title: T2-shortening of 3He gas by magnetic microspheres.
abstract: In a gas-filled material like the lung parenchyma, the transverse relaxation time (T2) for 3He is shortened by the deposition of magnetic microspheres and rapid molecular diffusion through induced field distortions. Here, this unique relaxation process is described theoretically and predicted T2-shortening is validated using pressurized 3He gas in a foam model of alveolar airways. Results demonstrate that: (1) significant T2-shortening is induced by microsphere deposition, (2) shortened 3He T2s are accurately predicted, and (3) measured relaxation times are exploitable for quantifying local deposition patterns. Based on these findings the feasibility of imaging inhaled particulates in vivo with hyperpolarized 3He is examined and performance projections are formulated.
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA. kevin.minard@pnl.gov
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Minard
authors.forename: Charles
authors.initials: C
authors.lastname: Timchalk
authors.forename: Richard A
authors.initials: RA
authors.lastname: Corley
mesh_terms: D000818:Animals; D006371:Helium / Q000737:chemistry*; D006801:Humans; D008168:Lung; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008863:Microspheres; D019047:Phantoms, Imaging
chemical_list: D006371:Helium