Direct visualisation of collateral ventilation in COPD with hyperpolarised gas MRI

Area of Science:

• Pulmonary Medicine
• Medical Imaging
• Respiratory Physiology

Background:

• Collateral ventilation is a proposed compensatory mechanism in obstructive lung diseases, but in vivo observations are scarce.
• Imaging collateral ventilation can enhance understanding of lung physiology and guide emphysema treatments.
• Current methods for assessing collateral ventilation are limited.

Purpose of the Study:

• To image delayed ventilation, potentially reflecting collateral ventilation, during a single breath-hold in chronic obstructive pulmonary disease (COPD) patients.
• To develop and validate a non-invasive imaging technique for assessing regional lung ventilation.
• To visualize the dynamic process of gas exchange in diseased lungs.

Main Methods:

• Time-resolved, breath-hold, hyperpolarized helium-3 (He-3) magnetic resonance imaging (MRI).
• Imaging the progressive influx of polarized He-3 gas into initially non-ventilated lung regions.
• Utilizing a single breath-hold technique for dynamic imaging.

Main Results:

• A time-series of images revealed He-3 gas moving into previously unventilated lung areas.
• Delayed filling of ventilation defects was observed in 8 out of 10 scanned COPD patients.
• The imaging technique provided 3D, whole-lung coverage with regional sensitivity.

Conclusions:

• A method for directly imaging delayed ventilation within a single breath-hold in COPD patients was successfully demonstrated.
• The study presents images believed to represent collateral ventilation and slow airspace filling due to airflow resistance.
• This non-invasive, non-ionizing MRI technique offers valuable insights into lung ventilation dynamics.