Hyperpolarized xenon-129 phase-contrast velocimetry in an inhaler spacer and the upper airways using direction-specific aliasing velocities

Motivation: Understanding gas flow dynamics in the airways is crucial for developing inhaled therapies and treatment for airways diseases. Goal(s): To measure gas velocities within the upper airways and within an aerosol inhaler spacer. Approach: 3D phase contrast velocity MRI with hyperpolarized xenon-129 using the 4-point Hadamard interleave method with spiral readout was used. The aliasing velocity was set at different values for each direction to improve dynamic range matching to expected velocities. Results: Measurement of gas flow patterns in an inhaler spacer as well as in the upper airways in vivo was feasible. Impact: The results demonstrate the feasibility of phase-contrast velocimetry MRI of inhaled xenon-129 within an inhaler spacer and the upper airways. This will improve validation of computational fluid dynamics to improve inhaled therapy delivery and understanding of upper airways diseases.