Magnetic resonance assessment of parenchymal elasticity in normal and edematous, ventilator-injured lung

Kiaran P. McGee, Yogesh K. Mariappan, Rolf D. Hubmayr, Rickey E. Carter, Zhonghao Bao, David L. Levin, Armando Manduca, Richard L. Ehman

Research output: Contribution to journalArticle

17 Scopus citations

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 fluidfilled lung at transpulmonary pressures (Ptp) up to 25 cm H2O. Pulmonary edema was induced in anesthetized female adult Sprague-Dawley rats by mechanical ventilation to a pressure of 40 cm H2O for ∼30 min. Prior to imaging the wet weight of each ex vivo lung set was measured. MRE, high-resolution T1-weighted spin echo and T2* gradient echo data were acquired at each Ptp for both normal and injured ex vivo lungs. At Ptps of 6 cm H2O and greater, the shear stiffness of normal lungs was greater than injured lungs (P ≤ 0.0003). For Ptps up to 12 cm H2O, 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 H2O, respectively. For injured lungs MRE magnitude signal and shear stiffness within regions of differing degrees of alveolar flooding were calculated as a function of Ptp. 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.

Original languageEnglish (US)
Pages (from-to)666-676
Number of pages11
JournalJournal of applied physiology
Volume113
Issue number4
DOIs
StatePublished - Aug 15 2012

Keywords

  • Compliance
  • Edema
  • Lung elasticity
  • Magnetic resonance elastography
  • Magnetic resonance imaging
  • Shear modulus
  • Surface tension
  • Surfactant

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Fingerprint Dive into the research topics of 'Magnetic resonance assessment of parenchymal elasticity in normal and edematous, ventilator-injured lung'. Together they form a unique fingerprint.

  • Cite this