3D MRI of impaired hyperpolarized 129Xe uptake in a rat model of pulmonary fibrosis. (12th May 2014)

• Record Type: Journal Article
• Authors: Cleveland, Zackary I.; Virgincar, Rohan S.; Qi, Yi; Robertson, Scott H.; Degan, Simone; Driehuys, Bastiaan; Rizi, Rahim R.
• Is Part Of: NMR in biomedicine. Volume 27:Number 12(2014:Dec.)
• Page Start: 1502
• Page End: 1514
• Publication Date: 2014-05-12
• Subjects: Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.3127
• Languages: English
• ISSNs: 0952-3480

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A variety of pulmonary pathologies, in particular interstitial lung diseases, are characterized by thickening of the pulmonary blood–gas barrier, and this thickening results in reduced gas exchange. Such diffusive impairment is challenging to quantify spatially, because the distributions of the metabolically relevant gases (CO<sub>2</sub> and O<sub>2</sub>) cannot be detected directly within the lungs. Hyperpolarized (HP) <sup>129</sup>Xe is a promising surrogate for these metabolic gases, because MR spectroscopy and imaging allow gaseous alveolar <sup>129</sup>Xe to be detected separately from <sup>129</sup>Xe dissolved in the red blood cells (RBCs) and the adjacent tissues, which comprise blood plasma and lung interstitium. Because <sup>129</sup>Xe reaches the RBCs by diffusing across the same barrier tissues (blood plasma and interstitium) as O<sub>2</sub>, barrier thickening will delay <sup>129</sup>Xe transit and, thus, reduce RBC‐specific <sup>129</sup>Xe MR signal. Here we have exploited these properties to generate 3D, MR images of <sup>129</sup>Xe uptake by the RBCs in two groups of rats. In the experimental group, unilateral fibrotic injury was generated prior to imaging by instilling bleomycin into one lung. In the control group, a unilateral sham instillation of saline was performed. Uptake of <sup>129</sup>Xe by the RBCs, quantified as the fraction of RBC signal relative to total dissolved <sup>129</sup>Xe signal, was significantly reduced (<italic>P</italic> = 0.03) in the injured lungs of bleomycin‐treated animals. In contrast, no significant difference (<italic>P</italic> = 0.56) was observed between the saline‐treated and untreated lungs of control animals. Together, these results indicate that 3D MRI of HP <sup>129</sup>Xe dissolved in the pulmonary tissues can provide useful biomarkers of impaired diffusive gas exchange resulting from fibrotic thickening. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>