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In vivo MR imaging and spectroscopy using hyperpolarized 129Xe
M E Wagshul1, T M Button, H F Li
1Department of Radiology, State University of New York at Stony Brook 11794-8460, USA.
Abstract:
Hyperpolarized 129Xe has been used to obtain gas phase images of mouse lung in vivo, showing distinct ventilation variation as a function of the breathing cycle. Spectra of 129Xe in the thorax show complex structure in both the gas phase (-4 to 3 ppm) and tissue-dissolved (190-205 ppm) regions. The alveolar gas peak shows correlated intensity and frequency oscillations, both attributable to changes in lung volume during breathing. The two major dissolved peaks near 195-200 ppm are attributed to lung parenchyma and to blood; they reach maximum intensity in 5-10 s and decay with an apparent T1 of 30 s. Another peak at 190 ppm takes 20-30 s to reach maximum; this must represent other well-vascularized tissue (e.g., heart and other muscles) in the thorax. The maximum integrated area of the tissue components reaches 30-80% of the maximum alveolar gas area, indicating that imaging at tissue frequencies can be achieved.
Insights
This study uses hyperpolarized 129Xe MRI to image mouse lungs, revealing ventilation variations during breathing. Dissolved 129Xe in lung tissue and blood allows for in vivo imaging of thoracic structures.
Area of Science:
- Medical Imaging
- Magnetic Resonance Imaging
- Pulmonary Medicine
Background:
- Hyperpolarized 129Xe MRI is a powerful tool for lung imaging.
- Understanding ventilation and gas exchange in the lungs is crucial for diagnosing respiratory diseases.
Purpose of the Study:
- To investigate the use of hyperpolarized 129Xe MRI for in vivo imaging of mouse lungs.
- To characterize the ventilation dynamics and dissolved 129Xe signals in lung tissue and blood.
Main Methods:
- Gas phase imaging of mouse lungs using hyperpolarized 129Xe.
- Acquisition and analysis of 129Xe spectra in both gas and tissue-dissolved phases.
- Monitoring signal intensity and frequency changes correlated with the breathing cycle.
Main Results:
- Distinct ventilation variations were observed throughout the breathing cycle.
- Complex spectral structures were identified in both gas (-4 to 3 ppm) and tissue-dissolved (190-205 ppm) regions.
- Dissolved 129Xe peaks attributed to lung parenchyma, blood, and other thoracic tissues showed distinct uptake and decay kinetics.
Conclusions:
- Hyperpolarized 129Xe MRI enables in vivo imaging of mouse lung ventilation and tissue composition.
- The study demonstrates the potential for imaging dissolved 129Xe in lung parenchyma, blood, and other thoracic tissues.
- This technique offers a novel approach for studying lung physiology and pathology in vivo.