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

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 He-3 atoms has been shown to produce enormous polarization on the order of 0.4-0.6. This is about 10(5) times larger than the polarization of water protons at thermal equilibrium used in conventional MRI. We demonstrate that hyperpolarized He-3 gas can be applied to nuclear magnetic resonance imaging of organs with air-filled spaces in humans. In vivo He-3 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.