Optically polarized helium-3 for NMR imaging in medicine

Recent investigations in magnetic resonance imaging in animals and human su bjects have demonstrated that laser polarized helium-3 can be used to visua lize airways and air spaces. This report presents the current performances and possible improvements of optical pumping techniques for the production of polarized gas. The specific properties and dynamics of the polarization inside the lungs am also discussed. They impact both the development of opt imal imaging methods and the analysis of the data to extract physiological information. Applications to medical assessment of lung ventilation and fun ction are considered.