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Amzajerdian F, Hamedani H, Baron R, Loza L, Duncan I, Ruppert K, Kadlecek S, Rizi R. Simultaneous quantification of hyperpolarized xenon-129 ventilation and gas exchange with multi-breath xenon-polarization transfer contrast (XTC) MRI. Magn Reson Med 2023; 90:2334-2347. [PMID: 37533368 PMCID: PMC10543483 DOI: 10.1002/mrm.29804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/21/2023] [Accepted: 07/05/2023] [Indexed: 08/04/2023]
Abstract
PURPOSE To demonstrate the feasibility of a multi-breath xenon-polarization transfer contrast (XTC) MR imaging approach for simultaneously evaluating regional ventilation and gas exchange parameters. METHODS Imaging was performed in five healthy volunteers and six chronic obstructive pulmonary disease (COPD) patients. The multi-breath XTC protocol consisted of three repeated schemes of six wash-in breaths of a xenon mixture and four normoxic wash-out breaths, with and without selective saturation of either the tissue membrane or red blood cell (RBC) resonances. Acquisitions were performed at end-exhalation while subjects maintained tidal breathing throughout the session. The no-saturation, membrane-saturation, and RBC-saturation images were fit to a per-breath gas replacement model for extracting voxelwise tidal volume (TV), functional residual capacity (FRC), and fractional ventilation (FV), as well as tissue- and RBC-gas exchange (fMem and fRBC , respectively). The sensitivity of the derived model was also evaluated via simulations. RESULTS With the exception of FRC, whole-lung averages for all metrics were decreased in the COPD subjects compared to the healthy cohort, significantly so for FV, fRBC , and fMem . Heterogeneity was higher overall in the COPD subjects, particularly for fRBC , fMem , and fRBC:Mem . The anterior-to-posterior gradient associated with the gravity-dependence of lung function in supine imaging was also evident for FV, fRBC , and fMem values in the healthy subjects, but noticeably absent in the COPD cohort. CONCLUSION Multi-breath XTC imaging generated high-resolution, co-registered maps of ventilation and gas exchange parameters acquired during tidal breathing and with low per-breath xenon doses. Clear differences between healthy and COPD subjects were apparent and consistent with spirometry.
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Affiliation(s)
- Faraz Amzajerdian
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ryan Baron
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Luis Loza
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ian Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rahim Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Karmali D, Sowho M, Bose S, Pearce J, Tejwani V, Diamant Z, Yarlagadda K, Ponce E, Eikelis N, Otvos T, Khan A, Lester M, Fouras A, Kirkness J, Siddharthan T. Functional imaging for assessing regional lung ventilation in preclinical and clinical research. Front Med (Lausanne) 2023; 10:1160292. [PMID: 37261124 PMCID: PMC10228734 DOI: 10.3389/fmed.2023.1160292] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/17/2023] [Indexed: 06/02/2023] Open
Abstract
Dynamic heterogeneity in lung ventilation is an important measure of pulmonary function and may be characteristic of early pulmonary disease. While standard indices like spirometry, body plethysmography, and blood gases have been utilized to assess lung function, they do not provide adequate information on regional ventilatory distribution nor function assessments of ventilation during the respiratory cycle. Emerging technologies such as xenon CT, volumetric CT, functional MRI and X-ray velocimetry can assess regional ventilation using non-invasive radiographic methods that may complement current methods of assessing lung function. As a supplement to current modalities of pulmonary function assessment, functional lung imaging has the potential to identify respiratory disease phenotypes with distinct natural histories. Moreover, these novel technologies may offer an optimal strategy to evaluate the effectiveness of novel therapies and therapies targeting localized small airways disease in preclinical and clinical research. In this review, we aim to discuss the features of functional lung imaging, as well as its potential application and limitations to adoption in research.
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Affiliation(s)
- Dipan Karmali
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
| | - Mudiaga Sowho
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Sonali Bose
- Division of Pulmonary and Critical Care, Icahn School of Medicine, Mount Sinai, NY, United States
| | - Jackson Pearce
- School of Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Vickram Tejwani
- Respiratory Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Zuzana Diamant
- Department of Microbiology Immunology and Transplantation, KU Leuven, Catholic University of Leuven, Leuven, Belgium
- Department of Respiratory Medicine and Allergology, Institute for Clinical Science, Skane University Hospital, Lund University, Lund, Sweden
- Department Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Keerthi Yarlagadda
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
| | - Erick Ponce
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
| | | | | | - Akram Khan
- Division of Pulmonary and Critical Care, Oregon Health and Science University, Portland, OR, United States
| | - Michael Lester
- Department of Pulmonary and Critical Care Medicine, Vanderbilt Medical Center, Nashville, CA, United States
| | | | | | - Trishul Siddharthan
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
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Hsia CCW, Bates JHT, Driehuys B, Fain SB, Goldin JG, Hoffman EA, Hogg JC, Levin DL, Lynch DA, Ochs M, Parraga G, Prisk GK, Smith BM, Tawhai M, Vidal Melo MF, Woods JC, Hopkins SR. Quantitative Imaging Metrics for the Assessment of Pulmonary Pathophysiology: An Official American Thoracic Society and Fleischner Society Joint Workshop Report. Ann Am Thorac Soc 2023; 20:161-195. [PMID: 36723475 PMCID: PMC9989862 DOI: 10.1513/annalsats.202211-915st] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Multiple thoracic imaging modalities have been developed to link structure to function in the diagnosis and monitoring of lung disease. Volumetric computed tomography (CT) renders three-dimensional maps of lung structures and may be combined with positron emission tomography (PET) to obtain dynamic physiological data. Magnetic resonance imaging (MRI) using ultrashort-echo time (UTE) sequences has improved signal detection from lung parenchyma; contrast agents are used to deduce airway function, ventilation-perfusion-diffusion, and mechanics. Proton MRI can measure regional ventilation-perfusion ratio. Quantitative imaging (QI)-derived endpoints have been developed to identify structure-function phenotypes, including air-blood-tissue volume partition, bronchovascular remodeling, emphysema, fibrosis, and textural patterns indicating architectural alteration. Coregistered landmarks on paired images obtained at different lung volumes are used to infer airway caliber, air trapping, gas and blood transport, compliance, and deformation. This document summarizes fundamental "good practice" stereological principles in QI study design and analysis; evaluates technical capabilities and limitations of common imaging modalities; and assesses major QI endpoints regarding underlying assumptions and limitations, ability to detect and stratify heterogeneous, overlapping pathophysiology, and monitor disease progression and therapeutic response, correlated with and complementary to, functional indices. The goal is to promote unbiased quantification and interpretation of in vivo imaging data, compare metrics obtained using different QI modalities to ensure accurate and reproducible metric derivation, and avoid misrepresentation of inferred physiological processes. The role of imaging-based computational modeling in advancing these goals is emphasized. Fundamental principles outlined herein are critical for all forms of QI irrespective of acquisition modality or disease entity.
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Verbanck SAB, Foy BH. In asthma positive phase III slopes result from structural heterogeneity of the bronchial tree. J Appl Physiol (1985) 2022; 132:947-955. [PMID: 35175103 DOI: 10.1152/japplphysiol.00687.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously identified bronchial generations 5-7 as the locus of maximum contribution to the convective portion of the phase III slope in CT-based lung models of asthma patients. In the present study, we examined how exactly phase III slope is generated locally, by specifically interrogating at individual branch points, the necessary condition for a phase III slope to occur : some degree of convective flow sequencing between any two daughter branches that have a heterogeneity in gas washout concentration between them. Flow sequencing at individual branch points showed a wide range of values, including branch points where flow sequencing was such that phase III slopes were negative locally. Yet, the net effect in the 24 bronchial trees that we studied was that flow sequencing between least and best ventilated units was of the correct sign to generate a positive phase III slope in generations 5-7. By investigating the link of local flow sequencing between any two daughter branches to the corresponding heterogeneity of mechanical lung properties, heterogeneity of compliance was seen to be a major determinant of flow sequencing. In these structures bronchial structures, compliance heterogeneity was essentially brought about by volume asymmetry resulting from terminating pathways within the 3D confines of the lung contours. We conclude that the serial and parallel combination of lung mechanical properties at individual branch points in an asymmetrical branching network generate flow sequencing in mid-range conductive airways, so as to obtain positive at-mouth phase III slopes.
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Affiliation(s)
- Sylvia A B Verbanck
- Respiratory Division, University Hospital (UZ Brussel), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Brody Harry Foy
- Center for Systems Biology and Dept of Pathology, Massachusetts General Hospital, Boston, MA, United States.,Dept of Systems Biology, Harvard Medical School, Boston, MA, United States
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