Nuclear magnetic resonance imaging of airways in humans with use of hyperpolarized 3He

The nuclear spin polarization of noble gases can be enhanced strongly by laser optical pumping followed by electron-nuclear polarization transfer. Direct optical pumping of metastable ³He atoms has been shown to produce enormous polarization on the order of 0.4–0.6. This is about 10⁵ times larger than the polarization of water protons at thermal equilibrium used in conventional MRI. We demonstrate that hyper-polarized ³He gas can be applied to nuclear magnetic resonance imaging of organs with air-filled spaces in humans. In vivo ³He MR experiments were performed in a whole-body MR scanner with a superconducting magnet ramped down to 0.8 T. Anatomical details of the upper respiratory tract and of the lungs of a volunteer were visualized with the FLASH technique demonstrating the potential of the method for fast imaging of airways in the human body and for pulmonary ventilation studies.