After obtaining informed consent, subjects are trained in a breath holding technique that permits obtaining reproducible proton and hyperpolarized helium (HHE) lung images. 3-Helium is obtained from a vendor and hyperpolarized using an optical spin transfer device (FDA Investigational New Drug (IND) 122,670) and administered through a valved inhalation device while in the MRI scanner. Images are obtained during an \~15 second inspiratory breath hold. Proton MRI images are similarly obtained during a breath hold with room air using an ultrashort echo time sequence. From these MRI images, lung volumes, alveolar sizes, and estimated alveolar numbers are derived. Subjects are reimaged at 1 year to evaluate changes in these parameters during normal lung growth (controls) or after PSF (AIS subjects).
