Impact of inflation level on breath-hold 1H MRI surrogates of regional lung ventilation.

Motivation: While breath-hold 1H-MRI ventilation surrogates require imaging at different inflation levels, the impact of inflation level selection on derived measurements remains unclear. Goal(s): To evaluate the relationship between ventilation surrogates derived from different combinations of lung inflation levels (TLC, FRC+1L, RV) in healthy volunteers and patients with asthma and COVID-19 pneumonia. Approach: Forty-seven subjects underwent breath-hold 1H-MRI at the aforementioned inflation levels. Ventilation surrogates were derived using deformable registration between paired inflation states and specific ventilation calculation. Results: Strong correlation was observed between TLC-RV and FRC-RV surrogates (r=0.87), while other combinations showed markedly lower agreement (r=0.23-0.51). Impact: This study demonstrates that breath-hold 1H-MRI ventilation surrogates vary significantly with inflation level. The strong agreement between measures derived from TLC-RV and FRC-RV suggests these combinations provide similar information, while other pairs may capture complementary aspects of regional ventilation distribution.