Physiological gas exchange mapping of hyperpolarized 129 Xe using spiral-IDEAL and MOXE in a model of regional radiation-induced lung injury.

Abstract

PURPOSE:

To map physiological gas exchange parameters using dissolved hyperpolarized (HP) 129 Xe in a rat model of regional radiation-induced lung injury (RILI) with spiral-IDEAL and the model of xenon exchange (MOXE). Results are compared to quantitative histology of pulmonary tissue and red blood cell (RBC) distribution.

METHODS:

Two cohorts (n = 6 each) of age-matched rats were used. One was irradiated in the right-medial lung, producing regional injury. Gas exchange was mapped 4 weeks postirradiation by imaging dissolved-phase HP 129 Xe using spiral-IDEAL at five gas exchange timepoints using a clinical 1.5 T scanner. Physiological lung parameters were extracted regionally on a voxel-wise basis using MOXE. Mean gas exchange parameters, specifically air-capillary barrier thickness (δ) and hematocrit (HCT) in the right-medial lung were compared to the contralateral lung as well as nonirradiated control animals. Whole-lung spectroscopic analysis of gas exchange was also performed.

RESULTS:

δ was significantly increased (1.43 ± 0.12 μm from 1.07 ± 0.09 μm) and HCT was significantly decreased (17.2 ± 1.2% from 23.6 ± 1.9%) in the right-medial lung (i.e., irradiated region) compared to the contralateral lung of the irradiated rats. These changes were not observed in healthy controls. δ and HCT correlated with histologically measured increases in pulmonary tissue heterogeneity (r = 0.77) and decreases in RBC distribution (r = 0.91), respectively. No changes were observed using whole-lung analysis.

CONCLUSION:

This work demonstrates the feasibility of mapping gas exchange using HP 129 Xe in an animal model of RILI 4 weeks postirradiation. Spatially resolved gas exchange mapping is sensitive to regional injury between cohorts that was undetected with whole-lung gas exchange analysis, in agreement with histology. Gas exchange mapping holds promise for assessing regional lung function in RILI and other pulmonary diseases.

• Authors: Brandon Zanette, Elaine Stirrat, Salomeh Jelveh, Andrew Hope, Giles Santyr
• Journal: Medical physics (Med Phys) Vol. 45 Issue 2 Pg. 803-816 (Feb 2018) ISSN: 2473-4209 [Electronic] United States
• PMID: 29238999 (Publication Type: Journal Article)
• Copyright: © 2017 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Chemical References

• Xenon Isotopes
• Xenon-129

Topics

• Animals
• Lung (diagnostic imaging, metabolism, radiation effects)
• Magnetic Resonance Imaging
• Male
• Rats
• Rats, Sprague-Dawley
• Xenon Isotopes (adverse effects, metabolism)