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  • 1
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    Magnetic resonance elastography of the lung parenchyma in an in situ porcine model with a noninvasive mechanical driver: Correlation of shear stiffness with trans‐respiratory system pressures
    Wiley ; 2012
    In:  Magnetic Resonance in Medicine Vol. 67, No. 1 ( 2012-01), p. 210-217
    Details
    In: Magnetic Resonance in Medicine, Wiley, Vol. 67, No. 1 ( 2012-01), p. 210-217
    Abstract: Quantification of the mechanical properties of lung parenchyma is an active field of research due to the association of this metric with normal function, disease initiation and progression. A phase contrast MRI‐based elasticity imaging technique known as magnetic resonance elastography is being investigated as a method for measuring the shear stiffness of lung parenchyma. Previous experiments performed with small animals using invasive drivers in direct contact with the lungs have indicated that the quantification of lung shear modulus with 1 H based magnetic resonance elastography is feasible. This technique has been extended to an in situ porcine model with a noninvasive mechanical driver placed on the chest wall. This approach was tested to measure the change in parenchymal stiffness as a function of airway opening pressure ( P ao ) in 10 adult pigs. In all animals, shear stiffness was successfully quantified at four different P ao values. Mean (±STD error of mean) pulmonary parenchyma density corrected stiffness values were calculated to be 1.48 (±0.09), 1.68 (±0.10), 2.05 (±0.13), and 2.23 (±0.17) kPa for P ao values of 5, 10, 15, and 20 cm H2O, respectively. Shear stiffness increased with increasing P ao , in agreement with the literature. It is concluded that in an in situ porcine lung shear stiffness can be quantitated with 1 H magnetic resonance elastography using a noninvasive mechanical driver and that it is feasible to measure the change in shear stiffness due to change in P ao . Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    URL: Article
    DOI: 10.1002/mrm.v67.1
    DOI: 10.1002/mrm.22976
    Language: English
    Publisher: Wiley
    Publication Date: 2012
    detail.hit.zdb_id: 1493786-4
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  • 2
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    Estimation of the absolute shear stiffness of human lung parenchyma using 1 H spin echo, echo planar MR elastography
    Wiley ; 2014
    In:  Journal of Magnetic Resonance Imaging Vol. 40, No. 5 ( 2014-11), p. 1230-1237
    Details
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 40, No. 5 ( 2014-11), p. 1230-1237
    Abstract: To develop a rapid proton MR elastography (MRE) technique that can quantify the absolute shear stiffness of lung parenchyma, to investigate the ability to differentiate respiration‐dependent stiffness variations of the lung, and to demonstrate clinical feasibility. Materials and Methods A spin‐echo echo planar imaging MRE sequence (SE‐EPI MRE) with a very short echo time was developed and tested in a series of five healthy volunteers at three different lung volumes: (i) residual volume (RV), (ii) total lung capacity (TLC), (iii) and midway between RV and TLC (MID). At each volume, lung density was quantified using a MR‐based density mapping sequence. For reference, data were acquired using the previously described spin‐echo lung MRE sequence (SE‐MRE). MRE data were also acquired in a patient with proven Idiopathic Pulmonary Fibrosis (IPF) to test clinical feasibility. Results The SE‐EPIMRE sequence reduced total acquisition time by a factor of 2 compared with the SE‐MRE sequence. Lung parenchyma median shear stiffness for the 5 volunteers quantified with the SE‐EPI MRE sequence was 0.9 kPa, 1.1 kPa, and 1.6 kPa at RV, MID, and TLC, respectively. The corresponding values obtained with the SE‐MRE sequence were 0.9 kPa, 1.1 kPa, and 1.5 kPa. Absolute shear stiffness was also successfully measured in the IPF patient. Conclusion The results indicate that stiffness variations due to respiration could be measured with the SE‐EPIMRE technique and were equivalent to values generated by the previously described SE‐MRE approach. Preliminary data obtained from the patient demonstrate clinical feasibility. J. Magn. Reson. Imaging 2014;40:1230–1237 . © 2013 Wiley Periodicals, Inc .
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    URL: Article
    DOI: 10.1002/jmri.v40.5
    DOI: 10.1002/jmri.24479
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 1497154-9
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  • 3
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    Quantitative assessment of lung stiffness in patients with interstitial lung disease using MR elastography
    Wiley ; 2017
    In:  Journal of Magnetic Resonance Imaging Vol. 46, No. 2 ( 2017-08), p. 365-374
    Details
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 46, No. 2 ( 2017-08), p. 365-374
    Abstract: To investigate the use of magnetic resonance elastography (MRE) in the quantitative assessment of pulmonary fibrosis by comparing quantitative shear stiffness measurements of lung parenchyma in patients diagnosed with fibrotic interstitial lung disease (ILD) and healthy controls. Materials and Methods A 1.5T spin‐echo, echo planar imaging MRE (SE‐EPI MRE) pulse sequence was utilized to assess absolute lung shear stiffness in 15 patients with diagnosed ILD and in 11 healthy controls. Data were collected at residual volume (RV) and total lung capacity (TLC). Spirometry data were obtained immediately prior to scanning. To test for statistical significance between RV and TLC shear stiffness estimates a two‐sample t ‐test was performed. To assess variability within individual subject shear stiffness estimates, the intraclass correlation coefficient (ICC) and Krippendorff's alpha were calculated. Results Patients with ILD exhibited an average (±1 standard deviation) shear stiffness of 2.74 (±0.896) kPa at TLC and 1.32 (±0.300) kPa at RV. The corresponding values for healthy individuals were 1.33 (±0.195) kPa and 0.849 (±0.250) kPa, respectively. The difference in shear stiffness between RV and TLC was statistically significant ( P 〈 0.001). At TLC, the ICC and alpha values were 0.909 and 0.887, respectively. At RV, the ICC and alpha values were 0.852 and 0.862, respectively. Conclusion In subjects with known fibrotic interstitial lung disease, parenchymal shear stiffness is increased when compared to normal controls at both RV and TLC, with TLC demonstrating the most significant difference. MRE‐derived parenchymal shear stiffness is a promising new noninvasive imaging‐based biomarker of interstitial lung disease. Level of Evidence : 1 Technical Efficacy : Stage 2 J. MAGN. RESON. IMAGING 2017;46:365–374
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    URL: Article
    DOI: 10.1002/jmri.v46.2
    DOI: 10.1002/jmri.25579
    Language: English
    Publisher: Wiley
    Publication Date: 2017
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  • 4
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    MR elastography of the lung with hyperpolarized 3 He : Measurement of Shear Modulus of Lung
    Wiley ; 2008
    In:  Magnetic Resonance in Medicine Vol. 59, No. 1 ( 2008-01), p. 14-18
    Details
    In: Magnetic Resonance in Medicine, Wiley, Vol. 59, No. 1 ( 2008-01), p. 14-18
    Type of Medium: Online Resource
    ISSN: 0740-3194
    URL: Issue
    URL: Article
    DOI: 10.1002/mrm.v59:1
    DOI: 10.1002/mrm.21465
    Language: English
    Publisher: Wiley
    Publication Date: 2008
    detail.hit.zdb_id: 1493786-4
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  • 5
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    Magnetic resonance assessment of parenchymal elasticity in normal and edematous, ventilator-injured lung
    American Physiological Society ; 2012
    In:  Journal of Applied Physiology Vol. 113, No. 4 ( 2012-08-15), p. 666-676
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 113, No. 4 ( 2012-08-15), p. 666-676
    Abstract: Magnetic resonance elastography (MRE) is a MR imaging method capable of spatially resolving the intrinsic mechanical properties of normal lung parenchyma. We tested the hypothesis that the mechanical properties of edematous lung exhibit local properties similar to those of a fluid-filled lung at transpulmonary pressures (P tp ) up to 25 cm H 2 O. Pulmonary edema was induced in anesthetized female adult Sprague-Dawley rats by mechanical ventilation to a pressure of 40 cm H 2 O for ∼30 min. Prior to imaging the wet weight of each ex vivo lung set was measured. MRE, high-resolution T 1 -weighted spin echo and T 2 * gradient echo data were acquired at each P tp for both normal and injured ex vivo lungs. At P tp s of 6 cm H 2 O and greater, the shear stiffness of normal lungs was greater than injured lungs ( P ≤ 0.0003). For P tp s up to 12 cm H 2 O, shear stiffness was equal to 1.00, 1.07, 1.16, and 1.26 kPa for the injured and 1.31, 1.89, 2.41, and 2.93 kPa for normal lungs at 3, 6, 9, and 12 cm H 2 O, respectively. For injured lungs MRE magnitude signal and shear stiffness within regions of differing degrees of alveolar flooding were calculated as a function of P tp . Differences in shear stiffness were statistically significant between groups ( P 〈 0.001) with regions of lower magnitude signal being stiffer than those of higher signal. These data demonstrate that when the alveolar space filling material is fluid, MRE-derived parenchymal shear stiffness of the lung decreases, and the lung becomes inherently softer compared with normal lung.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.01628.2011
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2012
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 6
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    Quantitative assessment of lung stiffness in patients with interstitial lung disease using MR elastography
    Wiley ; 2017
    In:  Journal of Magnetic Resonance Imaging Vol. 46, No. 2 ( 2017-08)
    Details
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 46, No. 2 ( 2017-08)
    Abstract: To investigate the use of magnetic resonance elastography (MRE) in the quantitative assessment of pulmonary fibrosis by comparing quantitative shear stiffness measurements of lung parenchyma in patients diagnosed with fibrotic interstitial lung disease (ILD) and healthy controls. Materials and Methods A 1.5T spin‐echo, echo planar imaging MRE (SE‐EPI MRE) pulse sequence was utilized to assess absolute lung shear stiffness in 15 patients with diagnosed ILD and in 11 healthy controls. Data were collected at residual volume (RV) and total lung capacity (TLC). Spirometry data were obtained immediately prior to scanning. To test for statistical significance between RV and TLC shear stiffness estimates a two‐sample t ‐test was performed. To assess variability within individual subject shear stiffness estimates, the intraclass correlation coefficient (ICC) and Krippendorff's alpha were calculated. Results Patients with ILD exhibited an average (±1 standard deviation) shear stiffness of 2.74 (±0.896) kPa at TLC and 1.32 (±0.300) kPa at RV. The corresponding values for healthy individuals were 1.33 (±0.195) kPa and 0.849 (±0.250) kPa, respectively. The difference in shear stiffness between RV and TLC was statistically significant ( P 〈 0.001). At TLC, the ICC and alpha values were 0.909 and 0.887, respectively. At RV, the ICC and alpha values were 0.852 and 0.862, respectively. Conclusion In subjects with known fibrotic interstitial lung disease, parenchymal shear stiffness is increased when compared to normal controls at both RV and TLC, with TLC demonstrating the most significant difference. MRE‐derived parenchymal shear stiffness is a promising new noninvasive imaging‐based biomarker of interstitial lung disease. Level of Evidence:1 J. MAGN. RESON. IMAGING 2017;46:1–1
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    URL: Article
    DOI: 10.1002/jmri.v46.2
    DOI: 10.1002/jmri.25805
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 1497154-9
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  • 7
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    Feasibility of quantifying the mechanical properties of lung parenchyma in a small-animal model using 1 H magnetic resonance elastography (MRE)
    Wiley ; 2009
    In:  Journal of Magnetic Resonance Imaging Vol. 29, No. 4 ( 2009-04), p. 838-845
    Details
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 29, No. 4 ( 2009-04), p. 838-845
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    URL: Article
    DOI: 10.1002/jmri.v29:4
    DOI: 10.1002/jmri.21720
    Language: English
    Publisher: Wiley
    Publication Date: 2009
    detail.hit.zdb_id: 1497154-9
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  • 8
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    MR elastography of human lung parenchyma: Technical development, theoretical modeling and in vivo validation
    Wiley ; 2011
    In:  Journal of Magnetic Resonance Imaging Vol. 33, No. 6 ( 2011-06), p. 1351-1361
    Details
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 33, No. 6 ( 2011-06), p. 1351-1361
    Abstract: To develop a novel MR‐based method for visualizing the elastic properties of human lung parenchyma in vivo and to evaluate the ability of this method to resolve differences in parenchymal stiffness at different respiration states in healthy volunteers. Materials and Methods: A spin‐echo MR Elastography (MRE) pulse sequence was developed to provide both high shear wave motion sensitivity and short TE for improved visualization of lung parenchyma. The improved motion sensitivity of this approach was modeled and tested with phantom experiments. In vivo testing was then performed on 10 healthy volunteers at the respiratory states of residual volume (RV) and total lung capacity (TLC). Results: Shear wave propagation was visualized within the lungs of all volunteers and was processed to provide parenchymal shear stiffness maps for all 10 subjects. Density corrected stiffness values at TLC (1.83 ± 0.22 kPa) were higher than those at the RV (1.14 ± 0.14 kPa) with the difference being statistically significant ( P 〈 0.0001). Conclusion: 1 H‐based MR elastography can noninvasively measure the shear stiffness of human lung parenchyma in vivo and can quantitate the change in shear stiffness due to respiration. The values obtained were consistent with previously reported in vitro assessments of cadaver lungs. Further work is required to increase the flexibility of the current acquisition and to investigate the clinical potential of lung MRE. J. Magn. Reson. Imaging 2011;33:1351–1361. © 2011 Wiley‐Liss, Inc.
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    URL: Article
    DOI: 10.1002/jmri.v33.6
    DOI: 10.1002/jmri.22550
    Language: English
    Publisher: Wiley
    Publication Date: 2011
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