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Malmberg MA, Odéen H, Hofstetter LW, Hadley JR, Parker DL. Validation of single reference variable flip angle (SR-VFA) dynamic T 1 mapping with T 2 * correction using a novel rotating phantom. Magn Reson Med 2024; 91:1419-1433. [PMID: 38115639 PMCID: PMC10872756 DOI: 10.1002/mrm.29944] [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: 06/27/2023] [Revised: 10/12/2023] [Accepted: 11/09/2023] [Indexed: 12/21/2023]
Abstract
PURPOSE To validate single reference variable flip angle (SR-VFA) dynamic T1 mapping with and without T2 * correction against inversion recovery (IR) T1 measurements. METHODS A custom cylindrical phantom with three concentric compartments was filled with variably doped agar to produce a smooth spatial gradient of the T1 relaxation rate as a function of angle across each compartment. IR T1 , VFA T1 , and B1 + measurements were made on the phantom before rotation, and multi-echo stack-of-radial dynamic images were acquired during rotation via an MRI-compatible motor. B1 + -corrected SR-VFA and SR-VFA-T2 * T1 maps were computed from the sliding window reconstructed images and compared against rotationally registered IR and VFA T1 maps to determine the percentage error. RESULTS Both VFA and SR-VFA-T2 * T1 maps fell within 10% of IR T1 measurements for a low rotational speed, with a mean accuracy of 2.3% ± 2.6% and 2.8% ± 2.6%, respectively. Increasing rotational speed was found to decrease the accuracy due to increasing temporal smoothing over ranges where the T1 change had a nonconstant slope. SR-VFA T1 mapping was found to have similar accuracy as the SR-VFA-T2 * and VFA methods at low TEs (˜<2 ms), whereas accuracy degraded strongly with later TEs. T2 * correction of the SR-VFA T1 maps was found to consistently improve accuracy and precision, especially at later TEs. CONCLUSION SR-VFA-T2 * dynamic T1 mapping was found to be accurate against reference IR T1 measurements within 10% in an agar phantom. Further validation is needed in mixed fat-water phantoms and in vivo.
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Affiliation(s)
- Michael A. Malmberg
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Henrik Odéen
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | | | - J. Rock Hadley
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Dennis L. Parker
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
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2
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Needleman SH, Kim M, McClelland JR, Naish JH, Tibiletti M, O'Connor JPB, Parker GJM. Independent component analysis (ICA) applied to dynamic oxygen-enhanced MRI (OE-MRI) for robust functional lung imaging at 3 T. Magn Reson Med 2024; 91:955-971. [PMID: 37984456 PMCID: PMC10952250 DOI: 10.1002/mrm.29912] [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: 05/30/2023] [Revised: 09/03/2023] [Accepted: 10/13/2023] [Indexed: 11/22/2023]
Abstract
PURPOSE Dynamic lung oxygen-enhanced MRI (OE-MRI) is challenging due to the presence of confounding signals and poor signal-to-noise ratio, particularly at 3 T. We have created a robust pipeline utilizing independent component analysis (ICA) to automatically extract the oxygen-induced signal change from confounding factors to improve the accuracy and sensitivity of lung OE-MRI. METHODS Dynamic OE-MRI was performed on healthy participants using a dual-echo multi-slice spoiled gradient echo sequence at 3 T and cyclical gas delivery. ICA was applied to each echo within a thoracic mask. The ICA component relating to the oxygen-enhancement signal was automatically identified using correlation analysis. The oxygen-enhancement component was reconstructed, and the percentage signal enhancement (PSE) was calculated. The lung PSE of current smokers was compared with nonsmokers; scan-rescan repeatability, ICA pipeline repeatability, and reproducibility between two vendors were assessed. RESULTS ICA successfully extracted a consistent oxygen-enhancement component for all participants. Lung tissue and oxygenated blood displayed the opposite oxygen-induced signal enhancements. A significant difference in PSE was observed between the lungs of current smokers and nonsmokers. The scan-rescan repeatability and the ICA pipeline repeatability were good. CONCLUSION The developed pipeline demonstrated sensitivity to the signal enhancements of the lung tissue and oxygenated blood at 3 T. The difference in lung PSE between current smokers and nonsmokers indicates a likely sensitivity to lung function alterations that may be seen in mild pathology, supporting future use of our methods in patient studies.
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Affiliation(s)
- Sarah H. Needleman
- Centre for Medical Image Computing (CMIC), Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Mina Kim
- Centre for Medical Image Computing (CMIC), Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Jamie R. McClelland
- Centre for Medical Image Computing (CMIC), Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Josephine H. Naish
- Bioxydyn LimitedManchesterUK
- BHF Manchester Centre for Heart and Lung Magnetic Resonance Research (MCMR), Manchester University NHS Foundation TrustManchesterUK
| | | | | | - Geoff J. M. Parker
- Centre for Medical Image Computing (CMIC), Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- Bioxydyn LimitedManchesterUK
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3
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Bhattacharya I, Ramasawmy R, Javed A, Lowery M, Henry J, Mancini C, Machado T, Jones A, Julien-Williams P, Lederman RJ, Balaban RS, Chen MY, Moss J, Campbell-Washburn AE. Assessment of Lung Structure and Regional Function Using 0.55 T MRI in Patients With Lymphangioleiomyomatosis. Invest Radiol 2022; 57:178-186. [PMID: 34652290 PMCID: PMC9926400 DOI: 10.1097/rli.0000000000000832] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Contemporary lower-field magnetic resonance imaging (MRI) may offer advantages for lung imaging by virtue of the improved field homogeneity. The aim of this study was to evaluate the utility of lower-field MRI for combined morphologic imaging and regional lung function assessment. We evaluate low-field MRI in patients with lymphangioleiomyomatosis (LAM), a rare lung disease associated with parenchymal cysts and respiratory failure. MATERIALS AND METHODS We performed lung imaging on a prototype low-field (0.55 T) MRI system in 65 patients with LAM. T2-weighted imaging was used for assessment of lung morphology and to derive cyst scores, the percent of lung parenchyma occupied by cysts. Regional lung function was assessed using oxygen-enhanced MRI with breath-held ultrashort echo time imaging and inhaled 100% oxygen as a T1-shortening MR contrast agent. Measurements of percent signal enhancement from oxygen inhalation and percentage of lung with low oxygen enhancement, indicating functional deficits, were correlated with global pulmonary function test measurements taken within 2 days. RESULTS We were able to image cystic abnormalities using T2-weighted MRI in this patient population and calculate cyst score with strong correlation to computed tomography measurements (R = 0.86, P < 0.0001). Oxygen-enhancement maps demonstrated regional deficits in lung function of patients with LAM. Heterogeneity of oxygen enhancement between cysts was observed within individual patients. The percent low-enhancement regions showed modest, but significant, correlation with FEV1 (R = -0.37, P = 0.007), FEV1/FVC (R = -0.33, P = 0.02), and cyst score (R = 0.40, P = 0.02). The measured arterial blood ΔT1 between normoxia and hyperoxia, used as a surrogate for dissolved oxygen in blood, correlated with DLCO (R = -0.28, P = 0.03). CONCLUSIONS Using high-performance 0.55 T MRI, we were able to perform simultaneous imaging of pulmonary structure and regional function in patients with LAM.
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Affiliation(s)
- Ipshita Bhattacharya
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Rajiv Ramasawmy
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Ahsan Javed
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Margaret Lowery
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Jennifer Henry
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Christine Mancini
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Tania Machado
- Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Amanda Jones
- Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Patricia Julien-Williams
- Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Robert J Lederman
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Robert S Balaban
- Systems Biology Center, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Marcus Y Chen
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Joel Moss
- Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD, USA 20892
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4
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Hopkins SR. Ventilation/Perfusion Relationships and Gas Exchange: Measurement Approaches. Compr Physiol 2020; 10:1155-1205. [PMID: 32941684 DOI: 10.1002/cphy.c180042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Ventilation-perfusion ( V ˙ A / Q ˙ ) matching, the regional matching of the flow of fresh gas to flow of deoxygenated capillary blood, is the most important mechanism affecting the efficiency of pulmonary gas exchange. This article discusses the measurement of V ˙ A / Q ˙ matching with three broad classes of techniques: (i) those based in gas exchange, such as the multiple inert gas elimination technique (MIGET); (ii) those derived from imaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT), and electrical impedance tomography (EIT); and (iii) fluorescent and radiolabeled microspheres. The focus is on the physiological basis of these techniques that provide quantitative information for research purposes rather than qualitative measurements that are used clinically. The fundamental equations of pulmonary gas exchange are first reviewed to lay the foundation for the gas exchange techniques and some of the imaging applications. The physiological considerations for each of the techniques along with advantages and disadvantages are briefly discussed. © 2020 American Physiological Society. Compr Physiol 10:1155-1205, 2020.
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Affiliation(s)
- Susan R Hopkins
- Departments of Medicine and Radiology, University of California, San Diego, California, USA
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5
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Voskrebenzev A, Vogel-Claussen J. Proton MRI of the Lung: How to Tame Scarce Protons and Fast Signal Decay. J Magn Reson Imaging 2020; 53:1344-1357. [PMID: 32166832 DOI: 10.1002/jmri.27122] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/20/2020] [Accepted: 02/20/2020] [Indexed: 12/19/2022] Open
Abstract
Pulmonary proton MRI techniques offer the unique possibility of assessing lung function and structure without the requirement for hyperpolarization or dedicated hardware, which is mandatory for multinuclear acquisition. Five popular approaches are presented and discussed in this review: 1) oxygen enhanced (OE)-MRI; 2) arterial spin labeling (ASL); 3) Fourier decomposition (FD) MRI and other related methods including self-gated noncontrast-enhanced functional lung (SENCEFUL) MR and phase-resolved functional lung (PREFUL) imaging; 4) dynamic contrast-enhanced (DCE) MRI; and 5) ultrashort TE (UTE) MRI. While DCE MRI is the most established and well-studied perfusion measurement, FD MRI offers a free-breathing test without any contrast agent and is predestined for application in patients with renal failure or with low compliance. Additionally, FD MRI and related methods like PREFUL and SENCEFUL can act as an ionizing radiation-free V/Q scan, since ventilation and perfusion information is acquired simultaneously during one scan. For OE-MRI, different concentrations of oxygen are applied via a facemask to assess the regional change in T1 , which is caused by the paramagnetic property of oxygen. Since this change is governed by a combination of ventilation, diffusion, and perfusion, a compound functional measurement can be achieved with OE-MRI. The known problem of fast T2 * decay of the lung parenchyma leading to a low signal-to-noise ratio is bypassed by the UTE acquisition strategy. Computed tomography (CT)-like images allow the assessment of lung structure with high spatial resolution without ionizing radiation. Despite these different branches of proton MRI, common trends are evident among pulmonary proton MRI: 1) free-breathing acquisition with self-gating; 2) application of UTE to preserve a stronger parenchymal signal; and 3) transition from 2D to 3D acquisition. On that note, there is a visible convergence of the different methods and it is not difficult to imagine that future methods will combine different aspects of the presented methods.
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Affiliation(s)
- Andreas Voskrebenzev
- Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease (BREATH), Member of the German Lung Research Center (DZL), Hannover, Germany
| | - Jens Vogel-Claussen
- Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease (BREATH), Member of the German Lung Research Center (DZL), Hannover, Germany
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6
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Goldfarb JW, Hsu B, Cao JJ. Effects of supplemental oxygen on cardiovascular magnetic resonance water proton relaxation time constant measurements (T 1, T 2 and T 2*). Magn Reson Imaging 2019; 61:124-130. [PMID: 31082495 DOI: 10.1016/j.mri.2019.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/08/2019] [Accepted: 05/04/2019] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To study, the effects of supplemental oxygen on the measurement of native cardiovascular water proton relaxation time constants using commercially available protocols. METHODS T1, T2 and T2* relaxation time constant mapping were performed in twelve volunteers at 1.5 T breathing room air and supplemental oxygen supplied by nasal cannula and a non-rebreather mask. Regions-of-interest were drawn for quantitative measurements in the bloodpool of each ventricle and atria as well as septal myocardium. The effects of supplemental oxygen were investigated statistically using a mixed model analysis of variance. Intra- and inter-observer reproducibility were assessed using the Intraclass Correlation Coefficient and Coefficient of Variation. RESULTS Blood T1 relaxation time constants in the left ventricle (T1 change = -241.0 ms) and left atrium (T1 change = -247.0 ms) decreased significantly in every subject after oxygen inhalation with a non-rebreather mask (p < 0.001). No significant changes of T1 in the right side of the heart were detected after oxygen inhalation with the non-rebreather mask (p = 0.345). Oxygen inhalation with nasal cannula did not significantly change blood T1 in the study (p = 0.497). No significant changes in myocardial T1 (p = 0.390), T2 (p = 0.960) or T2* (p = 0.438) were observed with supplemental oxygen supplied by nasal cannula or the non-rebreather mask. Results were similar in mid-short-axis and horizontal long-axis acquisitions. CONCLUSION Supplemental oxygen does not affect myocardial relaxation time constant measurements with current protocols. On the other hand, blood T1 measurements with the inhalation of supplemental oxygen supplied by a non-rebreather mask change significantly and could affect myocardial tissue characterization if used for the calculation of extracellular volume. Additionally, current relaxation time constant mapping protocols do not reproducibly detect myocardial T1 changes with supplemental oxygen inhalation.
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Affiliation(s)
- James W Goldfarb
- Department of Research and Education, Saint Francis Hospital Roslyn, NY, USA.
| | - Brittany Hsu
- Department of Research and Education, Saint Francis Hospital Roslyn, NY, USA.
| | - Jie J Cao
- Department of Research and Education, Saint Francis Hospital Roslyn, NY, USA.
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7
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Semple T, Akhtar MR, Owens CM. Imaging Bronchopulmonary Dysplasia-A Multimodality Update. Front Med (Lausanne) 2017; 4:88. [PMID: 28725645 PMCID: PMC5497953 DOI: 10.3389/fmed.2017.00088] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 06/07/2017] [Indexed: 01/13/2023] Open
Abstract
Bronchopulmonary dysplasia is the most common form of infantile chronic lung
disease and results in significant health-care expenditure. The roles of chest
radiography and computed tomography (CT) are well documented but numerous recent
advances in imaging technology have paved the way for newer imaging techniques
including structural pulmonary assessment via lung magnetic
resonance imaging (MRI), functional assessment via ventilation,
and perfusion MRI and quantitative imaging techniques using both CT and MRI. New
applications for ultrasound have also been suggested. With the increasing array
of complex technologies available, it is becoming increasingly important to have
a deeper knowledge of the technological advances of the past
5–10 years and particularly the limitations of some newer
techniques currently undergoing intense research. This review article aims to
cover the most salient advances relevant to BPD imaging, particularly advances
within CT technology, postprocessing and quantitative CT; structural MRI
assessment, ventilation and perfusion imaging using gas contrast agents and
Fourier decomposition techniques and lung ultrasound.
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Affiliation(s)
- Thomas Semple
- The Royal Brompton Hospital, London, United Kingdon.,Great Ormond Street Hospital, London, United Kingdom
| | - Mohammed R Akhtar
- St Bartholomews and The Royal London Hospital, London, United Kingdom
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8
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Bauman G, Pusterla O, Santini F, Bieri O. Dynamic and steady-state oxygen-dependent lung relaxometry using inversion recovery ultra-fast steady-state free precession imaging at 1.5 T. Magn Reson Med 2017; 79:839-845. [PMID: 28520198 DOI: 10.1002/mrm.26739] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/06/2017] [Accepted: 04/06/2017] [Indexed: 12/31/2022]
Abstract
PURPOSE To demonstrate the feasibility of oxygen-dependent relaxometry in human lung using an inversion recovery ultra-fast steady-state free precession (IR-ufSSFP) technique. METHODS Electrocardiogram-triggered pulmonary relaxometry with IR-ufSSFP was performed in 7 healthy human subjects at 1.5 T. The data were acquired under both normoxic and hyperoxic conditions. In a single breath-hold of less than 9 seconds, 30 transient state IR-ufSSFP images were acquired, yielding longitudinal (T1) and transversal (T2) relaxometry parameter maps using voxel-wise nonlinear fitting. Possible spatial misalignments between consecutive IR-ufSSFP parameter maps were corrected using elastic image registration. Furthermore, dynamic relaxometry oxygen wash-in and wash-out scans were performed in one volunteer. From this, T1 -related wash-in and wash-out time constants (τwi , τwo ) were calculated voxel-wise on registered maps using an exponential fitting model. RESULTS For healthy lung, observed T1 values were 1399 ± 77 and 1290 ± 76 ms under normoxic and hyperoxic conditions, respectively. Oxygen-related reduction of T1 was statistically significant in every volunteer. No statistically significant change, however, was observed in T2, with normoxic and hyperoxic T2 values of 55 ± 16 and 56 ± 17 ms, respectively. The observed average τwi was 87.0 ± 28.7 seconds, whereas the average τwo was 73.5 ± 21.6 seconds. CONCLUSION IR-ufSSFP allows fast, steady-state, and dynamic oxygen-dependent relaxometry of the human lung. Magn Reson Med 79:839-845, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Grzegorz Bauman
- Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.,Deparment of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Orso Pusterla
- Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.,Deparment of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Francesco Santini
- Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.,Deparment of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Oliver Bieri
- Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.,Deparment of Biomedical Engineering, University of Basel, Basel, Switzerland
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9
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Kindvall SSI, Diaz S, Svensson J, Wollmer P, Olsson LE. The change of longitudinal relaxation rate in oxygen enhanced pulmonary MRI depends on age and BMI but not diffusing capacity of carbon monoxide in healthy never-smokers. PLoS One 2017; 12:e0177670. [PMID: 28494006 PMCID: PMC5426684 DOI: 10.1371/journal.pone.0177670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 05/01/2017] [Indexed: 12/02/2022] Open
Abstract
OBJECTIVE Oxygen enhanced pulmonary MRI is a promising modality for functional lung studies and has been applied to a wide range of pulmonary conditions. The purpose of this study was to characterize the oxygen enhancement effect in the lungs of healthy, never-smokers, in light of a previously established relationship between oxygen enhancement and diffusing capacity of carbon monoxide in the lung (DL,CO) in patients with lung disease. METHODS In 30 healthy never-smoking volunteers, an inversion recovery with gradient echo read-out (Snapshot-FLASH) was used to quantify the difference in longitudinal relaxation rate, while breathing air and 100% oxygen, ΔR1, at 1.5 Tesla. Measurements were performed under multiple tidal inspiration breath-holds. RESULTS In single parameter linear models, ΔR1 exhibit a significant correlation with age (p = 0.003) and BMI (p = 0.0004), but not DL,CO (p = 0.33). Stepwise linear regression of ΔR1 yields an optimized model including an age-BMI interaction term. CONCLUSION In this healthy, never-smoking cohort, age and BMI are both predictors of the change in MRI longitudinal relaxation rate when breathing oxygen. However, DL,CO does not show a significant correlation with the oxygen enhancement. This is possibly because oxygen transfer in the lung is not diffusion limited at rest in healthy individuals. This work stresses the importance of using a physiological model to understand results from oxygen enhanced MRI.
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Affiliation(s)
| | - Sandra Diaz
- Medical Radiology, Translational Medicine, Lund University, Malmö, Sweden
| | - Jonas Svensson
- Medical Imaging and Physiology, Skane University Hospital, Lund, Sweden
| | - Per Wollmer
- Clinical Physiology, Translational Medicine, Lund University, Malmö, Sweden
| | - Lars E. Olsson
- Medical Radiation Physics, Translational Medicine, Lund University, Malmö, Sweden
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10
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Triphan SMF, Jobst BJ, Anjorin A, Sedlaczek O, Wolf U, Terekhov M, Hoffmann C, Ley S, Düber C, Biederer J, Kauczor HU, Jakob PM, Wielpütz MO. Reproducibility and comparison of oxygen-enhanced T1 quantification in COPD and asthma patients. PLoS One 2017; 12:e0172479. [PMID: 28207845 PMCID: PMC5312969 DOI: 10.1371/journal.pone.0172479] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 02/06/2017] [Indexed: 12/25/2022] Open
Abstract
T1 maps have been shown to yield useful diagnostic information on lung function in patients with chronic obstructive pulmonary disease (COPD) and asthma, both for native T1 and ΔT1, the relative reduction while breathing pure oxygen. As parameter quantification is particularly interesting for longitudinal studies, the purpose of this work was both to examine the reproducibility of lung T1 mapping and to compare T1 found in COPD and asthma patients using IRSnapShotFLASH embedded in a full MRI protocol. 12 asthma and 12 COPD patients (site 1) and further 15 COPD patients (site 2) were examined on two consecutive days. In each patient, T1 maps were acquired in 8 single breath-hold slices, breathing first room air, then pure oxygen. Maps were partitioned into 12 regions each to calculate average values. In asthma patients, the average T1,RA = 1206ms (room air) was reduced to T1,O2 = 1141ms under oxygen conditions (ΔT1 = 5.3%, p < 5⋅10−4), while in COPD patients both native T1,RA = 1125ms was significantly shorter (p < 10−3) and the relative reduction to T1,O2 = 1081ms on average ΔT1 = 4.2%(p < 10−5). On the second day, with T1,RA = 1186ms in asthma and T1,RA = 1097ms in COPD, observed values were slightly shorter on average in all patient groups. ΔT1 reduction was the least repeatable parameter and varied from day to day by up to 23% in individual asthma and 30% in COPD patients. While for both patient groups T1 was below the values reported for healthy subjects, the T1 and ΔT1 found in asthmatics lies between that of the COPD group and reported values for healthy subjects, suggesting a higher blood volume fraction and better ventilation. However, it could be demonstrated that lung T1 quantification is subject to notable inter-examination variability, which here can be attributed both to remaining contrast agent from the previous day and the increased dependency of lung T1 on perfusion and thus current lung state.
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Affiliation(s)
- Simon M. F. Triphan
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Experimental Physics 5, Julius-Maximilians Universität Würzburg, Würzburg, Germany
- * E-mail:
| | - Bertram J. Jobst
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
| | - Angela Anjorin
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
| | - Oliver Sedlaczek
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
| | - Ursula Wolf
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Radiology, Mainz University Medical School, Mainz, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
| | - Maxim Terekhov
- Department of Radiology, Mainz University Medical School, Mainz, Germany
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Christian Hoffmann
- Department of Radiology, Mainz University Medical School, Mainz, Germany
| | - Sebastian Ley
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Institute for Clinical Radiology, Ludwig Maximilians Universität München, Munich, Germany
| | - Christoph Düber
- Department of Radiology, Mainz University Medical School, Mainz, Germany
| | - Jürgen Biederer
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Radiologie Darmstadt, Department of Radiology Hospital Gross-Gerau, Gross-Gerau, Germany
| | - Hans-Ulrich Kauczor
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
| | - Peter M. Jakob
- Department of Experimental Physics 5, Julius-Maximilians Universität Würzburg, Würzburg, Germany
| | - Mark O. Wielpütz
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
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11
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Dietrich O, Gaass T, Reiser MF. T1 relaxation time constants, influence of oxygen, and the oxygen transfer function of the human lung at 1.5 T—A meta-analysis. Eur J Radiol 2017; 86:252-260. [DOI: 10.1016/j.ejrad.2016.11.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 12/13/2022]
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12
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Kruger SJ, Nagle SK, Couch MJ, Ohno Y, Albert M, Fain SB. Functional imaging of the lungs with gas agents. J Magn Reson Imaging 2016; 43:295-315. [PMID: 26218920 PMCID: PMC4733870 DOI: 10.1002/jmri.25002] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/26/2015] [Indexed: 12/22/2022] Open
Abstract
This review focuses on the state-of-the-art of the three major classes of gas contrast agents used in magnetic resonance imaging (MRI)-hyperpolarized (HP) gas, molecular oxygen, and fluorinated gas--and their application to clinical pulmonary research. During the past several years there has been accelerated development of pulmonary MRI. This has been driven in part by concerns regarding ionizing radiation using multidetector computed tomography (CT). However, MRI also offers capabilities for fast multispectral and functional imaging using gas agents that are not technically feasible with CT. Recent improvements in gradient performance and radial acquisition methods using ultrashort echo time (UTE) have contributed to advances in these functional pulmonary MRI techniques. The relative strengths and weaknesses of the main functional imaging methods and gas agents are compared and applications to measures of ventilation, diffusion, and gas exchange are presented. Functional lung MRI methods using these gas agents are improving our understanding of a wide range of chronic lung diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis in both adults and children.
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Affiliation(s)
- Stanley J. Kruger
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
| | - Scott K. Nagle
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Pediatrics, University of Wisconsin – Madison, WI, U.S.A
| | - Marcus J. Couch
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Biotechnology Program, Lakehead University, Thunder Bay, ON, Canada
| | - Yoshiharu Ohno
- Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Mitchell Albert
- Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada
- Department of Chemistry, Lakehead University, Thunder Bay, ON, Canada
| | - Sean B. Fain
- Department of Medical Physics, University of Wisconsin – Madison, WI, U.S.A
- Department of Radiology, University of Wisconsin – Madison, WI, U.S.A
- Department of Biomedical Engineering, University of Wisconsin – Madison, WI, U.S.A
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13
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Kindvall SS, Diaz S, Svensson J, Wollmer P, Slusarczyk D, Olsson LE. Influence of age and sex on the longitudinal relaxation time, T1, of the lung in healthy never-smokers. J Magn Reson Imaging 2015; 43:1250-7. [DOI: 10.1002/jmri.25085] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/15/2015] [Indexed: 11/12/2022] Open
Affiliation(s)
- Simon S.I. Kindvall
- Medical Radiation Physics, Translational Medicine; Lund University; Malmö Sweden
| | - Sandra Diaz
- Medical Radiology, Translational Medicine; Lund University; Malmö Sweden
| | - Jonas Svensson
- Medical imaging and physiology; Skane University Hospital; Lund Sweden
| | - Per Wollmer
- Clinical Physiology, Translational Medicine; Lund University; Malmö Sweden
| | - Dariusz Slusarczyk
- Medical Radiology, Translational Medicine; Lund University; Malmö Sweden
| | - Lars E. Olsson
- Medical Radiation Physics, Translational Medicine; Lund University; Malmö Sweden
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14
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Renne J, Lauermann P, Hinrichs JB, Schönfeld C, Sorrentino S, Gutberlet M, Jakob P, Haverich A, Warnecke G, Welte T, Wacker FK, Gottlieb J, Vogel-Claussen J. Chronic Lung Allograft Dysfunction: Oxygen-enhanced T1-Mapping MR Imaging of the Lung. Radiology 2015; 276:266-73. [DOI: 10.1148/radiol.15141486] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Miller GW, Mugler JP, Sá RC, Altes TA, Prisk GK, Hopkins SR. Advances in functional and structural imaging of the human lung using proton MRI. NMR IN BIOMEDICINE 2014; 27:1542-56. [PMID: 24990096 PMCID: PMC4515033 DOI: 10.1002/nbm.3156] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/30/2014] [Accepted: 06/01/2014] [Indexed: 05/05/2023]
Abstract
The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed depiction of airway disease. Although there is opportunity for further optimization, such approaches to structural lung imaging are ready for clinical testing.
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Affiliation(s)
- G. Wilson Miller
- Center for In-Vivo Hyperpolarized Gas MRI, Department of Radiology & Medical Imaging
- Department of Biomedical Engineering University of Virginia Charlottesville, VA
- Address correspondence to: Wilson Miller, Radiology Research, 480 Ray C. Hunt Dr., Box 801339, Charlottesville, VA 22908, Phone: 434-243-9216, Fax: 434-924-9435,
| | - John P. Mugler
- Center for In-Vivo Hyperpolarized Gas MRI, Department of Radiology & Medical Imaging
- Department of Biomedical Engineering University of Virginia Charlottesville, VA
| | - Rui C. Sá
- Department of Medicine, Pulmonary Imaging Laboratory, University of California, San Diego La Jolla, CA
| | - Talissa A. Altes
- Center for In-Vivo Hyperpolarized Gas MRI, Department of Radiology & Medical Imaging
| | - G. Kim Prisk
- Department of Medicine, Pulmonary Imaging Laboratory, University of California, San Diego La Jolla, CA
- Department of Radiology, University of California, San Diego La Jolla, CA
| | - Susan R. Hopkins
- Department of Medicine, Pulmonary Imaging Laboratory, University of California, San Diego La Jolla, CA
- Department of Radiology, University of California, San Diego La Jolla, CA
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16
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Zhang WJ, Niven RM, Young SS, Liu YZ, Parker GJM, Naish JH. Dynamic oxygen-enhanced magnetic resonance imaging of the lung in asthma -- initial experience. Eur J Radiol 2014; 84:318-26. [PMID: 25467640 DOI: 10.1016/j.ejrad.2014.10.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/21/2014] [Accepted: 10/25/2014] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To prospectively estimate the feasibility and reproducibility of dynamic oxygen-enhanced magnetic resonance imaging (OE-MRI) in the assessment of regional oxygen delivery, uptake and washout in asthmatic lungs. MATERIALS AND METHODS The study was approved by the National Research Ethics Committee and written informed consent was obtained. Dynamic OE-MRI was performed twice at one month apart on four mild asthmatic patients (23±5 years old, FEV1=96±3% of predicted value) and six severe asthmatic patients (41±12 years old, FEV1=60±14% of predicted value) on a 1.5T MR scanner using a two-dimensional T1-weighted inversion-recovery turbo spin echo sequence. The enhancing fraction (EF), the maximal change in the partial pressure of oxygen in lung tissue (ΔPO2max_l) and arterial blood of the aorta (ΔPO2max_a), and the oxygen wash-in (τup_l, τup_a) and wash-out (τdown_l, τdown_a) time constants were extracted and compared between groups using the independent-samples t-test (two-tailed). Correlations between imaging readouts and clinical measurements were assessed by Pearson's correlation analysis. Bland-Altman analysis was used to estimate the levels of agreement between the repeat scans and the intra-observer agreement in the MR imaging readouts. RESULTS The severe asthmatic group had significantly smaller EF (70±16%) and median ΔPO2max_l (156±52mmHg) and significantly larger interquartile range of τup_l (0.84±0.26min) than the mild asthmatic group (95±3%, P=0.014; 281±40mmHg, P=0.004; 0.20±0.07min, P=0.001, respectively). EF, median ΔPO2max_l and τdown_l and the interquartile range of τup_l and τdown_l were significantly correlated with age and pulmonary function test parameters (r=-0.734 to -0.927, 0.676-0.905; P=0.001-0.045). Median ΔPO2max_l was significantly correlated with ΔPO2max_a (r=0.745, P=0.013). Imaging readouts showed good one-month reproducibility and good intra-observer agreement (mean bias between repeated scans and between two observations did not significantly deviate from zero). CONCLUSIONS Dynamic OE-MRI is feasible in asthma and sensitive to the severity of disease. The technique provides indices related to regional oxygen delivery, uptake and washout that show good one month reproducibility and intra-observer agreement.
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Affiliation(s)
- Wei-Juan Zhang
- Centre for Imaging Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK; Biomedical Imaging Institute, The University of Manchester, Oxford Road, Manchester M13 9PT, UK.
| | - Robert M Niven
- North West Lung Research Centre, University Hospital of South Manchester, Southmoor Road, Manchester M23 9LT, UK.
| | - Simon S Young
- Personalised Healthcare and Biomarkers, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TF, UK.
| | - Yu-Zhen Liu
- Personalised Healthcare and Biomarkers, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TF, UK.
| | - Geoffrey J M Parker
- Centre for Imaging Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK; Biomedical Imaging Institute, The University of Manchester, Oxford Road, Manchester M13 9PT, UK; Bioxydyn Limited, Rutherford House, Pencroft Way, Manchester M15 6SZ, UK.
| | - Josephine H Naish
- Centre for Imaging Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK; Biomedical Imaging Institute, The University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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17
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Renne J, Lauermann P, Hinrichs J, Schönfeld C, Sorrentino S, Gutberlet M, Jakob P, Wacker F, Vogel-Claussen J. Clinical use of oxygen-enhanced T1 mapping MRI of the lung: reproducibility and impact of closed versus loose fit oxygen delivery system. J Magn Reson Imaging 2013; 41:60-6. [PMID: 24339056 DOI: 10.1002/jmri.24535] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 11/14/2013] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To evaluate the reproducibility of oxygen-enhanced magnetic resonance imaging (MRI), and the influence of different gas delivery methods, in a clinical environment. MATERIALS AND METHODS Twelve healthy volunteers were examined on two visits with an inversion recovery snapshot fast low angle shot sequence on a 1.5 T system. Coronal slices were obtained breathing room air as well as 100% oxygen with a flow rate of 15 L/min. For oxygen delivery a standard nontight face mask and a full closed air-cushion face mask were used. T1 relaxation times and the oxygen transfer function (OTF) were calculated. RESULTS The mean T1 values did not change significantly between the two visits (P > 0.05). The T1 values breathing 100% oxygen obtained using the full closed mask were significantly lower (1093 ± 38 msec; P < 0.05) compared to the standard mask (1157 ± 52 msec). Accordingly, the OTF was significantly higher for the full closed mask (P < 0.05). The OTF changed significantly on the second visit using the standard mask (P < 0.05). The full closed mask showed lower interindividual variation for both the T1 values (3.5% vs. 4.5%) as well as the OTF (12.4% vs. 22.0%) and no difference of the OTF on the second visit (P > 0.05). CONCLUSION Oxygen-enhanced T1 mapping MRI produces reproducible data when using a full closed face mask.
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Affiliation(s)
- Julius Renne
- Diagnostic and Interventional Radiology, Hannover Medical School, Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
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18
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Zurek M, Johansson E, Risse F, Alamidi D, Olsson LE, Hockings PD. Accurate T
1
mapping for oxygen-enhanced MRI in the mouse lung using a segmented inversion-recovery ultrashort echo-time sequence. Magn Reson Med 2013; 71:2180-5. [DOI: 10.1002/mrm.24876] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 05/24/2013] [Accepted: 06/17/2013] [Indexed: 11/08/2022]
Affiliation(s)
- M. Zurek
- AstraZeneca, Personalized Healthcare and Biomarkers, In vivo Biomarkers; Mölndal Sweden
| | - E. Johansson
- AstraZeneca, Personalized Healthcare and Biomarkers, In vivo Biomarkers; Mölndal Sweden
| | - F. Risse
- AstraZeneca, Personalized Healthcare and Biomarkers, In vivo Biomarkers; Mölndal Sweden
| | - D. Alamidi
- Department of Radiation Physics; Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
| | - L. E. Olsson
- Department of Medical Radiation Physics; IKVM, Lund University; Malmö Sweden
| | - P. D. Hockings
- AstraZeneca, Personalized Healthcare and Biomarkers, In vivo Biomarkers; Mölndal Sweden
- MedTech West; Chalmers University of Technology; Gothenburg Sweden
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19
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Henderson AC, Sá RC, Theilmann RJ, Buxton RB, Prisk GK, Hopkins SR. The gravitational distribution of ventilation-perfusion ratio is more uniform in prone than supine posture in the normal human lung. J Appl Physiol (1985) 2013; 115:313-24. [PMID: 23620488 DOI: 10.1152/japplphysiol.01531.2012] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The gravitational gradient of intrapleural pressure is suggested to be less in prone posture than supine. Thus the gravitational distribution of ventilation is expected to be more uniform prone, potentially affecting regional ventilation-perfusion (Va/Q) ratio. Using a novel functional lung magnetic resonance imaging technique to measure regional Va/Q ratio, the gravitational gradients in proton density, ventilation, perfusion, and Va/Q ratio were measured in prone and supine posture. Data were acquired in seven healthy subjects in a single sagittal slice of the right lung at functional residual capacity. Regional specific ventilation images quantified using specific ventilation imaging and proton density images obtained using a fast gradient-echo sequence were registered and smoothed to calculate regional alveolar ventilation. Perfusion was measured using arterial spin labeling. Ventilation (ml·min(-1)·ml(-1)) images were combined on a voxel-by-voxel basis with smoothed perfusion (ml·min(-1)·ml(-1)) images to obtain regional Va/Q ratio. Data were averaged for voxels within 1-cm gravitational planes, starting from the most gravitationally dependent lung. The slope of the relationship between alveolar ventilation and vertical height was less prone than supine (-0.17 ± 0.10 ml·min(-1)·ml(-1)·cm(-1) supine, -0.040 ± 0.03 prone ml·min(-1)·ml(-1)·cm(-1), P = 0.02) as was the slope of the perfusion-height relationship (-0.14 ± 0.05 ml·min(-1)·ml(-1)·cm(-1) supine, -0.08 ± 0.09 prone ml·min(-1)·ml(-1)·cm(-1), P = 0.02). There was a significant gravitational gradient in Va/Q ratio in both postures (P < 0.05) that was less in prone (0.09 ± 0.08 cm(-1) supine, 0.04 ± 0.03 cm(-1) prone, P = 0.04). The gravitational gradients in ventilation, perfusion, and regional Va/Q ratio were greater supine than prone, suggesting an interplay between thoracic cavity configuration, airway and vascular tree anatomy, and the effects of gravity on Va/Q matching.
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Affiliation(s)
- A Cortney Henderson
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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20
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Abstract
Oxygen-enhanced MRI has been shown to be a viable alternative to hyperpolarized gases for pulmonary imaging. The changes in the relaxation times due to hyperoxic conditions in the blood pool induced by inhalation of pure oxygen have produced sufficient signal changes for imaging applications. This is a safe and low-cost alternative for contrast-enhanced imaging. The application of oxygen-enhanced MRI in brain imaging has been much less studied. In this study, we investigated the changes in the relaxation times in the brain due to inhalation of pure oxygen in a rodent model. We also assessed the effects of reduced blood flow due to hyperoxic conditions. Despite the reduced blood flow, significant changes in T1, T2, and T2* relaxation times were detected. We conclude that oxygen-enhanced MRI can be used in rodent models of disease.
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22
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Gensler D, Fidler F, Ehses P, Warmuth M, Reiter T, Düring M, Ritter O, Ladd ME, Quick HH, Jakob PM, Bauer WR, Nordbeck P. MR safety: Fast T
1
thermometry of the RF-induced heating of medical devices. Magn Reson Med 2012; 68:1593-9. [PMID: 22287286 DOI: 10.1002/mrm.24171] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 12/01/2011] [Accepted: 12/29/2011] [Indexed: 11/11/2022]
Affiliation(s)
- D Gensler
- Research Center for Magnetic Resonance Bavaria e.V., Würzburg, Germany.
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23
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Maxien D, Dietrich O, Thieme SF, Förster S, Behr J, Reiser MF, Nikolaou K. Value of oxygen-enhanced MRI of the lungs in patients with pulmonary hypertension: A qualitative and quantitative approach. J Magn Reson Imaging 2011; 35:86-94. [DOI: 10.1002/jmri.22740] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 07/14/2011] [Indexed: 11/05/2022] Open
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Huang C, Graff CG, Clarkson EW, Bilgin A, Altbach MI. T2 mapping from highly undersampled data by reconstruction of principal component coefficient maps using compressed sensing. Magn Reson Med 2011; 67:1355-66. [PMID: 22190358 DOI: 10.1002/mrm.23128] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 06/14/2011] [Accepted: 07/08/2011] [Indexed: 12/30/2022]
Abstract
Recently, there has been an increased interest in quantitative MR parameters to improve diagnosis and treatment. Parameter mapping requires multiple images acquired with different timings usually resulting in long acquisition times. While acquisition time can be reduced by acquiring undersampled data, obtaining accurate estimates of parameters from undersampled data is a challenging problem, in particular for structures with high spatial frequency content. In this work, principal component analysis is combined with a model-based algorithm to reconstruct maps of selected principal component coefficients from highly undersampled radial MRI data. This novel approach linearizes the cost function of the optimization problem yielding a more accurate and reliable estimation of MR parameter maps. The proposed algorithm--reconstruction of principal component coefficient maps using compressed sensing--is demonstrated in phantoms and in vivo and compared with two other algorithms previously developed for undersampled data.
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Affiliation(s)
- Chuan Huang
- Department of Mathematics, University of Arizona, Tucson, Arizona 85724, USA
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25
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Dietrich O, Attenberger UI, Ingrisch M, Maxien D, Peller M, Nikolaou K, Reiser MF. Analysis of signal dynamics in oxygen-enhanced magnetic resonance imaging. Invest Radiol 2010; 45:165-73. [PMID: 20195161 DOI: 10.1097/rli.0b013e3181cd74e2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Oxygen-enhanced MRI (O2-MRI) is frequently based on a block paradigm consisting of a series of consecutive T1-weighted scans acquired during alternating blocks with inhalation of room air and of pure oxygen. This design results in a complex signal-time course for each pixel, which displays the oxygen wash-in and wash-out processes and provides spatially resolved information about the lung function. The purpose of the present study was to optimize the signal-time-course analysis to extract (pixelwise) the maximum amount of information from the acquired data, and to introduce an appropriate cross-correlation approach for data sets containing the oxygen wash-in and wash-out periods. MATERIALS AND METHODS O2-MRI data of 11 healthy volunteers were acquired with a multislice inversion-recovery single-shot turbo-spin-echo sequence at 1.5 Tesla; lung and spleen were manually segmented on all 44 acquired slices. Six different model functions were pixelwise fitted to the data and compared using the Akaike information criterion. Four different reference functions were compared for cross-correlation analysis. RESULTS The optimal model function is a piecewise exponential function (median enhancement in lung/spleen: 16.3%/14.8%) with different time constants for wash-in (29.4 seconds/72.7 seconds) and wash-out (25.1 seconds/29.6 seconds). As a new parameter, it contains the delay between switching the gas supply and the onset of the signal change (4.8 seconds/24.5 seconds). Optimal cross-correlation results were obtained with a piecewise exponential reference function, which was temporally shifted to maximize the correlation, yielding median correlation coefficients of 0.694 and 0.878, median time delays of 7.5 seconds and 38.6 seconds, and median fractions of oxygen-activated pixels of 83.6% and 92.2% in the lung and the spleen, respectively. CONCLUSIONS It was demonstrated that the pixelwise assessment of O2-MRI data are optimally performed with piecewise exponential functions. Cross-correlation analysis with a piecewise exponential reference function results in significantly higher fractions of oxygen-activated pixels than with rectangular functions.
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Affiliation(s)
- Olaf Dietrich
- Department of Clinical Radiology-Grosshadern, LMU Ludwig Maximilian University of Munich, Munich, Germany.
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26
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Blume U, Orbell J, Waltham M, Smith A, Razavi R, Schaeffter T. 3D T(1)-mapping for the characterization of deep vein thrombosis. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2009; 22:375-83. [PMID: 19946791 DOI: 10.1007/s10334-009-0189-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 11/05/2009] [Accepted: 11/12/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE The aim of this work was to investigate fast T (1)-mapping for the characterization of deep vein thrombosis (DVT). METHODS The accuracy and reproducibility of the T (1)-mapping sequence was tested in phantoms and in 8 healthy volunteers on a 1.5 T clinical scanner using a 32-channel array coil. Furthermore, the feasibility of the technique was tested in 5 patients diagnosed with DVT by measuring the volume and T (1) values of the thrombus at 5 time points over a period of 6 months. RESULTS The results of the phantom and volunteer study showed a high accuracy and reproducibility for the quantification of T (1). The resolution of the T (1)-maps was high enough to identify small anatomical structures. T (1) values derived for normal blood and various other tissues were comparable to those reported in the literature. In all patients, the T (1) times of thrombi showed decreased values (T (1) = 843 +/- 91 ms) in the acute phase and recovered back to normal values of blood (T (1) = 1,317 +/- 36 ms) after 6 months. CONCLUSIONS Measurement of all relevant T (1) values of acute thrombi and normal blood achieved accurate and reproducible results in vivo. Fast T (1) quantification of the thrombus can provide information about tissue characteristics such as thrombus resolution. Such a quantitative MRI technique may be valuable in studying the factors that influence natural resolution and in evaluating treatment effects that enhance this process.
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Affiliation(s)
- Ulrike Blume
- Division of Imaging Sciences, The Rayne Institute, King's College London, St Thomas Hospital, 4th Floor Lambeth Wing, London SE1 7EH, UK.
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Scholz AW, Wolf U, Fabel M, Weiler N, Heussel CP, Eberle B, David M, Schreiber WG. Comparison of magnetic resonance imaging of inhaled SF6 with respiratory gas analysis. Magn Reson Imaging 2009; 27:549-56. [DOI: 10.1016/j.mri.2008.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 08/26/2008] [Accepted: 08/27/2008] [Indexed: 10/21/2022]
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28
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Preibisch C, Deichmann R. Influence of RF spoiling on the stability and accuracy of T1 mapping based on spoiled FLASH with varying flip angles. Magn Reson Med 2009; 61:125-35. [PMID: 19097220 DOI: 10.1002/mrm.21776] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There is increasing interest in quantitative T(1) mapping techniques for a variety of applications. Several methods for T(1) quantification have been described. The acquisition of two spoiled gradient-echo data sets with different flip angles allows for the calculation of T(1) maps with a high spatial resolution and a relatively short experimental duration. However, the method requires complete spoiling of transverse magnetization. To achieve this goal, RF spoiling has to be applied. In this work it is investigated whether common RF spoiling techniques are sufficiently effective to allow for accurate T(1) quantification. It is shown that for most phase increments the apparent T(1) can deviate considerably from the true value. Correct results may be achieved with phase increments of 118.2 degrees or 121.8 degrees. However, for these values the method suffers from instabilities. In contrast, stable results are obtained with a phase increment of 50 degrees. An algorithm is presented that allows for the calculation of corrected T(1) maps from the apparent values. The method is tested both in phantom experiments and in vivo by acquiring whole-brain T(1) maps of the human brain.
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Affiliation(s)
- C Preibisch
- Brain Imaging Center, University Hospital, Frankfurt, Germany.
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Martin AR, Thompson RB, Finlay WH. MRI measurement of regional lung deposition in mice exposed nose-only to nebulized superparamagnetic iron oxide nanoparticles. J Aerosol Med Pulm Drug Deliv 2009; 21:335-42. [PMID: 18800881 DOI: 10.1089/jamp.2008.0698] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Superparamagnetic iron oxide nanoparticles show potential in magnetic targeting of inhaled aerosols to localized sites within the lung. These particles are also used as contrast agents in magnetic resonance imaging (MRI). In the present work, we examine the feasibility of measuring regional lung deposition of iron oxide nanoparticles using MRI. Mice were exposed nose-only to nebulized superparamagnetic iron oxide nanoparticles. The droplet size distribution in the inhalation chamber was measured using a time-of-flight device. Regional concentrations of iron in the left and right lung were assessed with MRI by measuring the longitudinal relaxation times (T(1)) of the lung tissue in exposed mice, compared to a baseline group. Regional concentrations of iron in the lungs of the mice ranged from 1.1 +/- 0.8 microg/cm(3) (mean +/- one standard deviation, n = 6) in peripheral lung regions to 2.7 +/- 1.4 microg/cm(3) in the central lung, with no significant difference between the left and right lung. The nebulized droplets in the inhalation chamber had mass median aerodynamic diameter (MMAD) of 5.6 +/- 0.8 microm, with a geometric standard deviation (GSD) of 1.30 +/- 0.03 (both values expressed as mean +/- one standard deviation, n = 6). MRI shows promise for in vivo measurement of regional lung concentrations of superparamagnetic iron oxide nanoparticles, and may be useful in studies of lung deposition and clearance.
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Affiliation(s)
- Andrew R Martin
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada
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Mosbah K, Ruiz-Cabello J, Berthezène Y, Crémillieux Y. Aerosols and gaseous contrast agents for magnetic resonance imaging of the lung. CONTRAST MEDIA & MOLECULAR IMAGING 2008; 3:173-90. [DOI: 10.1002/cmmi.252] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Watt K, Bishop J, Nieman B, Henkelman R, Chen X. Oxygen-enhanced MR imaging of mice lungs. Magn Reson Med 2008; 59:1412-21. [DOI: 10.1002/mrm.21517] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pracht ED, Arnold JF, Seiberlich N, Kotas M, Flentje M, Jakob PM. Oxygen-enhanced Proton Magnetic Resonance Imaging of the Human Lung. Cancer Imaging 2008. [DOI: 10.1016/b978-012374212-4.50031-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Nichols MB, Paschal CB. Measurement of longitudinal (T1) relaxation in the human lung at 3.0 Tesla with tissue-based and regional gradient analyses. J Magn Reson Imaging 2007; 27:224-8. [DOI: 10.1002/jmri.21243] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Arnold JFT, Kotas M, Fidler F, Pracht ED, Flentje M, Jakob PM. Quantitative regional oxygen transfer imaging of the human lung. J Magn Reson Imaging 2007; 26:637-45. [PMID: 17685416 DOI: 10.1002/jmri.21033] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To demonstrate that the use of nonquantitative methods in oxygen-enhanced (OE) lung imaging can be problematic and to present a new approach for quantitative OE lung imaging, which fulfills the requirements for easy application in clinical practice. MATERIALS AND METHODS A total of 10 healthy volunteers and three non-small-cell lung cancer (NSCLC) patients were examined using a 1.5T scanner. OE imaging was performed using a snapshot fast low-angle shot (FLASH) T(1)-mapping technique (TE = 1.4 msec, TR = 3.5 msec) as well as a series of T(1)-weighted inversion recovery (IR) half- Fourier acquisition single-shot turbo spin-echo (HASTE) (TE(effective) = 43 msec, TE(inter) = 4.2 msec, and inversion time [TI] = 1200 msec) images. Semiquantitative relative signal enhancement ratios (RER) of T(1)-weighted images before and after inhalation of oxygen-enriched gas were compared to the quantitative change in T(1). A hybrid method is proposed that combines the advantages of T(1)-weighted imaging with the quantification provided by T(1)-mapping. To this end, the IR-HASTE images were transformed into quantitative parameter maps. To prevent mismatching and incorrect parameter maps, retrospective image selection was performed using a postprocessing navigator technique. RESULTS The RER was dependent on the intrinsic values of T(1) in the lung. Quantitative parameters, such as the decrease of T(1) after switching the breathing gas, were more suited to oxygen transfer quantification than to relative signal enhancement. The mean T(1) value during inhalation of room air (T(1,room)) for the volunteers was 1260 msec. This value decreased by about 10% after switching the breathing gas to carbogen. For the patients, the mean T(1,room) value was 1182 msec, which decreased by about 7% when breathing carbogen. The parameter maps generated using the proposed hybrid method deviated, on average, only about 1% from the T(1)-maps. CONCLUSION For the purpose of intersubject comparison, OE lung imaging should be performed quantitatively. The proposed hybrid technique produced reliable quantitative results in a short amount of time and, therefore, is suited for clinical use.
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Hopkins SR, Levin DL, Emami K, Kadlecek S, Yu J, Ishii M, Rizi RR. Advances in magnetic resonance imaging of lung physiology. J Appl Physiol (1985) 2006; 102:1244-54. [PMID: 17158249 DOI: 10.1152/japplphysiol.00738.2006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review presents an overview of some recent magnetic resonance imaging (MRI) techniques for measuring aspects of local physiology in the lung. MRI is noninvasive, relatively high resolution, and does not expose subjects to ionizing radiation. Conventional MRI of the lung suffers from low signal intensity caused by the low proton density and the large degree of microscopic field inhomogeneity that degrades the magnetic resonance signal and interferes with image acquisition. However, in recent years, there have been rapid advances in both hardware and software design, allowing these difficulties to be minimized. This review focuses on some newer techniques that measure regional perfusion, ventilation, gas diffusion, ventilation-to-perfusion ratio, partial pressure of oxygen, and lung water. These techniques include contrast-enhanced and arterial spin-labeling techniques for measuring perfusion, hyperpolarized gas techniques for measuring regional ventilation, and apparent diffusion coefficient and multiecho and gradient echo techniques for measuring proton density and lung water. Some of the major advantages and disadvantages of each technique are discussed. In addition, some of the physiological issues associated with making measurements are discussed, along with strategies for understanding large and complex data sets.
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Affiliation(s)
- Susan R Hopkins
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA.
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Dietrich O, Losert C, Attenberger U, Reuter C, Fasol U, Peller M, Nikolaou K, Reiser MF, Schoenberg SO. Sauerstoff-MRT der Lunge: Optimierte Berechnung von Differenzbildern. Radiologe 2006; 46:300-2, 304-8. [PMID: 16437238 DOI: 10.1007/s00117-005-1324-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND In oxygen-enhanced lung MRI, difference maps of acquisitions during inhalation of room air and pure oxygen are calculated to assess lung function. The purpose of this study was to analyze how the calculation of these difference maps depends on the delayed signal change after switching the gas supply. METHODS Ten healthy volunteers were examined with an ECG and respiratory-triggered T1-weighting inversion recovery HASTE sequence with parallel imaging. Four blocks with 20 repetitions of up to 6 coronal slices were continuously acquired; in blocks 1 and 3 room air was supplied, in blocks 2 and 4 oxygen. Data were postprocessed, discarding between 0 and 19 repetitions after each change of gas supply before calculating the relative signal difference. RESULTS The averaged relative signal difference increases from 9.4 to 17.4% when the number of discarded acquisitions increases; the ratio of signal difference and spatial standard deviation reaches a maximum at 5-8 discarded acquisitions. CONCLUSIONS An optimized ratio of signal difference and statistical error is found if about 5-8 of 20 respiratory-triggered repetitions are discarded after each change of gas supply for the calculation of difference maps.
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Affiliation(s)
- O Dietrich
- Institut für Klinische Radiologie - Grosshadern, Klinikum der Ludwig-Maximilians-Universität, München.
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Abstract
A sequence for the acquisition of high-resolution T1 maps, based on magnetization-prepared multislice fast low-angle shot (FLASH) imaging, is presented. In contrast to similar methods, no saturation pulses are used, resulting in an increased dynamic range of the relaxation process. Furthermore, it is possible to acquire data during all relaxation delays because only slice-selective radiofrequency (RF) pulses are used for inversion and excitation. This allows for a reduction of the total acquisition time, or scanning with a reduced bandwidth, which improves the signal-to-noise ratio (SNR). The method generates quantitative T1 maps with an in-plane resolution of 1 mm, slice thickness of 4 mm, and whole-brain coverage in a clinically acceptable imaging time of about 19 s per slice. It is shown that the use of off-center RF pulses does not result in imperfect inversion or magnetization transfer (MT) effects. In addition, an improved fitting algorithm based on smoothed flip angle maps is presented and tested successfully.
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Affiliation(s)
- Ralf Deichmann
- Wellcome Department of Imaging Neuroscience, Institute of Neurology, London, UK.
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Pracht ED, Arnold JFT, Wang T, Jakob PM. Oxygen-enhanced proton imaging of the human lung usingT2*. Magn Reson Med 2005; 53:1193-6. [PMID: 15844155 DOI: 10.1002/mrm.20448] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Magnetic susceptibility gradients caused by tissue/air interfaces lead to very short T(2)* times in the human lung. These susceptibility gradients are dependent on the magnetic susceptibility of the respiratory gas and therefore should influence T(2)* relaxation. In this work, a technique for quantitative T(2)* mapping of the human lung during one breath hold is presented. Using this method, the lung T(2)* relaxation time was measured under normoxic (room air, 21% O(2)) and hyperoxic (100% O(2)) conditions to verify this assumption. The mean T(2)* difference between room air and 100% O(2) is about 10% and contains ventilation information, since only ventilated regions contribute to signal change due to different susceptibility gradients.
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Affiliation(s)
- Eberhard D Pracht
- Department of Experimental Physics 5, University of Würzburg, Germany.
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