Quantitative functional lung imaging with synchrotron radiation using inhaled xenon as contrast agent

Area of Science:

• Medical Imaging
• Pulmonary Medicine
• Radiography

Background:

• Small airways are crucial for lung ventilation-perfusion matching.
• Accurate assessment of small airway function is challenging with current imaging techniques.

Purpose of the Study:

• To introduce and evaluate K-edge subtraction (KES) radiography with stable xenon (Xe) gas for imaging small airways and regional lung ventilation.
• To assess the functional capacity of airways with diameters as small as 1 mm.

Main Methods:

• Experiments were conducted using monochromatic synchrotron radiation beams at the European Synchrotron Radiation Facility.
• Quantitative, respiration-gated KES radiography was performed on two anesthetized rabbits inhaling stable Xe gas.
• Simultaneous imaging at two energy levels allowed for absolute Xe concentration calculations and visualization of Xe distribution dynamics.

Main Results:

• KES radiography successfully visualized bronchi down to 1 mm in diameter in both planar and CT images.
• Absolute Xe concentrations were calculated in airways and lung tissue.
• Local time constants of ventilation were determined by analyzing sequential CT images, demonstrating Xe gas dynamics.

Conclusions:

• KES imaging with Xe gas is a promising technique for studying ventilation distribution in the lungs.
• This method enables the evaluation of small airway function, offering new insights into respiratory diseases.