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Updated: May 19, 2026
Acquiring Hyperpolarized 129Xe Magnetic Resonance Images of Lung Ventilation
Published on: November 21, 2023
Direct imaging of hyperpolarized 129Xe alveolar gas uptake in a mouse model of emphysema
Satoshi Iguchi1, Hirohiko Imai, Yuki Hori
1Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Abstract:
MRI of hyperpolarized (129)Xe dissolved in pulmonary tissues, and blood has the potential to offer a new tool for regional evaluation of pulmonary gas exchange and perfusion; however, the extremely short T2* and low magnetization density make it difficult to acquire the image. In this study, an ultrashort echo-time sequence was introduced, and its feasibility to quantitatively assess emphysema-like pulmonary tissue destruction by a combination of dissolved- and gas-phase (129)Xe lung MRI was investigated. The ultrashort echo-time has made it possible to acquire dissolved (129)Xe images with reasonably high spatial resolution of 0.625 × 0.625 mm(2) and to obtain T2* of 0.67 ± 0.30 ms in a spontaneously breathing mouse at 9.4 T. The regional dynamic alveolar gas uptake as well as subsequent transport by pulmonary blood flow was also visualized. The ratio of (129)Xe magnetization that diffused into the septa relative to the gas-phase magnetization F was regionally evaluated. The mean F value of elastase-treated mice was 2.28 ± 0.46%, which was significantly reduced from that of control mice 3.41 ± 0.48% (P = 0.0052). This reflects the reduced uptake efficiency due to alveolar tissue destruction and is correlated with the histologically derived alveolar surface-to-volume ratio.
Insights
This study introduces ultrashort echo-time MRI to assess lung tissue damage. Hyperpolarized (129)Xe MRI quantifies gas exchange in emphysema, revealing reduced uptake efficiency due to alveolar destruction.
Area of Science:
- Pulmonary Medicine
- Medical Imaging
- Biophysics
Background:
- Hyperpolarized (129)Xe MRI offers potential for evaluating regional pulmonary gas exchange and perfusion.
- Challenges include short T2* and low magnetization density, hindering image acquisition.
- Emphysema involves pulmonary tissue destruction, impacting gas exchange efficiency.
Purpose of the Study:
- To investigate the feasibility of using ultrashort echo-time (USET) MRI with dissolved- and gas-phase (129)Xe.
- To quantitatively assess emphysema-like pulmonary tissue destruction.
- To evaluate regional gas uptake and blood transport in the lungs.
Main Methods:
- Introduction of an ultrashort echo-time (USET) sequence for (129)Xe MRI.
- Acquisition of dissolved (129)Xe images with high spatial resolution (0.625 × 0.625 mm²).
- Measurement of T2* in spontaneously breathing mice at 9.4 T.
- Regional evaluation of the ratio of (129)Xe magnetization diffused into septa to gas-phase magnetization (F).
Main Results:
- USET MRI enabled acquisition of dissolved (129)Xe images with T2* of 0.67 ± 0.30 ms.
- Regional dynamic alveolar gas uptake and pulmonary blood flow were visualized.
- Elastase-treated mice showed a significantly reduced mean F value (2.28 ± 0.46%) compared to controls (3.41 ± 0.48%).
Conclusions:
- USET (129)Xe MRI is feasible for quantitative assessment of emphysema-like lung tissue destruction.
- The reduced F value in treated mice reflects impaired gas uptake due to alveolar damage.
- Findings correlate with histological measures of alveolar surface-to-volume ratio.
