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Updated: Jun 3, 2026
Acquiring Hyperpolarized 129Xe Magnetic Resonance Images of Lung Ventilation
Published on: November 21, 2023
Hyperpolarized 129Xe MR imaging with balanced steady-state free precession in spontaneously breathing mouse lungs
Fumito Imai1, Ryosuke Kashiwagi, Hirohiko Imai
1Division of Medical Physics and Engineering, Area of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Osaka University, Suita, Japan. kk_nest_003_fi@yahoo.co.jp
Purpose:
We investigated the characteristics of hyperpolarized (HP) (129)Xe magnetic resonance (MR) imaging obtained from balanced steady-state free precession (SSFP) measurement of mouse lungs, especially under spontaneous breathing, and compared the results with those obtained using traditional spoiled gradient echo (SPGR) method, focusing on improved signal-to-noise ratio (SNR) and reduced total acquisition time.
Methods:
We calculated magnetization response of the HP (129)Xe gas for the balanced SSFP sequence under spontaneous breathing to derive optimal conditions for the imaging experiment. We then placed an anesthetized mouse in the magnet (9.4T) supplied with oxygen gas and a mixture of HP (129)Xe gas supplied from a continuous-flow hyperpolarizing system. We obtained an axial plane image of the lung through balanced SSFP and SPGR sequences, changing the various magnetic resonance (MR) imaging parameters, and measured the SNR of these images.
Results:
We demonstrated the clear dependence of image intensity on flip angle and number of shots. The SNR was higher in balanced SSFP than in SPGR and 2.3-fold higher compared at each maximum. In contrast, total acquisition time in balanced SSFP was shortened to about one-eighth that of SPGR using a one-shot acquisition mode.
Conclusion:
In HP (129)Xe MR imaging of the lung of a spontaneously breathing mouse, balanced SSFP sequence with multi-shot and centric order acquisition provides higher SNR in a shorter acquisition time than SPGR.
Insights
Hyperpolarized (129)Xenon (Xe) magnetic resonance (MR) imaging using balanced steady-state free precession (SSFP) significantly improves signal-to-noise ratio (SNR) and reduces acquisition time in mouse lungs compared to traditional spoiled gradient echo (SPGR) methods.
Area of Science:
- Medical Imaging
- Pulmonary Medicine
- Biophysics
Background:
- Hyperpolarized (129)Xenon ((129)Xe) magnetic resonance (MR) imaging offers unique insights into lung function.
- Traditional spoiled gradient echo (SPGR) sequences can be time-consuming and may have suboptimal signal-to-noise ratio (SNR).
- Optimizing imaging sequences is crucial for efficient and effective pulmonary imaging.
Purpose of the Study:
- To investigate the characteristics of balanced steady-state free precession ((SSFP)) sequences for hyperpolarized (HP) (129)Xe MR imaging of mouse lungs.
- To compare the performance of SSFP with traditional SPGR methods, focusing on SNR and acquisition time.
- To evaluate SSFP under spontaneous breathing conditions.
Main Methods:
- Magnetization response of HP (129)Xe for SSFP sequences under spontaneous breathing was calculated to determine optimal experimental conditions.
- Anesthetized mice were imaged using both SSFP and SPGR sequences at 9.4T, with varying MR imaging parameters.
- Signal-to-noise ratio (SNR) was measured for images acquired using both sequences.
Main Results:
- Image intensity showed clear dependence on flip angle and number of shots.
- Balanced SSFP achieved a 2.3-fold higher maximum SNR compared to SPGR.
- Total acquisition time was reduced to approximately one-eighth with SSFP using a one-shot acquisition mode.
Conclusions:
- Balanced SSFP sequences, particularly with multi-shot and centric order acquisition, provide superior SNR in shorter acquisition times for HP (129)Xe MR imaging of spontaneously breathing mouse lungs.
- This advancement offers a more efficient approach for pulmonary imaging compared to SPGR.
- The findings support the use of SSFP for improved lung imaging studies.
