Quantifying Regional Radiation-Induced Lung Injury in Patients Using Hyperpolarized ¹²⁹Xe Gas Exchange Magnetic...

Area of Science:

• Pulmonary imaging and radiation oncology.
• Quantitative assessment of lung function post-treatment.

Background:

• Radiation-induced lung injury (RILI) affects regional lung ventilation and perfusion.
• Regional pulmonary gas exchange changes in RILI have not been previously quantified.

Purpose of the Study:

• To measure and quantify regional, dose-dependent changes in pulmonary gas exchange following radiation therapy (RT) for lung cancer.
• To assess the utility of hyperpolarized 129Xe MRI in mapping lung function after RT.

Main Methods:

• Ten lung cancer patients underwent pre-RT and 3-month post-RT 129Xe MRI to map gas exchange in airspaces, alveolar membrane, and pulmonary capillaries.
• Deformable registration transferred 129Xe functional maps to RT planning CT scans.
• Dose-dependent changes in ventilation, membrane uptake, and RBC transfer were calculated and correlated with RT dose.

Main Results:

• Post-RT, ventilation decreased (-0.24%/Gy), membrane uptake increased (0.69%/Gy), and RBC transfer decreased (-0.41%/Gy) with dose.
• Increased membrane uptake correlated with RT dose at 8 months post-RT (0.73%/Gy).
• Changes were more pronounced in patients with less heterogeneous baseline lung function.

Conclusions:

• Hyperpolarized 129Xe MRI effectively quantifies regional, dose-dependent changes in pulmonary gas exchange after RT.
• This imaging technique offers a potential tool for improving the understanding and management of RILI.