An open-access, low-field MRI system for human lung imaging with hyperpolarized 3He

The human lung is exquisitely sensitive to gravity and posture. However, conventional high-field magnets used for hyperpolarized noble gas MRI of the human lung restrict subjects to lying horizontally. We have built an open-access, low-magnetic-field ($<$5 mT) MRI instrument which allows freedom of body positioning while providing high-resolution lung images. We have performed 3He lung MRI of human subjects in both the supine and upright positions; and used these images to make the first-ever maps of the heterogeneous distribution of oxygen in the human lung in an upright position.