title: Rapid imaging of hyperpolarized gas using EPI.
abstract: Rapid repetitive MRI of hyperpolarized (HP) gases using echo-planar imaging (EPI) has been theoretically investigated and experimentally demonstrated for (3)He in human lung. A quantitative treatment of signal attenuation and magnetization consumption for the unique circumstance of a rapidly diffusing nonrenewable magnetization source has been performed. Rapid (compared to the human respiratory cycle) and repetitive imaging of the lung gas space with EPI and a single delivered bolus of HP-(3)He is feasible using low flip angles, provided the voxels are not too small. A coarse-grid (32 x 64) EPI pulse sequence has been developed and implemented to image the lungs of healthy volunteers during rebreathing of a HP-(3)He/N(2) gas mixture. A set of three 10-mm axial slices was imaged every 0.12 sec for the 36 sec duration of rebreathing, yielding a real-time visualization of ventilation. Despite some mild artifacts, the images are of good quality and show changes in gas density related to respiratory physiology. Magn Reson Med 42:507-514, 1999.
authors.affiliation: Department of Physics, Washington University, St. Louis, Missouri, USA.
authors.forename: B
authors.initials: B
authors.lastname: Saam
authors.forename: D A
authors.initials: DA
authors.lastname: Yablonskiy
authors.forename: D S
authors.initials: DS
authors.lastname: Gierada
authors.forename: M S
authors.initials: MS
authors.lastname: Conradi
mesh_terms: D017352:Echo-Planar Imaging / Q000379:methods*; D006371:Helium; D006801:Humans; D008168:Lung / Q000502:physiology*; D008433:Mathematics; D012119:Respiration
chemical_list: D006371:Helium