Direct Measurement of Lung Motion Using Hyperpolarized Helium-3 MR Tagging

Purpose: To measure lung motion between end-inhalation and end-exhalation using a hyperpolarized helium-3 (HP3He) magnetic resonance (MR) tagging technique. Methods and Materials: Three healthy volunteers underwent MR tagging studies after inhalation of 1 L HP3He gas diluted with nitrogen. Multiple-slice two-dimensional and volumetric three-dimensional MR tagged images of the lungs were obtained at end-inhalation and end-exhalation, and displacement vector maps were computed. Results: The grids of tag lines in the HP3He MR images were well defined at end-inhalation and remained evident at end-exhalation. Displacement vector maps clearly demonstrated the regional lung motion and deformation that occurred during exhalation. Discontinuity and differences in motion pattern between two adjacent lung lobes were readily resolved. Conclusions: Hyperpolarized helium-3 MR tagging technique can be used for direct in vivo measurement of respiratory lung motion on a regional basis. This technique may lend new insights into the regional pulmonary biomechanics and thus provide valuable information for the deformable registration of lung.