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3D MRI of impaired hyperpolarized 129 Xe uptake in a rat model of pulmonary fibrosis
Author(s) -
Cleveland Zackary I.,
Virgincar Rohan S.,
Qi Yi,
Robertson Scott H.,
Degan Simone,
Driehuys Bastiaan
Publication year - 2014
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3127
Subject(s) - pulmonary fibrosis , nuclear magnetic resonance , fibrosis , nuclear medicine , chemistry , physics , medicine , radiochemistry , pathology
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 2 and O 2 ) cannot be detected directly within the lungs. Hyperpolarized (HP) 129 Xe is a promising surrogate for these metabolic gases, because MR spectroscopy and imaging allow gaseous alveolar 129 Xe to be detected separately from 129 Xe dissolved in the red blood cells (RBCs) and the adjacent tissues, which comprise blood plasma and lung interstitium. Because 129 Xe reaches the RBCs by diffusing across the same barrier tissues (blood plasma and interstitium) as O 2 , barrier thickening will delay 129 Xe transit and, thus, reduce RBC‐specific 129 Xe MR signal. Here we have exploited these properties to generate 3D, MR images of 129 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 129 Xe by the RBCs, quantified as the fraction of RBC signal relative to total dissolved 129 Xe signal, was significantly reduced ( P = 0.03) in the injured lungs of bleomycin‐treated animals. In contrast, no significant difference ( P = 0.56) was observed between the saline‐treated and untreated lungs of control animals. Together, these results indicate that 3D MRI of HP 129 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.