title: Long-range diffusion of hyperpolarized 3He in explanted normal and emphysematous human lungs via magnetization tagging.
abstract: Long-range diffusivity of hyperpolarized 3He gas was measured from the decay rate of sinusoidally modulated longitudinal nuclear magnetization in three normal donor and nine severely emphysematous explanted human lungs. This (long-range) diffusivity, which we call Dsec, is measured over seconds and centimeters and is approximately 10 times smaller in healthy lungs (0.022 cm2/s) than the more traditionally measured Dmsec, which is measured over milliseconds and submillimeters. The increased restriction of Dsec reflects the complex, tortuous paths required to navigate long distances through the maze of branching peripheral airways. In emphysematous lungs, Dsec is substantially increased, with some regions showing nearly the unrestricted value of the self-diffusion coefficient (0.88 cm2/s for dilute 3He in air, a 40-fold increase). This suggests the presence of large collateral pathways opened by alveolar destruction that bypass the airways proper. This destruction was confirmed by comparison with histology in seven lungs and by removal of trapped gas via holes in the pleural surface in five lungs.
authors: Department of Physics, Box 1105, Washington University, One Brookings Dr., St. Louis, MO 63130-4899, USA. woods@wuphys.wustl.edu
authors: Jason C
authors: JC
authors: Woods
authors: Dmitriy A
authors: DA
authors: Yablonskiy
authors: Cliff K
authors: CK
authors: Choong
authors: Kimiaki
authors: K
authors: Chino
authors: John A
authors: JA
authors: Pierce
authors: James C
authors: JC
authors: Hogg
authors: John
authors: J
authors: Bentley
authors: Joel D
authors: JD
authors: Cooper
authors: Mark S
authors: MS
authors: Conradi
authors: Peter T
authors: PT
authors: Macklem
mesh_terms: D004646:Emphysema / Q000473:pathology* / Q000601:surgery; D006371:Helium; D006801:Humans; D066298:In Vitro Techniques; D007554:Isotopes; D016040:Lung Transplantation; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009584:Nitrogen; D011650:Pulmonary Alveoli / Q000473:pathology
chemical_list: D007554:Isotopes; D006371:Helium; D009584:Nitrogen