the clinical relevance of 129Xe MRI ventilation defects in ever-hospitalised and never-hospitalised patients who had COVID-19 has not been ascertained. It remains unclear if persistent symptoms beyond the infectious phase are related to small airways disease and ventilation heterogeneity. Hence, we measured 129Xe MRI ventilation defects, pulmonary function and symptoms in ever-hospitalised and never-hospitalised patients who had COVID-19 with persistent symptoms consistent with post-acute COVID-19 syndrome (PACS). METHODS Consenting participants with a confirmed diagnosis of PACS completed 129Xe MRI, CT, spirometry, multi-breath inert-gas washout, 6-minute walk test, St. George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (mMRC) dyspnoea scale, modified Borg scale and International Physical Activity Questionnaire. Consenting ever-COVID volunteers completed 129Xe MRI and pulmonary function tests only. RESULTS Seventy-six post-COVID and nine never-COVID participants were evaluated. Ventilation defect per cent (VDP) was abnormal and significantly greater in ever-COVID as compared with never-COVID participants (p<0.001) and significantly greater in ever-hospitalised compared with never-hospitalised participants who had COVID-19 (p=0.048), in whom diffusing capacity of the lung for carbon-monoxide (p=0.009) and 6-minute walk distance (6MWD) (p=0.005) were also significantly different. 129Xe MRI VDP was also related to the 6MWD (p=0.02) and post-exertional SpO2 (p=0.002). Participants with abnormal VDP (≥4.3%) had significantly worse 6MWD (p=0.003) and post-exertional SpO2 (p=0.03). CONCLUSION 129Xe MRI VDP was significantly worse in ever-hospitalised as compared with never-hospitalised participants and was related to 6MWD and exertional SpO2 but not SGRQ or mMRC scores. TRIAL REGISTRATION NUMBER NCT05014516.
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Affiliation(s)
- Harkiran K Kooner
- Robarts Research Institute, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Marrissa J McIntosh
- Robarts Research Institute, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Alexander M Matheson
- Robarts Research Institute, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Carmen Venegas
- Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Hamilton, Ontario, Canada.,Division of Respirology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Nisarg Radadia
- Division of Respirology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Terence Ho
- Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Hamilton, Ontario, Canada.,Division of Respirology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | | | - Norman B Konyer
- Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - Giles E Santyr
- The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Mitchell S Albert
- Department of Chemistry, Lakehead University, Thunder Bay, Ontario, Canada.,Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
| | - Alexei Ouriadov
- Department of Physics and Astronomy, Western University, London, Ontario, Canada
| | - Mohamed Abdelrazek
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Miranda Kirby
- Department of Physics, Ryerson University, Toronto, Ontario, Canada
| | - Inderdeep Dhaliwal
- Division of Respirology, Department of Medicine, Western University, London, Ontario, Canada
| | - J Michael Nicholson
- Division of Respirology, Department of Medicine, Western University, London, Ontario, Canada
| | - Parameswaran Nair
- Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Hamilton, Ontario, Canada.,Division of Respirology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Sarah Svenningsen
- Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Hamilton, Ontario, Canada.,Division of Respirology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Grace Parraga
- Robarts Research Institute, Western University, London, Ontario, Canada .,Department of Medical Biophysics, Western University, London, Ontario, Canada.,Division of Respirology, Department of Medicine, Western University, London, Ontario, Canada
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9
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Perron S, Ouriadov A, Wawrzyn K, Hickling S, Fox MS, Serrai H, Santyr G. Application of a 2D frequency encoding sectoral approach to hyperpolarized 129Xe MRI at low field. J Magn Reson 2022; 336:107159. [PMID: 35183921 DOI: 10.1016/j.jmr.2022.107159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 01/05/2022] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Inhaled hyperpolarized 129Xe MRI is a non-invasive and radiation risk free lung imaging method, which can directly measure the business unit of the lung where gas exchange occurs: the alveoli and acinar ducts (lung function). Currently, three imaging approaches have been demonstrated to be useful for hyperpolarized 129Xe MR in lungs: Fast Gradient Recalled Echo (FGRE), Radial Projection Reconstruction (PR), and spiral/cones. Typically, non-Cartesian acquisitions such as PR and spiral/cones require specific data post-processing, such as interpolating, regridding, and density-weighting procedures for image reconstruction, which often leads to smoothing effects and resolution degradation. On the other hand, Cartesian methods such as FGRE are not short-echo time (TE) methods; they suffer from imaging gradient-induced diffusion-weighting of the k-space center, and employ a significant number of radio-frequency (RF) pulses. Due to the non-renewable magnetization of the hyperpolarized media, the use of a large number of RF pulses (FGRE/PR) required for full k-space coverage is a significant limitation, especially for low field (<0.5 T) hyperpolarized gas MRI. We demonstrate an ultra-fast, purely frequency-encoded, Cartesian pulse sequence called Frequency-Encoding Sectoral (FES), which takes advantage of the long T2* of hyperpolarized 129Xe gas at low field strength (0.074 T). In contrast to PR/FGRE, it uses a much smaller number of RF pulses, and consequently maximizes image Signal-to-Noise Ratio (SNR) while shortening acquisition time. Additionally, FES does not suffer from non-uniform T2* decay leading to image blurring; a common issue with interleaved spirals/cones. The Cartesian k-space coverage of the proposed FES method does not require specific k-space data post-processing, unlike PR/FGRE and spiral/cones methods. Proton scans were used to compare the FES sequence to both FGRE and Phase Encoding Sectoral, in terms of their SNR values and imaging efficiency estimates. Using FES, proton and hyperpolarized 129Xe images were acquired from a custom hollow acrylic phantom (0.04L) and two normal rats (129Xe only), utilizing both single-breath and multiple-breath schemes. For the 129Xe phantom images, the apparent diffusion coefficient, T1, and T2* relaxation maps were acquired and generated. Blurring due to the T2* decay and B0 field variation were simulated to estimate dependence of the image resolution on the duration of the data acquisition windows (i.e. sector length), and temperature-induced resonance frequency shift from the low field magnet hardware.
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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, ON, Canada.
| | - Krzysztof Wawrzyn
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada
| | | | - Matthew S Fox
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada
| | - Hacene Serrai
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada
| | - Giles Santyr
- Translational Medicine Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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10
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Svenningsen S, McIntosh M, Ouriadov A, Matheson AM, Konyer NB, Eddy RL, McCormack DG, Noseworthy MD, Nair P, Parraga G. Reproducibility of Hyperpolarized 129Xe MRI Ventilation Defect Percent in Severe Asthma to Evaluate Clinical Trial Feasibility. Acad Radiol 2021; 28:817-826. [PMID: 32417033 DOI: 10.1016/j.acra.2020.04.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 04/07/2020] [Accepted: 04/15/2020] [Indexed: 02/06/2023]
Abstract
RATIONALE AND OBJECTIVES 129Xe MRI has been developed to noninvasively visualize and quantify the functional consequence of airway obstruction in asthma. Its widespread application requires evidence of intersite reproducibility and agreement. Our objective was to evaluate reproducibility and agreement of 129Xe ventilation MRI measurements in severe asthmatics at two sites. MATERIALS AND METHODS In seven adults with severe asthma, 129Xe ventilation MRI was acquired pre- and post-bronchodilator at two geographic sites within 24-hours. 129Xe MRI signal-to-noise ratio (SNR) was calculated and ventilation abnormalities were quantified as the whole-lung and slice-by-slice ventilation defect percent (VDP). Intraclass correlation coefficients (ICC) and Bland-Altman analysis were used to determine intersite 129Xe VDP reproducibility and agreement. RESULTS Whole-lung and slice-by-slice 129Xe VDP measured at both sites were correlated and reproducible (pre-bronchodilator: whole-lung ICC = 0.90, p = 0.005, slice-by-slice ICC = 0.78, p < 0.0001; post-bronchodilator: whole-lung ICC = 0.94, p < 0.0001, slice-by-slice ICC = 0.83, p < 0.0001) notwithstanding intersite differences in the 129Xe-dose-equivalent-volume (101 ± 15 mL site 1, 49 ± 6 mL site 2, p < 0.0001), gas-mixture (129Xe/4He site 1; 129Xe/N2 site 2) and SNR (40 ± 19 site 1, 23 ± 5 site 2, p = 0.02). Qualitative 129Xe gas distribution differences were observed between sites and slice-by-slice 129Xe VDP, but not whole-lung 129Xe VDP, was significantly lower at site 1 (pre-bronchodilator VDP: whole-lung bias = -3%, p > 0.99, slice-by-slice bias = -3%, p = 0.0001; post-bronchodilator VDP: whole-lung bias = -2%, p = 0.59, slice-by-slice-bias = -2%, p = 0.0003). CONCLUSION 129Xe MRI VDP at two different sites measured within 24-hours in the same severe asthmatics were correlated. Qualitative and quantitative intersite differences in 129Xe regional gas distribution and VDP point to site-specific variability that may be due to differences in gas-mixture composition or SNR.
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Affiliation(s)
- Sarah Svenningsen
- Firestone Institute for Respiratory Health, St. Joseph's Healthcare Hamilton, Hamilton, Canada; Department of Medicine, McMaster University, 50 Charlton Avenue East, Hamilton, Ontario, Canada L8N 4A6.
| | - Marrissa McIntosh
- Robarts Research Institute, Western University, London, Canada; Department of Medical Biophysics, Western University, London, Canada
| | - Alexei Ouriadov
- Department of Physics and Astronomy, Western University, London, Canada
| | - Alexander M Matheson
- Robarts Research Institute, Western University, London, Canada; Department of Medical Biophysics, Western University, London, Canada
| | - Norman B Konyer
- Imaging Research Centre, St. Joseph's Healthcare Hamilton, Hamilton, Canada
| | - Rachel L Eddy
- Robarts Research Institute, Western University, London, Canada; Department of Medical Biophysics, Western University, London, Canada
| | | | - Michael D Noseworthy
- Department of Electrical and Computer Engineering, McMaster University, Hamilton, Canada
| | - Parameswaran Nair
- Firestone Institute for Respiratory Health, St. Joseph's Healthcare Hamilton, Hamilton, Canada; Department of Medicine, McMaster University, 50 Charlton Avenue East, Hamilton, Ontario, Canada L8N 4A6
| | - Grace Parraga
- Robarts Research Institute, Western University, London, Canada; Department of Medical Biophysics, Western University, London, Canada; Department of Medicine, Western University, London, Canada
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11
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Ouriadov A, Guo F, McCormack DG, Parraga G. Accelerated 129 Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha-1 antitrypsin deficiency. Magn Reson Med 2019; 84:416-426. [PMID: 31765497 DOI: 10.1002/mrm.28091] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/21/2022]
Abstract
PURPOSE Multi-b diffusion-weighted hyperpolarized inhaled-gas MRI provides imaging biomarkers of terminal airspace enlargement including ADC and mean linear intercept (Lm ), but clinical translation has been limited because image acquisition requires relatively long or multiple breath-holds that are not well-tolerated by patients. Therefore, we aimed to accelerate single breath-hold 3D multi-b diffusion-weighted 129 Xe MRI, using k-space undersampling in imaging direction using a different undersampling pattern for different b-values combined with the stretched exponential model to generate maps of ventilation, apparent transverse relaxation time constant ( T 2 ∗ ), ADC, and Lm values in a single, short breath-hold; accelerated and non-accelerated measurements were directly compared. METHODS We evaluated multi-b (0, 12, 20, 30, and 45.5 s/cm2 ) diffusion-weighted 129 Xe T 2 ∗ /ADC/morphometry estimates using acceleration factor (AF = 1 and 7) and multi-breath sampling in 3 volunteers (HV), and 6 participants with alpha-1 antitrypsin deficiency (AATD). RESULTS For the HV subgroup, mean differences of 5%, 2%, and 8% were observed between fully sampled and undersampled k-space for ADC, Lm , and T 2 ∗ values, respectively. For the AATD subgroup, mean differences were 9%, 6%, and 12% between fully sampled and undersampled k-space for ADC, Lm and T 2 ∗ values, respectively. Although mean differences of 1% and 4.5% were observed between accelerated and multi-breath sampled ADC and Lm values, respectively, mean ADC/Lm estimates were not significantly different from corresponding mean ADCM /Lm M or mean ADCA /Lm A estimates (all P > 0.60 , A = undersampled and M = multi-breath sampled). CONCLUSIONS Accelerated multi-b diffusion-weighted 129 Xe MRI is feasible at AF = 7 for generating pulmonary ADC and Lm in AATD and normal lung.
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Affiliation(s)
- Alexei Ouriadov
- Department of Physics and Astronomy, The University of Western Ontario, London, Canada.,Lawson Health Research Institute, London, Canada
| | - Fumin Guo
- Sunnybrook Research Institute, University of Toronto, Toronto, Canada
| | - David G McCormack
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, Canada
| | - Grace Parraga
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, Canada.,Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
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12
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Westcott A, Guo F, Parraga G, Ouriadov A. Rapid single‐breath hyperpolarized noble gas MRI‐based biomarkers of airspace enlargement. J Magn Reson Imaging 2019. [DOI: 10.1002/jmri.26774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Andrew Westcott
- Robarts Research Institute, University of Western Ontario London Canada
- Department of Medical Biophysics University of Western Ontario London Canada
| | - Fumin Guo
- Robarts Research Institute, University of Western Ontario London Canada
- Sunnybrook Research Institute, University of Toronto Toronto Canada
| | - Grace Parraga
- Robarts Research Institute, University of Western Ontario London Canada
- Department of Medical Biophysics University of Western Ontario London Canada
| | - Alexei Ouriadov
- Robarts Research Institute, University of Western Ontario London Canada
- Department of Medical Biophysics University of Western Ontario London Canada
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13
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Westcott A, McCormack DG, Parraga G, Ouriadov A. Advanced pulmonary MRI to quantify alveolar and acinar duct abnormalities: Current status and future clinical applications. J Magn Reson Imaging 2019; 50:28-40. [PMID: 30637857 DOI: 10.1002/jmri.26623] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 12/23/2022] Open
Abstract
There are serious clinical gaps in our understanding of chronic lung disease that require novel, sensitive, and noninvasive in vivo measurements of the lung parenchyma to measure disease pathogenesis and progressive changes over time as well as response to treatment. Until recently, our knowledge and appreciation of the tissue changes that accompany lung disease has depended on ex vivo biopsy and concomitant histological and stereological measurements. These measurements have revealed the underlying pathologies that drive lung disease and have provided important observations about airway occlusion, obliteration of the terminal bronchioles and airspace enlargement, or fibrosis and their roles in disease initiation and progression. ex vivo tissue stereology and histology are the established gold standards and, more recently, micro-computed tomography (CT) measurements of ex vivo tissue samples has also been employed to reveal new mechanistic findings about the progression of obstructive lung disease in patients. While these approaches have provided important understandings using ex vivo analysis of excised samples, recently developed hyperpolarized noble gas MRI methods provide an opportunity to noninvasively measure acinar duct and terminal airway dimensions and geometry in vivo, and, without radiation burden. Therefore, in this review we summarize emerging pulmonary MRI morphometry methods that provide noninvasive in vivo measurements of the lung in patients with bronchopulmonary dysplasia and chronic obstructive pulmonary disease, among others. We discuss new findings, future research directions, as well as clinical opportunities to address current gaps in patient care and for testing of new therapies. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;50:28-40.
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Affiliation(s)
- Andrew Westcott
- Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
| | - David G McCormack
- Division of Respirology, Department of Medicine, University of Western Ontario, London, Canada
| | - Grace Parraga
- Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada.,Division of Respirology, Department of Medicine, University of Western Ontario, London, Canada
| | - Alexei Ouriadov
- Department of Physics and Astronomy, University of Western Ontario, London, Canada
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14
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Westcott A, Guo F, Parraga G, Ouriadov A. Rapid single-breath hyperpolarized noble gas MRI-based biomarkers of airspace enlargement. J Magn Reson Imaging 2018; 49:1713-1722. [PMID: 30578587 DOI: 10.1002/jmri.26574] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/28/2018] [Accepted: 10/29/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Multi-b diffusion-weighted hyperpolarized-gas MRI measures pulmonary airspace-enlargement using apparent diffusion coefficients (ADCs) and mean-linear-intercepts (Lm ). PURPOSE To develop single-breath 3D multi-b diffusion-weighted 3 He and 129 Xe MRI using k-space undersampling. Rapid, cost-efficient, single-breath acquisitions may facilitate clinical translation. STUDY TYPE Prospective. SUBJECTS We evaluated 12 participants, including nine subjects (mean age = 69 ± 9) who were included in the retrospective experiment and three chronic pulmonary obstruction disease (COPD) patients (mean age = 81 ± 6) who participated in the prospective study. FIELD STRENGTH A whole-body 3 T 2D/3D fast gradient recall echo (FGRE) sequence. ASSESSMENT Hyperpolarized 3 He/129 Xe MRI, spirometry, plethysmography computed tomography (CT). We evaluated 129 Xe ADC/morphometry estimates by retrospectively undersampling previously acquired fully sampled multibreath, multi-b diffusion-weighted data. Next, we prospectively evaluated the feasibility of accelerated (AF = 7) 3 He MRI static-ventilation/T2 * (extra short-TE, b = 0 image) and ADC/morphometry (five b-values) maps using a single gas-dose and 16-second breath-hold. To conservatively evaluate cost-improvement, we compared total costs of single vs. multiple 129 Xe doses. STATISTICAL TESTS Multivariate analysis of variance, independent t-tests and voxel-by-voxel basis difference test. RESULTS For the retrospectively undersampled 129 Xe data, a nonsignificant mean difference for ADC/Lm of 14%/12%, 12%/8%, and 11%/9% was observed (all, P > 0.4) between the fully sampled and accelerated data for the never-smoker, COPD, and alpha-1 antitrypsin deficiency (AATD) groups, respectively. The control never-smoker group had significantly lower ADC (P < 0.001) and Lm (P < 0.001) than the COPD/AATD group for both fully sampled and accelerated data. For the prospectively acquired 3 He MRI data, static-ventilation, T2 *, ADC, and morphometry maps were acquired using a single 16-second breath-hold scan and single gas dose. Accelerated imaging resulted in cost savings of ~$US 1000/patient, a conservative estimate based on 129 Xe MRI dose savings (single vs. five doses). DATA CONCLUSION This is a proof-of-concept demonstration of accelerated (7×) morphometry that shows that less cost- and time-efficient multibreath methods that lead to variability and patient fatigue may be avoided in the future. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018.
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Affiliation(s)
- Andrew Westcott
- Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
| | - Fumin Guo
- Robarts Research Institute, University of Western Ontario, London, Canada.,Sunnybrook Research Institute, University of Toronto, Toronto, Canada
| | - Grace Parraga
- Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
| | - Alexei Ouriadov
- Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
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15
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Westcott A, Capaldi DP, Ouriadov A, McCormack DG, Parraga G. Hyperpolarized 3
He MRI ventilatory apparent diffusion coefficient of alpha-1 antitrypsin deficiency. J Magn Reson Imaging 2018; 49:311-313. [DOI: 10.1002/jmri.26202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 01/20/2023] Open
Affiliation(s)
- Andrew Westcott
- Robarts Research Institute; Western University; London ON Canada
- Department of Medical Biophysics; Western University; London ON Canada
| | - Dante P.I. Capaldi
- Robarts Research Institute; Western University; London ON Canada
- Department of Medical Biophysics; Western University; London ON Canada
| | - Alexei Ouriadov
- Robarts Research Institute; Western University; London ON Canada
| | - David G. McCormack
- Division of Respirology, Department of Medicine; Western University; London ON Canada
| | - Grace Parraga
- Robarts Research Institute; Western University; London ON Canada
- Department of Medical Biophysics; Western University; London ON Canada
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16
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Lessard E, Young HM, Bhalla A, Pike D, Sheikh K, McCormack DG, Ouriadov A, Parraga G. Pulmonary 3He Magnetic Resonance Imaging Biomarkers of Regional Airspace Enlargement in Alpha-1 Antitrypsin Deficiency. Acad Radiol 2017. [PMID: 28645458 DOI: 10.1016/j.acra.2017.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RATIONALE AND OBJECTIVES Thoracic x-ray computed tomography (CT) and hyperpolarized 3He magnetic resonance imaging (MRI) provide quantitative measurements of airspace enlargement in patients with emphysema. For patients with panlobular emphysema due to alpha-1 antitrypsin deficiency (AATD), sensitive biomarkers of disease progression and response to therapy have been difficult to develop and exploit, especially those biomarkers that correlate with outcomes like quality of life. Here, our objective was to generate and compare CT and diffusion-weighted inhaled-gas MRI measurements of emphysema including apparent diffusion coefficient (ADC) and MRI-derived mean linear intercept (Lm) in patients with AATD, chronic obstructive pulmonary disease (COPD) ex-smokers, and elderly never-smokers. MATERIALS AND METHODS We enrolled patients with AATD (n = 8; 57 ± 7 years), ex-smokers with COPD (n = 8; 77 ± 6 years), and a control group of never-smokers (n = 5; 64 ± 2 years) who underwent thoracic CT, MRI, spirometry, plethysmography, the St. George's Respiratory Questionnaire, and the 6-minute walk test during a single 2-hour visit. MRI-derived ADC, Lm, surface-to-volume ratio, and ventilation defect percent were generated for the apical, basal, and whole lung as was CT lung area ≤-950 Hounsfield units (RA950), low attenuating clusters, and airway count. RESULTS In patients with AATD, there was a significantly different MRI-derived ADC (P = .03), Lm (P < .0001), and surface-to-volume ratio (P < .0001), but not diffusing capacity of carbon monoxide, residual volume or total lung capacity, or CT RA950 (P > .05) compared to COPD ex-smokers with a significantly different St. George's Respiratory Questionnaire. CONCLUSIONS In this proof-of-concept demonstration, we evaluated CT and MRI lung emphysema measurements and observed significantly worse MRI biomarkers of emphysema in patients with AATD compared to patients with COPD, although CT RA950 and diffusing capacity of carbon monoxide were not significantly different, underscoring the sensitivity of MRI measurements of AATD emphysema.
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Affiliation(s)
- Eric Lessard
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St North, London, ON, Canada N6A 5C1
| | - Heather M Young
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St North, London, ON, Canada N6A 5C1
| | - Anurag Bhalla
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7
| | - Damien Pike
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St North, London, ON, Canada N6A 5C1
| | - Khadija Sheikh
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St North, London, ON, Canada N6A 5C1
| | - David G McCormack
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, Ontario, Canada
| | - Alexei Ouriadov
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St North, London, ON, Canada N6A 5C1
| | - Grace Parraga
- Robarts Research Institute, 1151 Richmond Street North, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St North, London, ON, Canada N6A 5C1.
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17
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Ouriadov A, Lessard E, Sheikh K, Parraga G. Pulmonary MRI morphometry modeling of airspace enlargement in chronic obstructive pulmonary disease and alpha-1 antitrypsin deficiency. Magn Reson Med 2017; 79:439-448. [PMID: 28198571 DOI: 10.1002/mrm.26642] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/23/2022]
Abstract
PURPOSE We generated lung morphometry measurements using single-breath diffusion-weighted MRI and three different acinar duct models in healthy participants and patients with emphysema stemming from chronic obstructive lung disease (COPD) and alpha-1 antitrypsin deficiency (AATD). METHODS Single-breath-inhaled 3 He MRI with five diffusion sensitizations (b-value = 0, 1.6, 3.2, 4.8, and 6.4 s/cm2 ) was used, and signal intensities were fit using a cylindrical and single-compartment acinar-duct model to estimate MRI-derived mean linear intercept (Lm ) and surface-to-volume ratio (S/V). A stretched exponential model was also developed to estimate the mean airway length and Lm . RESULTS We evaluated 42 participants, including 15 elderly never-smokers (69 ± 5 years), 12 ex-smokers without COPD (67 ± 11 years), 9 COPD ex-smokers (80 ± 6 years), and 6 AATD patients (59 ± 6 years). In the never- and ex-smokers, the diffusing capacity of the lung for carbon monoxide (DLCO ) and computed tomography relative area of less than -950 Hounsfield units (RA950 ) were normal, but these were abnormal in the COPD and AATD patients, which is reflective of emphysema. Although cylindrical and stretched-exponential-model estimates of Lm and S/V were not significantly different, the single-compartment-model estimates were significantly different (P < 0.05) for the never- and ex-smoker subgroups. All models estimated significantly worse Lm and S/V in the AATD and COPD subgroups compared with the never- and ex-smokers without emphysema. CONCLUSIONS Differences in airspace enlargement may be estimated using Lm and S/V, generated using MRI and a stretched-exponential or cylindrical model of the acinar ducts. Magn Reson Med 79:439-448, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Alexei Ouriadov
- Robarts Research Institute, London, Canada.,Department of Medical Biophysics, the University of Western Ontario, London, Canada
| | - Eric Lessard
- Robarts Research Institute, London, Canada.,Department of Medical Biophysics, the University of Western Ontario, London, Canada
| | - Khadija Sheikh
- Robarts Research Institute, London, Canada.,Department of Medical Biophysics, the University of Western Ontario, London, Canada
| | - Grace Parraga
- Robarts Research Institute, London, Canada.,Department of Medical Biophysics, the University of Western Ontario, London, Canada
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18
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Sheikh K, Bhalla A, Ouriadov A, Young HM, Yamashita CM, Luu TM, Katz S, Parraga G. Pulmonary magnetic resonance imaging biomarkers of lung structure and function in adult survivors of bronchopulmonary dysplasia with COPD. Cogent Medicine 2017. [DOI: 10.1080/2331205x.2017.1282033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Khadija Sheikh
- Robarts Research Institute, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
- Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
| | - Anurag Bhalla
- Robarts Research Institute, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
| | - Alexei Ouriadov
- Robarts Research Institute, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
| | - Heather M. Young
- Robarts Research Institute, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
- Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
| | - Cory M. Yamashita
- Division of Respirology, Department of Medicine, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
| | - Thuy Mai Luu
- Department of Pediatrics, CHU Sainte Justine, Université de Montréal, Montréal, Canada
| | - Sherri Katz
- Children’s Hospital of Eastern Ontario, University of Ottawa, Ottawa, Canada
| | - Grace Parraga
- Robarts Research Institute, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
- Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond St, London, Canada N6A 5B7
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19
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Sheikh K, Guo F, Capaldi DPI, Ouriadov A, Eddy RL, Svenningsen S, Parraga G. Ultrashort echo time MRI biomarkers of asthma. J Magn Reson Imaging 2016; 45:1204-1215. [PMID: 27731948 DOI: 10.1002/jmri.25503] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/20/2016] [Indexed: 01/08/2023] Open
Abstract
PURPOSE To develop and assess ultrashort echo-time (UTE) magnetic resonance imaging (MRI) biomarkers of lung function in asthma patients. MATERIALS AND METHODS Thirty participants including 13 healthy volunteers and 17 asthmatics provided written informed consent to UTE and pulmonary function tests in addition to hyperpolarized-noble-gas 3T MRI and computed tomography (CT) for asthmatics only. The difference in MRI signal-intensity (SI) across four lung volumes (full-expiration, functional-residual-capacity [FRC], FRC+1L, and full-inspiration) was determined on a voxel-by-voxel basis to generate dynamic proton-density (DPD) maps. MRI ventilation-defect-percent (VDP), UTE SI, and DPD values as well as CT radiodensity were determined for whole lung and individual lobes. RESULTS Mean SI at full-expiration (P < 0.01), FRC (P < 0.05), and DPD (P < 0.01) were greater in healthy volunteers compared to asthmatics. In asthmatics, UTE SI at full-expiration and DPD were correlated with FEV1 /FVC (SI r = 0.73/P = 0.002; DPD r = 0.75/P = 0.003), RV/TLC (SI r = -0.57/P = 0.02), or RV (DPD r = -0.62/P = 0.02), CT radiodensity (SI r = 0.83/P = 0.006; DPD r = 0.71/P = 0.01), and lobar VDP (SI rs = -0.33/P = 0.02; DPD rs = -0.47/P = 0.01). CONCLUSION In patients with asthma, UTE SI and dynamic proton-density were related to pulmonary function measurements, whole lung and lobar VDP, as well as CT radiodensity. Thus, UTE MRI biomarkers may reflect ventilation heterogeneity and/or gas-trapping in asthmatics using conventional equipment, making this approach potentially amenable for clinical use. LEVEL OF EVIDENCE 2 J. Magn. Reson. Imaging 2017;45:1204-1215.
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Affiliation(s)
- Khadija Sheikh
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Fumin Guo
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Graduate Program in Biomedical Engineering, The University of Western Ontario, London, Canada
| | - Dante P I Capaldi
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Alexei Ouriadov
- Robarts Research Institute, The University of Western Ontario, London, Canada
| | - Rachel L Eddy
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Sarah Svenningsen
- Robarts Research Institute, The University of Western Ontario, London, Canada
| | - Grace Parraga
- Robarts Research Institute, The University of Western Ontario, London, Canada.,Department of Medical Biophysics, The University of Western Ontario, London, Canada.,Graduate Program in Biomedical Engineering, The University of Western Ontario, London, Canada
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20
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Pike D, Kirby M, Eddy RL, Guo F, Capaldi DPI, Ouriadov A, McCormack DG, Parraga G. Regional Heterogeneity of Chronic Obstructive Pulmonary Disease Phenotypes: Pulmonary (3)He Magnetic Resonance Imaging and Computed Tomography. COPD 2016; 13:601-9. [PMID: 26788765 DOI: 10.3109/15412555.2015.1123682] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pulmonary ventilation may be visualized and measured using hyperpolarized (3)He magnetic resonance imaging (MRI) while emphysema and its distribution can be quantified using thoracic computed tomography (CT). Our objective was to phenotype ex-smokers with COPD based on the apical-to-basal distribution of ventilation abnormalities and emphysema to better understand how these phenotypes change regionally as COPD progresses. We evaluated 100 COPD ex-smokers who provided written informed consent and underwent spirometry, CT and (3)He MRI. (3)He MRI ventilation imaging was used to quantify the ventilation defect percent (VDP) for whole-lung and individual lung lobes. Regional VDP was used to generate the apical-lung (AL)-to-basal-lung (BL) difference (ΔVDP); a positive ΔVDP indicated AL-predominant and negative ΔVDP indicated BL-predominant ventilation defects. Emphysema was quantified using the relative-area-of-the-lung ≤-950HU (RA950) of the CT density histogram for whole-lung and individual lung lobes. The AL-to-BL RA950 difference (ΔRA950) was generated with a positive ΔRA950 indicating AL-predominant emphysema and a negative ΔRA950 indicating BL-predominant emphysema. Seventy-two ex-smokers reported BL-predominant MRI ventilation defects and 71 reported AL-predominant CT emphysema. BL-predominant ventilation defects (AL/BL: GOLD I = 18%/82%, GOLD II = 24%/76%) and AL-predominant emphysema (AL/BL: GOLD I = 84%/16%, GOLD II = 72%/28%) were the major phenotypes in mild-moderate COPD. In severe COPD there was a more uniform distribution for ventilation defects (AL/BL: GOLD III = 40%/60%, GOLD IV = 43%/57%) and emphysema (AL/BL: GOLD III = 64%/36%, GOLD IV = 43%/57%). Basal-lung ventilation defects predominated in mild-moderate GOLD grades, and a more homogeneous distribution of ventilation defects was observed in more advanced grade COPD; these differences suggest that over time, regional ventilation abnormalities become more homogenously distributed during disease progression.
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Affiliation(s)
- Damien Pike
- a Robarts Research Institute, The University of Western Ontario , London , Canada.,b Department of Medical Biophysics , The University of Western Ontario , London , Canada
| | - Miranda Kirby
- c James Hogg Research Centre, St. Paul's Hospital, University of British Columbia , Vancouver , Canada
| | - Rachel L Eddy
- a Robarts Research Institute, The University of Western Ontario , London , Canada.,b Department of Medical Biophysics , The University of Western Ontario , London , Canada
| | - Fumin Guo
- a Robarts Research Institute, The University of Western Ontario , London , Canada.,d Graduate Program in Biomedical Engineering, The University of Western Ontario , London , Canada
| | - Dante P I Capaldi
- a Robarts Research Institute, The University of Western Ontario , London , Canada.,b Department of Medical Biophysics , The University of Western Ontario , London , Canada
| | - Alexei Ouriadov
- a Robarts Research Institute, The University of Western Ontario , London , Canada
| | - David G McCormack
- e Division of Respirology, Department of Medicine , The University of Western Ontario , London , Canada
| | - Grace Parraga
- a Robarts Research Institute, The University of Western Ontario , London , Canada.,b Department of Medical Biophysics , The University of Western Ontario , London , Canada.,d Graduate Program in Biomedical Engineering, The University of Western Ontario , London , Canada
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21
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Paulin GA, Ouriadov A, Lessard E, Sheikh K, McCormack DG, Parraga G. Noninvasive quantification of alveolar morphometry in elderly never- and ex-smokers. Physiol Rep 2015; 3:3/10/e12583. [PMID: 26462748 PMCID: PMC4632953 DOI: 10.14814/phy2.12583] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Diffusion-weighted magnetic resonance imaging (MRI) provides a way to generate in vivo lung images with contrast sensitive to the molecular displacement of inhaled gas at subcellular length scales. Here, we aimed to evaluate hyperpolarized 3He MRI estimates of the alveolar dimensions in 38 healthy elderly never-smokers (73 ± 6 years, 15 males) and 21 elderly ex-smokers (70 ± 10 years, 14 males) with (n = 8, 77 ± 6 years) and without emphysema (n = 13, 65 ± 10 years). The ex-smoker and never-smoker subgroups were significantly different for FEV1/FVC (P = 0.0001) and DLCO (P = 0.009); while ex-smokers with emphysema reported significantly diminished FEV1/FVC (P = 0.02) and a trend toward lower DLCO (P = 0.05) than ex-smokers without emphysema. MRI apparent diffusion coefficients (ADC) and CT measurements of emphysema (relative area–CT density histogram, RA950) were significantly different (P = 0.001 and P = 0.007) for never-smoker and ex-smoker subgroups. In never-smokers, the MRI estimate of mean linear intercept (260 ± 27 μm) was significantly elevated as compared to the results previously reported in younger never-smokers (210 ± 30 μm), and trended smaller than in the age-matched ex-smokers (320 ± 72 μm, P = 0.06) evaluated here. Never-smokers also reported significantly smaller internal (220 ± 24 μm, P = 0.01) acinar radius but greater alveolar sheath thickness (120 ± 4 μm, P < 0.0001) than ex-smokers. Never-smokers were also significantly different than ex-smokers without emphysema for alveolar sheath thickness but not ADC, while ex-smokers with emphysema reported significantly different ADC but not alveolar sheath thickness compared to ex-smokers without CT evidence of emphysema. Differences in alveolar measurements in never- and ex-smokers demonstrate the sensitivity of MRI measurements to the different effects of smoking and aging on acinar morphometry.
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Affiliation(s)
- Gregory A Paulin
- Imaging Research Laboratories, Robarts Research Institute The University of Western Ontario, London, Ontario, Canada Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
| | - Alexei Ouriadov
- Imaging Research Laboratories, Robarts Research Institute The University of Western Ontario, London, Ontario, Canada
| | - Eric Lessard
- Imaging Research Laboratories, Robarts Research Institute The University of Western Ontario, London, Ontario, Canada Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
| | - Khadija Sheikh
- Imaging Research Laboratories, Robarts Research Institute The University of Western Ontario, London, Ontario, Canada Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
| | - David G McCormack
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, Ontario, Canada
| | - Grace Parraga
- Imaging Research Laboratories, Robarts Research Institute The University of Western Ontario, London, Ontario, Canada Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
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22
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Ouriadov A, Fox M, Hegarty E, Parraga G, Wong E, Santyr GE. Early stage radiation-induced lung injury detected using hyperpolarized (129) Xe Morphometry: Proof-of-concept demonstration in a rat model. Magn Reson Med 2015; 75:2421-31. [PMID: 26154889 DOI: 10.1002/mrm.25825] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 05/27/2015] [Accepted: 06/08/2015] [Indexed: 11/08/2022]
Abstract
PURPOSE Radiation-induced lung injury (RILI) is still the major dose-limiting toxicity related to lung cancer radiation therapy, and it is difficult to predict and detect patients who are at early risk of severe pneumonitis and fibrosis. The goal of this proof-of-concept preclinical demonstration was to investigate the potential of hyperpolarized (129) Xe diffusion-weighted MRI to detect the lung morphological changes associated with early stage RILI. METHODS Hyperpolarized (129) Xe MRI was performed using eight different diffusion sensitizations (0.0-115 s/cm(2) ) in a small group of control rats (n = 4) and rats 2 wk after radiation exposure (n = 5). The diffusion-weighted images were used to obtain morphological estimates of the pulmonary parenchyma including external radius (R), internal radius (r), alveolar sleeve depth (h), and mean airspace chord length (Lm ). The histological mean linear intercept (MLI) were obtained for five control and five irradiated animals. RESULTS Mean R, r, and Lm were both significantly different (P < 0.02) in the irradiated rats (74 ± 17 µm, 43 ± 12 µm, and 54 ± 17 µm, respectively) compared with the control rats (100 ± 12 µm, 67 ± 10 µm, and 79 ± 12 µm, respectively). Changes in measured Lm values were consistent with changes in MLI values observed by histology. CONCLUSIONS Hyperpolarized (129) Xe MRI provides a way to detect and measure regional microanatomical changes in lung parenchyma in a preclinical model of RILI. Magn Reson Med 75:2421-2431, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Alexei Ouriadov
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada
| | - Matthew Fox
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Elaine Hegarty
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada
| | - Grace Parraga
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Eugene Wong
- Department of Medical Biophysics, Western University, London, Ontario, Canada.,Department of Physics and Astronomy, Western University, London, Ontario, Canada
| | - Giles E Santyr
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada.,Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
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23
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Ouriadov A, Farag A, Kirby M, McCormack DG, Parraga G, Santyr GE. Pulmonary hyperpolarized (129) Xe morphometry for mapping xenon gas concentrations and alveolar oxygen partial pressure: Proof-of-concept demonstration in healthy and COPD subjects. Magn Reson Med 2014; 74:1726-32. [PMID: 25483611 DOI: 10.1002/mrm.25550] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 11/03/2014] [Accepted: 11/05/2014] [Indexed: 12/25/2022]
Abstract
PURPOSE Diffusion-weighted (DW) hyperpolarized (129) Xe morphometry magnetic resonance imaging (MRI) can be used to map regional differences in lung tissue micro-structure. We aimed to generate absolute xenon concentration ([Xe]) and alveolar oxygen partial pressure (pA O2 ) maps by extracting the unrestricted diffusion coefficient (D0 ) of xenon as a morphometric parameter. METHODS In this proof-of-concept demonstration, morphometry was performed using multi b-value (0, 12, 20, 30 s/cm(2) ) DW hyperpolarized (129) Xe images obtained in four never-smokers and four COPD ex-smokers. Morphometric parameters and D0 maps were computed and the latter used to generate [Xe] and pA O2 maps. Xenon concentration phantoms estimating a range of values mimicking those observed in vivo were also investigated. RESULTS Xenon D0 was significantly increased (P = 0.035) in COPD (0.14 ± 0.03 cm(2) /s) compared with never-smokers (0.12 ± 0.02 cm(2) /s). COPD ex-smokers also had significantly decreased [Xe] (COPD = 8 ± 7% versus never-smokers = 13 ± 8%, P = 0.012) and increased pA O2 (COPD = 18 ± 3% versus never-smokers = 15 ± 3%, P = 0.009) compared with never-smokers. Phantom measurements showed the expected dependence of D0 on [Xe] over the range of concentrations anticipated in vivo. CONCLUSION DW hyperpolarized (129) Xe MRI morphometry can be used to simultaneously map [Xe] and pA O2 in addition to providing micro-structural biomarkers of emphysematous destruction in COPD. Phantom measurements of D0 ([Xe]) supported the hypotheses that differences in subjects may reflect differences in functional residual capacity.
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Affiliation(s)
- A Ouriadov
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Canada
| | - A Farag
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Canada
| | - M Kirby
- Department of Medical Biophysics, Western University, London, Canada.,James Hogg Research Centre, The University of British Columbia, and The Institute of Heart and Lung Health, St. Paul's Hospital, Vancouver, Canada
| | - D G McCormack
- Department of Medicine, Western University, London, Canada
| | - G Parraga
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Canada.,Department of Medical Biophysics, Western University, London, Canada.,Department of Medical Imaging, Western University, London, Canada Western University, London, Canada
| | - G E Santyr
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Canada.,Department of Medical Biophysics, Western University, London, Canada.,Department of Medical Imaging, Western University, London, Canada Western University, London, Canada.,Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Canada
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24
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Santyr G, Fox M, Thind K, Hegarty E, Ouriadov A, Jensen M, Scholl TJ, Van Dyk J, Wong E. Anatomical, functional and metabolic imaging of radiation-induced lung injury using hyperpolarized MRI. NMR Biomed 2014; 27:1515-1524. [PMID: 25156928 DOI: 10.1002/nbm.3180] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 07/02/2014] [Accepted: 07/08/2014] [Indexed: 06/03/2023]
Abstract
MRI of hyperpolarized (129)Xe gas and (13)C-enriched substrates (e.g. pyruvate) presents an unprecedented opportunity to map anatomical, functional and metabolic changes associated with lung injury. In particular, inhaled hyperpolarized (129)Xe gas is exquisitely sensitive to changes in alveolar microanatomy and function accompanying lung inflammation through decreases in the apparent diffusion coefficient (ADC) of alveolar gas and increases in the transfer time (T(tr)) of xenon exchange from the gas and into the dissolved phase in the lung. Furthermore, metabolic changes associated with hypoxia arising from lung injury may be reflected by increases in lactate-to-pyruvate signal ratio obtained by magnetic resonance spectroscopic imaging following injection of hyperpolarized [1-(13)C]pyruvate. In this work, the application of hyperpolarized (129)Xe and (13)C MRI to radiation-induced lung injury (RILI) is reviewed and results of ADC, T(tr) and lactate-to-pyruvate signal ratio changes in a rat model of RILI are summarized. These results are consistent with conventional functional (i.e. blood gases) and histological (i.e. tissue density) changes, and correlate significantly with inflammatory cell counts (i.e. macrophages). Hyperpolarized MRI may provide an earlier indication of lung injury associated with radiotherapy of thoracic tumors, potentially allowing adjustment of treatment before the onset of severe complications and irreversible fibrosis.
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Affiliation(s)
- Giles Santyr
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Medical Imaging, Western University, London, Ontario, Canada; Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
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25
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Kirby M, Ouriadov A, Svenningsen S, Owrangi A, Wheatley A, Etemad‐Rezai R, Santyr GE, McCormack DG, Parraga G. Hyperpolarized 3He and 129Xe magnetic resonance imaging apparent diffusion coefficients: physiological relevance in older never- and ex-smokers. Physiol Rep 2014; 2:e12068. [PMID: 25347853 PMCID: PMC4187551 DOI: 10.14814/phy2.12068] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 05/30/2014] [Accepted: 06/04/2014] [Indexed: 11/24/2022] Open
Abstract
Noble gas pulmonary magnetic resonance imaging (MRI) is transitioning away from (3)He to (129)Xe gas, but the physiological/clinical relevance of (129)Xe apparent diffusion coefficient (ADC) parenchyma measurements is not well understood. Therefore, our objective was to generate (129)Xe MRI ADC for comparison with (3)He ADC and with well-established measurements of alveolar structure and function in older never-smokers and ex-smokers with chronic obstructive pulmonary disease (COPD). In four never-smokers and 10 COPD ex-smokers, (3)He (b = 1.6 sec/cm(2)) and (129)Xe (b = 12, 20, and 30 sec/cm(2)) ADC, computed tomography (CT) density-threshold measurements, and the diffusing capacity for carbon monoxide (DLCO) were measured. To understand regional differences, the anterior-posterior (APG) and superior-inferior (∆SI) ADC differences were evaluated. Compared to never-smokers, COPD ex-smokers showed greater (3)He ADC (P = 0.006), (129)Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.006), but not for ADCb30 (P > 0.05). Never-smokers and COPD ex-smokers had significantly different APG for (3)He ADC (P = 0.02), (129)Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.01), but not for ADCb30 (P > 0.05). ∆SI for never- and ex-smokers was significantly different for (3)He ADC (P = 0.046), but not for (129)Xe ADC (P > 0.05). There were strong correlations for DLCO with (3)He ADC and (129)Xe ADCb12 (both r = -0.95, P < 0.05); in a multivariate model (129)Xe ADCb12 was the only significant predictor of DLCO (P = 0.049). For COPD ex-smokers, CT relative area <-950 HU (RA950) correlated with (3)He ADC (r = 0.90, P = 0.008) and (129)Xe ADCb12 (r = 0.85, P = 0.03). In conclusion, while (129)Xe ADCb30 may be appropriate for evaluating subclinical or mild emphysema, in this small group of never-smokers and ex-smokers with moderate-to-severe emphysema, (129)Xe ADCb12 provided a physiologically appropriate estimate of gas exchange abnormalities and alveolar microstructure.
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Affiliation(s)
- Miranda Kirby
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
| | - Alexei Ouriadov
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
| | - Sarah Svenningsen
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
| | - Amir Owrangi
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
- Graduate Program in Biomedical Engineering, The University of Western Ontario, London, Ontario, Canada
| | - Andrew Wheatley
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
| | - Roya Etemad‐Rezai
- Department of Medical Imaging, The University of Western Ontario, London, Ontario, Canada
| | - Giles E. Santyr
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
| | - David G. McCormack
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, Ontario, Canada
| | - Grace Parraga
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada
- Graduate Program in Biomedical Engineering, The University of Western Ontario, London, Ontario, Canada
- Department of Medical Imaging, The University of Western Ontario, London, Ontario, Canada
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26
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Fox MS, Ouriadov A, Thind K, Hegarty E, Wong E, Hope A, Santyr GE. Detection of radiation induced lung injury in rats using dynamic hyperpolarized 129
Xe magnetic resonance spectroscopy. Med Phys 2014; 41:072302. [DOI: 10.1118/1.4881523] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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27
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Fox MS, Ouriadov A, Santyr GE. Comparison of hyperpolarized 3
He and 129
Xe MRI for the measurement of absolute ventilated lung volume in rats. Magn Reson Med 2013; 71:1130-6. [DOI: 10.1002/mrm.24746] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Matthew S. Fox
- Department of Physics and Astronomy; Western University; London Canada
- Imaging Research Laboratories; Robarts Research Institute, Western University; London Canada
| | - Alexei Ouriadov
- Imaging Research Laboratories; Robarts Research Institute, Western University; London Canada
| | - Giles E. Santyr
- Imaging Research Laboratories; Robarts Research Institute, Western University; London Canada
- Depts. of Medical Biophysics and Medical Imaging; Western University; London Canada
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28
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Ouriadov A, Farag A, Kirby M, McCormack DG, Parraga G, Santyr GE. Lung morphometry using hyperpolarized 129
Xe apparent diffusion coefficient anisotropy in chronic obstructive pulmonary disease. Magn Reson Med 2013; 70:1699-706. [DOI: 10.1002/mrm.24595] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 11/19/2012] [Accepted: 11/20/2012] [Indexed: 12/27/2022]
Affiliation(s)
- Alexei Ouriadov
- Ph.D., Imaging Research Laboratories; Robarts Research Institute; Western University, London Ontario Canada
| | - Adam Farag
- Ph.D., Imaging Research Laboratories; Robarts Research Institute; Western University, London Ontario Canada
| | - Miranda Kirby
- Ph.D., Imaging Research Laboratories; Robarts Research Institute; Western University, London Ontario Canada
- Department of Medical Biophysics; Western University; London Ontario Canada
| | | | - Grace Parraga
- Ph.D., Imaging Research Laboratories; Robarts Research Institute; Western University, London Ontario Canada
- Department of Medical Biophysics; Western University; London Ontario Canada
- Department of Medical Imaging; Western University; London Ontario Canada
| | - Giles E. Santyr
- Ph.D., Imaging Research Laboratories; Robarts Research Institute; Western University, London Ontario Canada
- Department of Medical Biophysics; Western University; London Ontario Canada
- Department of Medical Imaging; Western University; London Ontario Canada
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Kirby M, Svenningsen S, Owrangi A, Wheatley A, Farag A, Ouriadov A, Santyr GE, Etemad-Rezai R, Coxson HO, McCormack DG, Parraga G. Hyperpolarized3He and129Xe MR Imaging in Healthy Volunteers and Patients with Chronic Obstructive Pulmonary Disease. Radiology 2012; 265:600-10. [DOI: 10.1148/radiol.12120485] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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30
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Thind K, Chen A, Friesen-Waldner L, Ouriadov A, Scholl TJ, Fox M, Wong E, VanDyk J, Hope A, Santyr G. Detection of radiation-induced lung injury using hyperpolarized (13)C magnetic resonance spectroscopy and imaging. Magn Reson Med 2012; 70:601-9. [PMID: 23074042 DOI: 10.1002/mrm.24525] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 09/15/2012] [Accepted: 09/17/2012] [Indexed: 01/24/2023]
Abstract
Radiation-induced lung injury limits radiotherapy of thoracic cancers. Detection of radiation pneumonitis associated with early radiation-induced lung injury (2-4 weeks postirradiation) may provide an opportunity to adjust treatment, before the onset of acute pneumonitis and/or irreversible fibrosis. In this study, localized magnetic resonance (MR) spectroscopy and imaging of hyperpolarized (13)C-pyruvate (pyruvate) and (13)C-lactate (lactate) were performed in the thorax and kidney regions of rats 2 weeks following whole-thorax irradiation (14 Gy). Lactate-to-pyruvate signal ratio was observed to increase by 110% (P < 0.01), 57% (P < 0.02), and 107% (P < 0.01), respectively, in the thorax, lung, and heart tissues of the radiated rats compared with healthy age-matched rats. This was consistent with lung inflammation confirmed using cell micrographs of bronchioalveolar lavage specimens and decreases in arterial oxygen partial pressure (paO2), indicative of hypoxia. No statistically significant difference was observed in either lactate-to-pyruvate signal ratios in the kidney region (P = 0.50) between the healthy (0.215 ± 0.100) and radiated cohorts (0.215 ± 0.054) or in blood lactate levels (P = 0.69) in the healthy (1.255 ± 0.247 mmol/L) and the radiated cohorts (1.325 ± 0.214 mmol/L), confirming that the injury is localized to the thorax. This work demonstrates the feasibility of hyperpolarized (13)C metabolic MR spectroscopy and imaging for detection of early radiation-induced lung injury.
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Affiliation(s)
- K Thind
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada; Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
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Couch MJ, Ouriadov A, Santyr GE. Regional ventilation mapping of the rat lung using hyperpolarized129Xe magnetic resonance imaging. Magn Reson Med 2012; 68:1623-31. [DOI: 10.1002/mrm.24152] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 11/17/2011] [Accepted: 12/14/2011] [Indexed: 11/11/2022]
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Santyr GE, Couch MJ, Lam WW, Ouriadov A, Drangova M, McCormack DG, Holdsworth DW. Comparison of hyperpolarized (3)He MRI with Xe-enhanced computed tomography imaging for ventilation mapping of rat lung. NMR Biomed 2011; 24:1073-1080. [PMID: 21274963 DOI: 10.1002/nbm.1659] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 11/16/2010] [Accepted: 12/02/2010] [Indexed: 05/30/2023]
Abstract
Lung ventilation was mapped in five healthy Brown Norway rats (210-377 g) using both hyperpolarized (3)He MRI and Xe-enhanced computed tomography (Xe-CT) under similar ventilator conditions. Whole-lung measurements of ventilation r obtained with (3)He MRI were not significantly different from those obtained from Xe-CT (p = 0.1875 by Wilcoxon matched pairs test). The ventilation parameter r is defined as the fraction of refreshed gas per unit volume per breath. Regional ventilation was also measured in four regions of the lung using both methods. A two-tailed paired t-test was performed for each region, yielding p > 0.05 for all but the upper portion of the right lung. The distribution of regional ventilation was evaluated by calculating ventilation gradients in the superior/inferior (S/I) direction. The average S/I gradient obtained using the (3)He MRI method was found to be 0.17 ± 0.04 cm(-1) , whereas the average S/I gradient obtained using the Xe-CT method was found to be 0.016 ± 0.005 cm(-1) . In general, S/I ventilation gradients obtained from both methods were significantly different from each other (p = 0.0019 by two-tailed paired t-test). These regional differences in ventilation measurements may be caused by the manner in which the gas contrast agents distribute physiologically and/or by the imaging modality.
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Affiliation(s)
- Giles E Santyr
- Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada.
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Xu X, Boudreau M, Ouriadov A, Santyr GE. Mapping of (3) He apparent diffusion coefficient anisotropy at sub-millisecond diffusion times in an elastase-instilled rat model of emphysema. Magn Reson Med 2011; 67:1146-53. [PMID: 22135238 DOI: 10.1002/mrm.23098] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 05/25/2011] [Accepted: 06/21/2011] [Indexed: 01/08/2023]
Abstract
Hyperpolarized (3) He gas can provide detailed anatomical maps of the macroscopic airways in the lungs (i.e., ventilation) as well as insight into the lung microstructure through the apparent diffusion coefficient. In particular, the apparent diffusion coefficient of (3) He in the lung exhibits anisotropic effects that depend on diffusion time (δ), and it has been shown to be extraordinarily sensitive to enlargement in terminal airways and alveoli associated with emphysema. In this study, the anisotropic nature of the (3) He apparent diffusion coefficient is studied in a rat model of emphysema, based on elastase instillation, specifically for δ values less than one millisecond. Longitudinal (D(L) ) and transverse (D(T) ) diffusion coefficients were mapped at δ = 360 μs and δ = 800 μs based on a cylinder model of lung structure and correlated with histological measurement of alveolar damage based on mean linear intercept (L(m) ). Whole-lung mean D(T) measured at δ = 360 μs in the elastase-instilled rat lungs (0.14 ± 0.09 cm(2) /s) demonstrated the most significant increase (p = 0.00195) compared to the sham-instilled cohort (0.06 ± 0.06 cm(2) /s) and had a strong linear correlation with L(m) (Pearson's correlation coefficient of 0.9). These results suggest that measurement of (3) He apparent diffusion coefficient anisotropy, specifically D(T) , can provide a sensitive indicator of emphysema, particularly at very short diffusion times (δ = 360 μs).
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Affiliation(s)
- Xiaojun Xu
- Robarts Research Institute, London, Ontario, Canada.
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Thind K, Ouriadov A, Feiesen-Waldner L, Chen A, Scholl T, Fox M, Wong E, VanDyk J, Hill R, Hope A, Santyr G. TU-A-BRC-06: Using Hyperpolarized 13C Magnetic Resonance Spectroscopy to Detect Radiation Induced Lung Injury at an Early Stage. Med Phys 2011. [DOI: 10.1118/1.3613082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dominguez-Viqueira W, Ouriadov A, O'Halloran R, Fain SB, Santyr GE. Signal-to-noise ratio for hyperpolarized ³He MR imaging of human lungs: a 1.5 T and 3 T comparison. Magn Reson Med 2011; 66:1400-4. [PMID: 21523821 DOI: 10.1002/mrm.22920] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 01/21/2011] [Accepted: 02/18/2011] [Indexed: 11/08/2022]
Abstract
The signal-to-noise ratio in hyperpolarized noble gas MR imaging is expected to be independent of field strength at frequencies typical of clinical systems (e.g., 1.5 T), where body noise dominates over coil noise. Furthermore, at higher fields (e.g., 3 T), the SNR of lung images may decline due to decreases in T(2) originating from increases in susceptibility-induced field gradients at the air-tissue interface. In this work, the SNR of hyperpolarized (3) He lung imaging at two commonly used clinical field strengths (1.5 T and 3 T) were compared in the same volunteers. Thermally polarized and hyperpolarized (3) He phantoms were used to account for differences in MR imaging system and (3) He polarizer performance, respectively, at the two field strengths. After correcting for T(2) values measured at 1.5 T (16 ± 2 ms) and 3 T (7 ± 1 ms), no significant difference in image SNR between the two field strengths was observed, consistent with theory.
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Boudreau M, Kraayvanger R, Xu X, Ouriadov A, Santyr G. Sci-Fri AM: Imaging - 01: Measurement of Ultra-Short and Long-Range 3
He Apparent Diffusion Coefficients in an Elastase-Induced Rat Model of Emphysema. Med Phys 2010. [DOI: 10.1118/1.3476180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Santyr GE, Lam WW, Ouriadov A. Rapid and efficient mapping of regional ventilation in the rat lung using hyperpolarized 3He with Flip Angle Variation for Offset of RF and Relaxation (FAVOR). Magn Reson Med 2008; 59:1304-10. [PMID: 18506796 DOI: 10.1002/mrm.21582] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel imaging method is presented, Flip Angle Variation for Offset of RF and Relaxation (FAVOR), for rapid and efficient measurement of rat lung ventilation using hyperpolarized helium-3 (3He) gas. The FAVOR technique utilizes variable flip angles to remove the cumulative effect of RF pulses and T1 relaxation on the hyperpolarized gas signal and thereby eliminates the need for intervening air wash-out breaths and multiple cycles of 3He wash-in breaths before each image. The former allows an improvement in speed (by a factor of approximately 30) while the latter reduces the cost of each measurement (by a factor of approximately 5). The FAVOR and conventional ventilation methods were performed on six healthy male Brown Norway rats (190-270 g). Lobar measurements of ventilation, r, obtained with the FAVOR method were not significantly different from those obtained with the conventional method for the right middle and caudal and left lobes (P>0.05 by a Wilcoxon matched pairs test). A methacholine challenge test was also administered to an animal and reduction and recovery of r was detected by the FAVOR method. The reduced 3He consumption and the improvement in speed provided by FAVOR suggest that it may allow measurement of ventilation in human subjects not previously possible.
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Affiliation(s)
- Giles E Santyr
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.
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Mathew L, Evans A, Ouriadov A, Etemad-Rezai R, Fogel R, Santyr G, McCormack DG, Parraga G. Hyperpolarized 3He magnetic resonance imaging of chronic obstructive pulmonary disease: reproducibility at 3.0 tesla. Acad Radiol 2008; 15:1298-311. [PMID: 18790402 DOI: 10.1016/j.acra.2008.04.019] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 04/21/2008] [Accepted: 04/21/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVES We assessed subjects with stage II and stage III chronic obstructive pulmonary disease (COPD) and age-matched healthy volunteers at a single center using (3)He magnetic resonance imaging (MRI) at 3.0 T. Measurements of the (3)He apparent diffusion coefficient (ADC) and center coronal slice (3)He ventilation defect volume (VDV) were examined for same-day and 7-day reproducibility as well as subgroup comparisons. MATERIALS AND METHODS Twenty-four subjects who provided written informed consent (15 males; mean age 67 +/-7 years) with stage II (n = 9), stage III COPD (n = 7), and age-matched healthy volunteers (n = 8) were enrolled based on their age and pulmonary function test results. All subjects underwent plethysmography, spirometry, and MRI at 3.0 T. The time frame between scans was 7 +/- 2 minutes (same-day rescan) and again 7 +/- 2 days later (7-day rescan). (3)He ADC and VDV reproducibility was evaluated using linear regression, intraclass correlation coefficients (ICC) and Lin's concordance correlation coefficients (CCC). RESULTS ADC reproducibility was high for same-day rescan (r(2) = 0.934) and 7-day rescan (r(2) = 0.960, ICC and CCC of 0.96 and 0.98, respectively). Same-day rescan VDV reproducibility evaluated using the ICC and CCC (0.97 and 0.98, respectively) as well as linear regression (r(2) = 0.941) was also high, but VDV 7-day rescan reproducibility was lower and significantly different (r(2) = 0.576, P < .001, ICC 0.74, CCC 0.75, P < .01). CONCLUSIONS Hyperpolarized (3)He MRI was well-tolerated in subjects with stage II and stage III COPD. Seven-day repeated scanning was highly reproducible for ADC and moderately reproducible for VDV.
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Parra-Robles J, Dominguez Viqueira W, Xu X, Ouriadov A, Santyr GE. Theoretical prediction and experimental measurement of the field dependence of the apparent transverse relaxation of hyperpolarized noble gases in lungs. J Magn Reson 2008; 192:85-91. [PMID: 18358755 DOI: 10.1016/j.jmr.2008.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2007] [Revised: 02/01/2008] [Accepted: 02/04/2008] [Indexed: 05/26/2023]
Abstract
In this work, computer modeling based on a finite element method is used to simulate the T2* relaxation of hyperpolarized noble gases (HNG) in the lungs. A physical model of lung airways consisting of a phantom constructed from micro-capillary fibers of diameters similar to the size of lung airways with semi-permeable walls is also presented. The fibers are surrounded by a liquid medium (water) of magnetic susceptibility similar to lung tissue. Theoretical predictions of the field strength dependence of T2* for 129Xe in the phantom and in vivo rat lung are presented. These predictions are in good agreement with experimental T2* values obtained from the phantoms and in vivo rat lungs (160, 19 and 8 ms) at three different field strengths (0.074, 1.89 and 3T, respectively) using hyperpolarized 129Xe. The strong dependence of T2* on field strength is consistent with the theoretical prediction that low fields may be optimal for HNG MR imaging of the lungs as the decreased T2* at high fields necessitates an increase in bandwidth for conventional MR imaging.
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Affiliation(s)
- Juan Parra-Robles
- Imaging Research Laboratories, Robarts Research Institute, P.O. Box 5015, 100 Perth Drive, London, Ont., Canada N6A 5K8
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Parraga G, Ouriadov A, Evans A, McKay S, Lam WW, Fenster A, Etemad-Rezai R, McCormack D, Santyr G. Hyperpolarized 3He Ventilation Defects and Apparent Diffusion Coefficients in Chronic Obstructive Pulmonary Disease. Invest Radiol 2007; 42:384-91. [PMID: 17507809 DOI: 10.1097/01.rli.0000262571.81771.66] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Hyperpolarized 3He magnetic resonance imaging (3He MRI) at 3.0 Tesla of healthy volunteers and chronic obstructive pulmonary disease (COPD) patients was performed for quantitative evaluation of ventilation defects and apparent diffusion coefficients (ADC) and for comparison to published results acquired at 1.5 Tesla. The reproducibility of 3He ADC and ventilation defects was also assessed in subjects scanned 3 times, twice within 10 minutes, and again within 7 +/- 2 days of the first MRI visit. MATERIALS AND METHODS Hyperpolarized 3He MRI was performed in 6 subjects. Two interleaved images with and without additional diffusion sensitization were acquired with the first image serving as a ventilation image from which defect score and volume were measured and the combination of the 2 images used to compute ADC maps and ADC histograms. RESULTS He MRI at 3.0 Tesla showed increased mean ADC and ADC standard deviation for subjects with COPD compared with healthy volunteers (ADC healthy volunteer (0.24 +/- 0.12 cm2/s), mild-moderate COPD (0.34 +/- 0.14 cm2/s), and severe COPD (0.47 +/- 0.21 cm2/s), and these values were similar to previously reported results acquired at 1.5 Tesla. Reproducibility of mean ADC was high (coefficient of variation 2% in severe COPD, 3% in mild-moderate COPD, 4% in healthy volunteers) across all 3 scans. Higher same-day scan reproducibility was observed for ventilation defect volume compared with 1-week scan reproducibility in this small group of subjects. CONCLUSIONS ADC values for emphysematous lungs were significantly increased compared with healthy lungs in age-matched subjects, and all values were comparable to those reported previously at 1.5 Tesla. Ventilation defect score and ventilation defect volume results were also comparable to results previously reported in COPD subjects Reproducibility of ADC for same-day scan-rescan and 7-day rescan was high and similar to previously reported results.
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Affiliation(s)
- Grace Parraga
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.
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Evans A, McCormack D, Ouriadov A, Etemad-Rezai R, Santyr G, Parraga G. Anatomical distribution of3He apparent diffusion coefficients in severe chronic obstructive pulmonary disease. J Magn Reson Imaging 2007; 26:1537-47. [DOI: 10.1002/jmri.21205] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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McKay S, McCormack D, Etemad-Rezai R, Lam W, Ouriadov A, Santyr G, Parraga G. Po-Thur Eve General-23: 3He MRI Phenotypes of Lung in Phantoms and Healthy Volunteers. Med Phys 2006. [DOI: 10.1118/1.2244650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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