Quantitative Measure of Lung Structure and Function Obtained from Hyperpolarized Xenon Spectroscopy.

Area of Science:

• Pulmonary Medicine
• Medical Imaging
• Biophysics

Background:

• Hyperpolarized Xenon-129 (HXe) MRI offers detailed lung ventilation and diffusion mapping.
• Advanced techniques are needed to assess gas exchange dynamics at high temporal resolution.

Purpose of the Study:

• To describe and validate the chemical shift saturation recovery (CSSR) MR spectroscopy technique.
• To demonstrate its application in assessing lung physiological parameters on a millisecond timescale.

Main Methods:

• Utilized HXe-MRI with CSSR MR spectroscopy.
• Employed single-dose breath-hold and multi-dose free-breathing protocols.
• Applied calibrated radiofrequency pulses and analyzed signal recovery over variable delay times using a 1D gas-exchange model.

Main Results:

• CSSR MR spectroscopy successfully traced pulmonary Xenon gas exchange on a millisecond timescale.
• The technique allowed for the assessment of capillary blood volume, septal wall thickness, and alveolar surface-to-volume ratio.
• Analysis of spectra and fitting to a gas-exchange model yielded quantitative physiological parameters.

Conclusions:

• CSSR MR spectroscopy is a powerful tool for dynamic lung function assessment.
• This technique provides novel insights into gas exchange kinetics and alveolar structure.
• HXe-MRI combined with CSSR spectroscopy advances the non-invasive evaluation of lung physiology.