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Virgincar RS, Nouls JC, Wang Z, Degan S, Qi Y, Xiong X, Rajagopal S, Driehuys B. Quantitative 129Xe MRI detects early impairment of gas-exchange in a rat model of pulmonary hypertension. Sci Rep 2020; 10:7385. [PMID: 32355256 PMCID: PMC7193602 DOI: 10.1038/s41598-020-64361-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2020] [Indexed: 12/19/2022] Open
Abstract
Hyperpolarized 129Xe magnetic resonance imaging (MRI) is capable of regional mapping of pulmonary gas-exchange and has found application in a wide range of pulmonary disorders in humans and animal model analogs. This study is the first application of 129Xe MRI to the monocrotaline rat model of pulmonary hypertension. Such models of preclinical pulmonary hypertension, a disease of the pulmonary vasculature that results in right heart failure and death, are usually assessed with invasive procedures such as right heart catheterization and histopathology. The work here adapted from protocols from clinical 129Xe MRI to enable preclinical imaging of rat models of pulmonary hypertension on a Bruker 7 T scanner. 129Xe spectroscopy and gas-exchange imaging showed reduced 129Xe uptake by red blood cells early in the progression of the disease, and at a later time point was accompanied by increased uptake by barrier tissues, edema, and ventilation defects-all of which are salient characteristics of the monocrotaline model. Imaging results were validated by H&E histology, which showed evidence of remodeling of arterioles. This proof-of-concept study has demonstrated that hyperpolarized 129Xe MRI has strong potential to be used to non-invasively monitor the progression of pulmonary hypertension in preclinical models and potentially to also assess response to therapy.
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Affiliation(s)
- Rohan S Virgincar
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - John C Nouls
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Ziyi Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Simone Degan
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Yi Qi
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Xinyu Xiong
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | | | - Bastiaan Driehuys
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Department of Radiology, Duke University Medical Center, Durham, NC, USA.
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Nouls JC, Virgincar RS, Culbert AG, Morand N, Bobbert DW, Yoder AD, Schopler RS, Bashir MR, Badea A, Hochgeschwender U, Driehuys B. Applications of 3D printing in small animal magnetic resonance imaging. J Med Imaging (Bellingham) 2019; 6:021605. [PMID: 31131288 PMCID: PMC6519666 DOI: 10.1117/1.jmi.6.2.021605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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: 09/14/2018] [Accepted: 04/15/2019] [Indexed: 11/14/2022] Open
Abstract
Three-dimensional (3D) printing has significantly impacted the quality, efficiency, and reproducibility of preclinical magnetic resonance imaging. It has vastly expanded the ability to produce MR-compatible parts that readily permit customization of animal handling, achieve consistent positioning of anatomy and RF coils promptly, and accelerate throughput. It permits the rapid and cost-effective creation of parts customized to a specific imaging study, animal species, animal weight, or even one unique animal, not routinely used in preclinical research. We illustrate the power of this technology by describing five preclinical studies and specific solutions enabled by different 3D printing processes and materials. We describe fixtures, assemblies, and devices that were created to ensure the safety of anesthetized lemurs during an MR examination of their brain or to facilitate localized, contrast-enhanced measurements of white blood cell concentration in a mouse model of pancreatitis. We illustrate expansive use of 3D printing to build a customized birdcage coil and components of a ventilator to enable imaging of pulmonary gas exchange in rats using hyperpolarizedXe 129 . Finally, we present applications of 3D printing to create high-quality, dual RF coils to accelerate brain connectivity mapping in mouse brain specimens and to increase the throughput of brain tumor examinations in a mouse model of pituitary adenoma.
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Affiliation(s)
- John C. Nouls
- Duke University Medical Center, Department of Radiology, Durham, North Carolina, United States
| | - Rohan S. Virgincar
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
| | - Alexander G. Culbert
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
| | | | - Dana W. Bobbert
- Duke University, Office of Information Technology, Durham, North Carolina, United States
| | - Anne D. Yoder
- Duke University, Department of Biology, Durham, North Carolina, United States
- Duke University, Lemur Center, Durham, North Carolina, United States
| | | | - Mustafa R. Bashir
- Duke University Medical Center, Department of Radiology, Durham, North Carolina, United States
| | - Alexandra Badea
- Duke University Medical Center, Department of Radiology, Durham, North Carolina, United States
| | - Ute Hochgeschwender
- Central Michigan University, College of Medicine, Mount Pleasant, Michigan, United States
| | - Bastiaan Driehuys
- Duke University Medical Center, Department of Radiology, Durham, North Carolina, United States
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
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Ebner L, Virgincar RS, He M, Choudhury KR, Robertson SH, Christe A, Mileto A, Mammarapallil JG, McAdams HP, Driehuys B, Roos JE. Multireader Determination of Clinically Significant Obstruction Using Hyperpolarized 129Xe-Ventilation MRI. AJR Am J Roentgenol 2019; 212:758-765. [PMID: 30779661 PMCID: PMC7079551 DOI: 10.2214/ajr.18.20036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of our study was to identify the magnitude and distribution of ventilation defect scores (VDSs) derived from hyperpolarized (HP) 129Xe-MRI associated with clinically relevant airway obstruction. MATERIALS AND METHODS From 2012 to 2015, 76 subjects underwent HP 129Xe-MRI (48 healthy volunteers [mean age ± SD, 54 ± 17 years]; 20 patients with asthma [mean age, 44 ± 20 years]; eight patients with chronic obstructive pulmonary disease [mean age, 67 ± 5 years]). All subjects underwent spirometry 1 day before MRI to establish the presence of airway obstruction (forced expiratory volume in 1 second-to-forced vital capacity ratio [FEV1/FVC] < 70%). Five blinded readers assessed the degree of ventilation impairment and assigned a VDS (range, 0-100%). Interreader agreement was assessed using the Fleiss kappa statistic. Using FEV1/FVC as the reference standard, the optimum VDS threshold for the detection of airway obstruction was estimated using ROC curve analysis with 10-fold cross-validation. RESULTS Compared with the VDSs in healthy subjects, VDSs in patients with airway obstruction were significantly higher (p < 0.0001) and significantly correlated with disease severity (r = 0.66, p < 0.0001). Ventilation defects in subjects with airway obstruction did not show a location-specific pattern (p = 0.158); however, defects in healthy control subjects were more prevalent in the upper lungs (p = 0.014). ROC curve analysis yielded an optimal threshold of 12.4% ± 6.1% (mean ± SD) for clinically significant VDS. Interreader agreement for 129Xe-MRI was substantial (κ = 0.71). CONCLUSION This multireader study of a diverse cohort of patients and control subjects suggests a 129Xe-ventilation MRI VDS of 12.4% or greater represents clinically significant obstruction.
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Affiliation(s)
- Lukas Ebner
- 1 Department of Radiology, Duke University Medical Center, 2301 Erwin Rd, Box 3808, Durham, NC 27710
- 2 Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Rohan S Virgincar
- 3 Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC
| | - Mu He
- 3 Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC
- 4 Department of Radiology, University of Washington School of Medicine, Seattle, WA
| | - Kingshuk R Choudhury
- 1 Department of Radiology, Duke University Medical Center, 2301 Erwin Rd, Box 3808, Durham, NC 27710
| | - Scott H Robertson
- 3 Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC
- 4 Department of Radiology, University of Washington School of Medicine, Seattle, WA
| | - Andreas Christe
- 2 Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Achille Mileto
- 5 Department of Radiology, Cantonal Hospital, Lucerne, Switzerland
| | - Joseph G Mammarapallil
- 1 Department of Radiology, Duke University Medical Center, 2301 Erwin Rd, Box 3808, Durham, NC 27710
| | - H Page McAdams
- 1 Department of Radiology, Duke University Medical Center, 2301 Erwin Rd, Box 3808, Durham, NC 27710
| | - Bastiaan Driehuys
- 1 Department of Radiology, Duke University Medical Center, 2301 Erwin Rd, Box 3808, Durham, NC 27710
- 2 Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- 3 Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC
- 5 Department of Radiology, Cantonal Hospital, Lucerne, Switzerland
| | - Justus E Roos
- 6 Department of Radiology and Nuclear Medicine, Cantonal Hospital, Lucerne, Switzerland
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Virgincar RS, Dahlke J, Robertson SH, Morand N, Qi Y, Degan S, Driehuys B, Nouls JC. A portable ventilator with integrated physiologic monitoring for hyperpolarized 129Xe MRI in rodents. J Magn Reson 2018; 295:63-71. [PMID: 30125865 PMCID: PMC6719309 DOI: 10.1016/j.jmr.2018.07.017] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/13/2018] [Accepted: 07/21/2018] [Indexed: 05/09/2023]
Abstract
Hyperpolarized (HP) 129Xe MRI is emerging as a powerful, non-invasive method to image lung function and is beginning to find clinical application across a range of conditions. As clinical implementation progresses, it becomes important to translate back to well-defined animal models, where novel disease signatures can be characterized longitudinally and validated against histology. To date, preclinical 129Xe MRI has been limited to only a few sites worldwide with 2D imaging that is not generally sufficient to fully capture the heterogeneity of lung disease. To address these limitations and facilitate broader dissemination, we report on a compact and portable HP gas ventilator that integrates all the gas-delivery and physiologic monitoring capabilities required for high-resolution 3D hyperpolarized 129Xe imaging. This ventilator is MR- and HP-gas compatible, driven by inexpensive microcontrollers and open source code, and allows for precise control of the tidal volume and breathing cycle in perorally intubated mice and rats. We use the system to demonstrate data acquisition over multiple breath-holds, during which lung motion is suspended to enable high-resolution 3D imaging of gas-phase and dissolved-phase 129Xe in the lungs. We demonstrate the portability and versatility of the ventilator by imaging a mouse model of lung cancer longitudinally at 2 Tesla, and a healthy rat at 7 Tesla. We also report the detection of subtle spectroscopic fluctuations in phase with the heart rate, superimposed onto larger variations stemming from the respiratory cycle. This ventilator was developed to facilitate duplication and gain broad adoption to accelerate preclinical 129Xe MRI research.
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Affiliation(s)
| | - Jerry Dahlke
- Radiology, Duke University Medical Center, Durham, NC, USA
| | | | | | - Yi Qi
- Radiology, Duke University Medical Center, Durham, NC, USA
| | - Simone Degan
- Radiology, Duke University Medical Center, Durham, NC, USA
| | - Bastiaan Driehuys
- Biomedical Engineering, Duke University, Durham, NC, USA; Radiology, Duke University Medical Center, Durham, NC, USA; Medical Physics Graduate Program, Duke University, Durham, NC, USA
| | - John C Nouls
- Radiology, Duke University Medical Center, Durham, NC, USA.
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5
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Wang JM, Robertson SH, Wang Z, He M, Virgincar RS, Schrank GM, Smigla RM, O'Riordan TG, Sundy J, Ebner L, Rackley CR, McAdams P, Driehuys B. Using hyperpolarized 129Xe MRI to quantify regional gas transfer in idiopathic pulmonary fibrosis. Thorax 2017; 73:21-28. [PMID: 28860333 DOI: 10.1136/thoraxjnl-2017-210070] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [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: 01/27/2017] [Revised: 07/19/2017] [Accepted: 08/02/2017] [Indexed: 11/04/2022]
Abstract
BACKGROUND Assessing functional impairment, therapeutic response and disease progression in patients with idiopathic pulmonary fibrosis (IPF) continues to be challenging. Hyperpolarized 129Xe MRI can address this gap through its unique capability to image gas transfer three-dimensionally from airspaces to interstitial barrier tissues to red blood cells (RBCs). This must be validated by testing the degree to which it correlates with pulmonary function tests (PFTs) and CT scores, and its spatial distribution reflects known physiology and patterns of disease. METHODS 13 healthy individuals (33.6±15.7 years) and 12 patients with IPF (66.0±6.4 years) underwent 129Xe MRI to generate three-dimensional quantitative maps depicting the 129Xe ventilation distribution, its uptake in interstitial barrier tissues and its transfer to RBCs. For each map, mean values were correlated with PFTs and CT fibrosis scores, and their patterns were tested for the ability to depict functional gravitational gradients in healthy lung and to detect the known basal and peripheral predominance of disease in IPF. RESULTS 129Xe MRI depicted functional impairment in patients with IPF, whose mean barrier uptake increased by 188% compared with the healthy reference population. 129Xe MRI metrics correlated poorly and insignificantly with CT fibrosis scores but strongly with PFTs. Barrier uptake and RBC transfer both correlated significantly with diffusing capacity of the lungs for carbon monoxide (r=-0.75, p<0.01 and r=0.72, p<0.01), while their ratio (RBC/barrier) correlated most strongly (r=0.94, p<0.01). RBC transfer exhibited significant anterior-posterior gravitational gradients in healthy volunteers, but not in IPF, where it was significantly impaired in the basal (p=0.02) and subpleural (p<0.01) lung. CONCLUSIONS Hyperpolarized129Xe MRI is a rapid and well-tolerated exam that provides region-specific quantification of interstitial barrier thickness and RBC transfer efficiency. With further development, it could become a robust tool for measuring disease progression and therapeutic response in patients with IPF, sensitively and non-invasively.
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Affiliation(s)
- Jennifer M Wang
- School of Medicine, Duke University, Durham, North Carolina, USA
| | - Scott H Robertson
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Ziyi Wang
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Mu He
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, USA
| | - Rohan S Virgincar
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Geoffry M Schrank
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA
| | - Rose Marie Smigla
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care, Duke University Medical Center, Durham, North Carolina, USA
| | - Thomas G O'Riordan
- Department of Respiratory Medicine, Gilead Sciences Inc, Foster City, California, USA
| | - John Sundy
- Department of Respiratory Medicine, Gilead Sciences Inc, Foster City, California, USA
| | - Lukas Ebner
- Department of Radiology, University Hospital Inselspital, University of Bern, Bern, Switzerland.,Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Craig R Rackley
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care, Duke University Medical Center, Durham, North Carolina, USA
| | - Page McAdams
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.,Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
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6
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Wang Z, Robertson SH, Wang J, He M, Virgincar RS, Schrank GM, Bier EA, Rajagopal S, Huang YC, O'Riordan TG, Rackley CR, McAdams HP, Driehuys B. Quantitative analysis of hyperpolarized129Xe gas transfer MRI. Med Phys 2017; 44:2415-2428. [DOI: 10.1002/mp.12264] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 03/26/2017] [Accepted: 03/30/2017] [Indexed: 12/14/2022] Open
Affiliation(s)
- Ziyi Wang
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
- Department of Biomedical Engineering; Duke University; Durham NC 27708 USA
| | - Scott Haile Robertson
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
- Medical Physics Graduate Program; Duke University; Durham NC 27705 USA
| | - Jennifer Wang
- School of Medicine; Duke University; Durham NC 27710 USA
| | - Mu He
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
- Department of Electrical and Computer Engineering; Duke University; Durham NC 27708 USA
| | - Rohan S. Virgincar
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
- Department of Biomedical Engineering; Duke University; Durham NC 27708 USA
| | - Geoffry M. Schrank
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
| | - Elianna A. Bier
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
- Medical Physics Graduate Program; Duke University; Durham NC 27705 USA
| | | | - Yuh Chin Huang
- Department of Medicine; Division of Pulmonary, Allergy and Critical Care; Duke University Medical Center; Durham NC 27710 USA
| | | | - Craig R. Rackley
- Department of Medicine; Division of Pulmonary, Allergy and Critical Care; Duke University Medical Center; Durham NC 27710 USA
| | - H Page McAdams
- Department of Radiology; Duke University Medical Center; Durham NC 27710 USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy; Duke University Medical Center; Durham NC 27710 USA
- Department of Biomedical Engineering; Duke University; Durham NC 27708 USA
- Medical Physics Graduate Program; Duke University; Durham NC 27705 USA
- Department of Radiology; Duke University Medical Center; Durham NC 27710 USA
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House JS, Nichols CE, Li H, Brandenberger C, Virgincar RS, DeGraff LM, Driehuys B, Zeldin DC, London SJ. Vagal innervation is required for pulmonary function phenotype in Htr4-/- mice. Am J Physiol Lung Cell Mol Physiol 2017; 312:L520-L530. [PMID: 28130264 PMCID: PMC5407097 DOI: 10.1152/ajplung.00495.2016] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/19/2017] [Accepted: 01/25/2017] [Indexed: 11/22/2022] Open
Abstract
Human genome-wide association studies have identified over 50 loci associated with pulmonary function and related phenotypes, yet follow-up studies to determine causal genes or variants are rare. Single nucleotide polymorphisms in serotonin receptor 4 (HTR4) are associated with human pulmonary function in genome-wide association studies and follow-up animal work has demonstrated that Htr4 is causally associated with pulmonary function in mice, although the precise mechanisms were not identified. We sought to elucidate the role of neural innervation and pulmonary architecture in the lung phenotype of Htr4-/- animals. We report here that the Htr4-/- phenotype in mouse is dependent on vagal innervation to the lung. Both ex vivo tracheal ring reactivity and in vivo flexiVent pulmonary functional analyses demonstrate that vagotomy abrogates the Htr4-/- airway hyperresponsiveness phenotype. Hyperpolarized 3He gas magnetic resonance imaging and stereological assessment of wild-type and Htr4-/- mice reveal no observable differences in lung volume, inflation characteristics, or pulmonary microarchitecture. Finally, control of breathing experiments reveal substantive differences in baseline breathing characteristics between mice with/without functional HTR4 in breathing frequency, relaxation time, flow rate, minute volume, time of inspiration and expiration and breathing pauses. These results suggest that HTR4's role in pulmonary function likely relates to neural innervation and control of breathing.
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Affiliation(s)
- John S House
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Cody E Nichols
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Huiling Li
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | | | - Rohan S Virgincar
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina.,Biomedical Engineering, Duke University, Durham, North Carolina
| | - Laura M DeGraff
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina.,Biomedical Engineering, Duke University, Durham, North Carolina.,Radiology, Duke University Medical Center, Durham, North Carolina; and
| | - Darryl C Zeldin
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Stephanie J London
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina; .,Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
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Robertson SH, Virgincar RS, Bier EA, He M, Schrank GM, Smigla RM, Rackley C, McAdams HP, Driehuys B. Uncovering a third dissolved-phase 129 Xe resonance in the human lung: Quantifying spectroscopic features in healthy subjects and patients with idiopathic pulmonary fibrosis. Magn Reson Med 2016; 78:1306-1315. [PMID: 28940334 DOI: 10.1002/mrm.26533] [Citation(s) in RCA: 17] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 09/12/2016] [Accepted: 10/06/2016] [Indexed: 01/25/2023]
Abstract
PURPOSE The purpose of this work was to accurately characterize the spectral properties of hyperpolarized 129 Xe in patients with idiopathic pulmonary fibrosis (IPF) compared to healthy volunteers. METHODS Subjects underwent hyperpolarized 129 Xe breath-hold spectroscopy, during which 38 dissolved-phase free induction decays (FIDs) were acquired after reaching steady state (echo time/repetition time = 0.875/50 ms; bandwidth = 8.06 kHz; flip angle≈22 °). FIDs were averaged and then decomposed into multiple spectral components using time-domain curve fitting. The resulting amplitudes, frequencies, line widths, and starting phases of each component were compared among groups using a Mann-Whitney-Wilcoxon U test. RESULTS Three dissolved-phase resonances, consisting of red blood cells (RBCs) and two barrier compartments, were consistently identified in all subjects. In subjects with IPF relative to healthy volunteers, the RBC frequency was 0.70 parts per million (ppm) more negative (P = 0.05), the chemical shift of barrier 2 was 0.6 ppm more negative (P = 0.009), the line widths of both barrier peaks were ∼2 ppm narrower (P < 0.001), and the starting phase of barrier 1 was 20.3 ° higher (P = 0.01). Moreover, the ratio RBC:barriers was reduced by 52.9% in IPF (P < 0.001). CONCLUSIONS The accurate decomposition of 129 Xe spectra not only has merit for developing a global metric of pulmonary function, but also provides necessary insights to optimize phase-sensitive methods for imaging 129 Xe gas transfer. Magn Reson Med 78:1306-1315, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Scott H Robertson
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Rohan S Virgincar
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Elianna A Bier
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - Mu He
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, USA
| | - Geoffrey M Schrank
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA
| | - Rose Marie Smigla
- Division of Pulmonary, Allergy and Critical Care, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Craig Rackley
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - H Page McAdams
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.,Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
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9
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Virgincar RS, Robertson SH, Nouls J, Degan S, Schrank GM, He M, Driehuys B. Establishing an accurate gas phase reference frequency to quantify 129 Xe chemical shifts in vivo. Magn Reson Med 2016; 77:1438-1445. [PMID: 27059646 DOI: 10.1002/mrm.26229] [Citation(s) in RCA: 8] [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: 11/25/2015] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 12/25/2022]
Abstract
PURPOSE 129 Xe interacts with biological media to exhibit chemical shifts exceeding 200 ppm that report on physiology and pathology. Extracting this functional information requires shifts to be measured precisely. Historically, shifts have been reported relative to the gas-phase resonance originating from pulmonary airspaces. However, this frequency is not fixed-it is affected by bulk magnetic susceptibility, as well as Xe-N2 , Xe-Xe, and Xe-O2 interactions. In this study, we addressed this by introducing a robust method to determine the 0 ppm 129 Xe reference from in vivo data. METHODS Respiratory-gated hyperpolarized 129 Xe spectra from the gas- and dissolved-phases were acquired in four mice at 2T from multiple axial slices within the thoracic cavity. Complex spectra were then fitted in the time domain to identify peaks. RESULTS Gas-phase 129 Xe exhibited two distinct resonances corresponding to 129 Xe in conducting airways (varying from -0.6 ± 0.2 to 1.3 ± 0.3 ppm) and alveoli (relatively stable, at -2.2 ± 0.1 ppm). Dissolved-phase 129 Xe exhibited five reproducible resonances in the thorax at 198.4 ± 0.4, 195.5 ± 0.4, 193.9 ± 0.2, 191.3 ± 0.2, and 190.7 ± 0.3 ppm. CONCLUSION The alveolar 129 Xe resonance exhibits a stable frequency across all mice. Therefore, it can provide a reliable in vivo reference frequency by which to characterize other spectroscopic shifts. Magn Reson Med 77:1438-1445, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Rohan S Virgincar
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Scott H Robertson
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
| | - John Nouls
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Simone Degan
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Center for Molecular and Biomolecular Imaging, Duke University Medical Center, Durham, North Carolina, USA
| | - Geoffry M Schrank
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Mu He
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Electrical and Computer Engineering, Duke University, Durham North Carolina, USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, USA.,Biomedical Engineering, Duke University, Durham, North Carolina, USA.,Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA.,Radiology, Duke University Medical Center, Durham, North Carolina, USA
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He M, Robertson SH, Kaushik SS, Freeman MS, Virgincar RS, Davies J, Stiles J, Foster WM, McAdams HP, Driehuys B. Dose and pulse sequence considerations for hyperpolarized (129)Xe ventilation MRI. Magn Reson Imaging 2015; 33:877-85. [PMID: 25936684 DOI: 10.1016/j.mri.2015.04.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [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: 02/19/2015] [Revised: 04/15/2015] [Accepted: 04/19/2015] [Indexed: 01/25/2023]
Abstract
PURPOSE The aim of this study was to evaluate the effect of hyperpolarized (129)Xe dose on image signal-to-noise ratio (SNR) and ventilation defect conspicuity on both multi-slice gradient echo and isotropic 3D-radially acquired ventilation MRI. MATERIALS AND METHODS Ten non-smoking older subjects (ages 60.8±7.9years) underwent hyperpolarized (HP) (129)Xe ventilation MRI using both GRE and 3D-radial acquisitions, each tested using a 71ml (high) and 24ml (low) dose equivalent (DE) of fully polarized, fully enriched (129)Xe. For all images SNR and ventilation defect percentage (VDP) were calculated. RESULTS Normalized SNR (SNRn), obtained by dividing SNR by voxel volume and dose was higher for high-DE GRE acquisitions (SNRn=1.9±0.8ml(-2)) than low-DE GRE scans (SNRn=0.8±0.2ml(-2)). Radially acquired images exhibited a more consistent, albeit lower SNRn (High-DE: SNRn=0.5±0.1ml(-2), low-DE: SNRn=0.5±0.2ml(-2)). VDP was indistinguishable across all scans. CONCLUSIONS These results suggest that images acquired using the high-DE GRE sequence provided the highest SNRn, which was in agreement with previous reports in the literature. 3D-radial images had lower SNRn, but have advantages for visual display, monitoring magnetization dynamics, and visualizing physiological gradients. By evaluating normalized SNR in the context of dose-equivalent formalism, it should be possible to predict (129)Xe dose requirements and quantify the benefits of more efficient transmit/receive coils, field strengths, and pulse sequences.
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Affiliation(s)
- Mu He
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA
| | - Scott H Robertson
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA; Medical Physics Graduate Program, Duke University, Durham, NC, USA
| | - S Sivaram Kaushik
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA; Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Matthew S Freeman
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA; Medical Physics Graduate Program, Duke University, Durham, NC, USA
| | - Rohan S Virgincar
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA; Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - John Davies
- Department of Medicine Pulmonary, Duke University Medical Center, Durham, NC, USA
| | - Jane Stiles
- Department of Medicine Pulmonary, Duke University Medical Center, Durham, NC, USA
| | - William M Foster
- Department of Medicine Pulmonary, Duke University Medical Center, Durham, NC, USA
| | - H Page McAdams
- Medical Physics Graduate Program, Duke University, Durham, NC, USA; Department of Medicine Pulmonary, Duke University Medical Center, Durham, NC, USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA; Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Radiology, Duke University Medical Center, Durham, NC, USA; Medical Physics Graduate Program, Duke University, Durham, NC, USA.
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He M, Kaushik SS, Robertson SH, Freeman MS, Virgincar RS, McAdams HP, Driehuys B. Extending semiautomatic ventilation defect analysis for hyperpolarized (129)Xe ventilation MRI. Acad Radiol 2014; 21:1530-41. [PMID: 25262951 DOI: 10.1016/j.acra.2014.07.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/22/2014] [Accepted: 07/23/2014] [Indexed: 12/25/2022]
Abstract
RATIONALE AND OBJECTIVES Clinical deployment of hyperpolarized (129)Xe magnetic resonance imaging requires accurate quantification and visualization of the ventilation defect percentage (VDP). Here, we improve the robustness of our previous semiautomated analysis method to reduce operator dependence, correct for B1 inhomogeneity and vascular structures, and extend the analysis to display multiple intensity clusters. MATERIALS AND METHODS Two segmentation methods were compared-a seeded region-growing method, previously validated by expert reader scoring, and a new linear-binning method that corrects the effects of bias field and vascular structures. The new method removes nearly all operator interventions by rescaling the (129)Xe magnetic resonance images to the 99th percentile of the cumulative distribution and applying fixed thresholds to classify (129)Xe voxels into four clusters: defect, low, medium, and high intensity. The methods were applied to 24 subjects including patients with chronic obstructive pulmonary disease (n = 8), age-matched controls (n = 8), and healthy normal subjects (n = 8). RESULTS Linear-binning enabled a faster and more reproducible workflow and permitted analysis of an additional 0.25 ± 0.18 L of lung volume by accounting for vasculature. Like region-growing, linear-binning VDP correlated strongly with reader scoring (R(2) = 0.93, P < .0001), but with less systematic bias. Moreover, linear-binning maps clearly depict regions of low and high intensity that may prove useful for phenotyping subjects with chronic obstructive pulmonary disease. CONCLUSIONS Corrected linear-binning provides a robust means to quantify (129)Xe ventilation images yielding VDP values that are indistinguishable from expert reader scores, while exploiting the entire dynamic range to depict multiple image clusters.
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Kaushik SS, Freeman MS, Cleveland ZI, Davies J, Stiles J, Virgincar RS, Robertson SH, He M, Kelly KT, Foster WM, McAdams HP, Driehuys B. Probing the regional distribution of pulmonary gas exchange through single-breath gas- and dissolved-phase 129Xe MR imaging. J Appl Physiol (1985) 2013; 115:850-60. [PMID: 23845983 DOI: 10.1152/japplphysiol.00092.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [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: 11/22/2022] Open
Abstract
Although some central aspects of pulmonary function (ventilation and perfusion) are known to be heterogeneous, the distribution of diffusive gas exchange remains poorly characterized. A solution is offered by hyperpolarized 129Xe magnetic resonance (MR) imaging, because this gas can be separately detected in the lung's air spaces and dissolved in its tissues. Early dissolved-phase 129Xe images exhibited intensity gradients that favored the dependent lung. To quantitatively corroborate this finding, we developed an interleaved, three-dimensional radial sequence to image the gaseous and dissolved 129Xe distributions in the same breath. These images were normalized and divided to calculate "129Xe gas-transfer" maps. We hypothesized that, for healthy volunteers, 129Xe gas-transfer maps would retain the previously observed posture-dependent gradients. This was tested in nine subjects: when the subjects were supine, 129Xe gas transfer exhibited a posterior-anterior gradient of -2.00 ± 0.74%/cm; when the subjects were prone, the gradient reversed to 1.94 ± 1.14%/cm (P < 0.001). The 129Xe gas-transfer maps also exhibited significant heterogeneity, as measured by the coefficient of variation, that correlated with subject total lung capacity (r = 0.77, P = 0.015). Gas-transfer intensity varied nonmonotonically with slice position and increased in slices proximal to the main pulmonary arteries. Despite substantial heterogeneity, the mean gas transfer for all subjects was 1.00 ± 0.01 while supine and 1.01 ± 0.01 while prone (P = 0.25), indicating good "matching" between gas- and dissolved-phase distributions. This study demonstrates that single-breath gas- and dissolved-phase 129Xe MR imaging yields 129Xe gas-transfer maps that are sensitive to altered gas exchange caused by differences in lung inflation and posture.
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Affiliation(s)
- S Sivaram Kaushik
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
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Virgincar RS, Cleveland ZI, Kaushik SS, Freeman MS, Nouls J, Cofer GP, Martinez-Jimenez S, He M, Kraft M, Wolber J, McAdams HP, Driehuys B. Quantitative analysis of hyperpolarized 129Xe ventilation imaging in healthy volunteers and subjects with chronic obstructive pulmonary disease. NMR Biomed 2013; 26:424-35. [PMID: 23065808 PMCID: PMC3624045 DOI: 10.1002/nbm.2880] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [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: 03/12/2012] [Revised: 09/11/2012] [Accepted: 09/12/2012] [Indexed: 05/12/2023]
Abstract
In this study, hyperpolarized (129) Xe MR ventilation and (1) H anatomical images were obtained from three subject groups: young healthy volunteers (HVs), subjects with chronic obstructive pulmonary disease (COPD) and age-matched controls (AMCs). Ventilation images were quantified by two methods: an expert reader-based ventilation defect score percentage (VDS%) and a semi-automated segmentation-based ventilation defect percentage (VDP). Reader-based values were assigned by two experienced radiologists and resolved by consensus. In the semi-automated analysis, (1) H anatomical images and (129) Xe ventilation images were both segmented following registration to obtain the thoracic cavity volume and ventilated volume, respectively, which were then expressed as a ratio to obtain the VDP. Ventilation images were also characterized by generating signal intensity histograms from voxels within the thoracic cavity volume, and heterogeneity was analyzed using the coefficient of variation (CV). The reader-based VDS% correlated strongly with the semi-automatically generated VDP (r = 0.97, p < 0.0001) and with CV (r = 0.82, p < 0.0001). Both (129) Xe ventilation defect scoring metrics readily separated the three groups from one another and correlated significantly with the forced expiratory volume in 1 s (FEV1 ) (VDS%: r = -0.78, p = 0.0002; VDP: r = -0.79, p = 0.0003; CV: r = -0.66, p = 0.0059) and other pulmonary function tests. In the healthy subject groups (HVs and AMCs), the prevalence of ventilation defects also increased with age (VDS%: r = 0.61, p = 0.0002; VDP: r = 0.63, p = 0.0002). Moreover, ventilation histograms and their associated CVs distinguished between subjects with COPD with similar ventilation defect scores, but visibly different ventilation patterns.
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Affiliation(s)
- Rohan S. Virgincar
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Zackary I. Cleveland
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - S. Sivaram Kaushik
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Matthew S. Freeman
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Medical Physics Graduate Program, Duke University, Durham, NC, USA
| | - John Nouls
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Gary P. Cofer
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | | | - Mu He
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA
| | - Monica Kraft
- Department of Pulmonary and Critical Care Medicine, Duke University Medical Center, Durham, NC, USA
| | - Jan Wolber
- GE Healthcare, The Grove Center, White Lion Rd, Amersham, UK
- Academic Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, UK
| | - H. Page McAdams
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Bastiaan Driehuys
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
- Medical Physics Graduate Program, Duke University, Durham, NC, USA
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