title: Magnetic susceptibility matching at the air-tissue interface in rat lung by using a superparamagnetic intravascular contrast agent: influence on transverse relaxation time of hyperpolarized helium-3.
abstract: Transverse relaxation of hyperpolarized helium-3 magnetization in respiratory airways highly depends on local magnetic field gradients induced by the magnetic susceptibility difference between gas and pulmonary tissue. Fast transverse relaxation is known to be an important feature that yields information about lung microstructure and function, but it is also an essential limitation in designing efficient strategies for lung imaging. Using intravascular injections of a superparamagnetic contrast agent in rats, it was possible to increase the overall susceptibility of the perfused lung tissues and hence to match it with the gas susceptibility. The transverse decay time constant of inhaled hyperpolarized helium-3 was measured in multiple-spin-echo experiments at 1.5 T as a function of the superparamagnetic contrast agent concentration in the animal blood. The time constant was increased by a factor of 3 when an optimal concentration was reached as predicted for susceptibility matching by combining intrinsic susceptibilities of tissue, blood, and gas.
authors.affiliation: U2R2M CNRS UMR8081, Université Paris-Sud, CIERM, Hôpital de Bicêtre, Le Kremlin-Bicêtre cedex, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vignaud
authors.forename: Xavier
authors.initials: X
authors.lastname: Maître
authors.forename: Geneviève
authors.initials: G
authors.lastname: Guillot
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Durand
authors.forename: Ludovic
authors.initials: L
authors.lastname: de Rochefort
authors.forename: Philippe
authors.initials: P
authors.lastname: Robert
authors.forename: Véronique
authors.initials: V
authors.lastname: Vivès
authors.forename: Robin
authors.initials: R
authors.lastname: Santus
authors.forename: Luc
authors.initials: L
authors.lastname: Darrasse
mesh_terms: D000280:Administration, Inhalation; D000388:Air; D000465:Algorithms; D000818:Animals; D003287:Contrast Media; D003911:Dextrans; D004305:Dose-Response Relationship, Drug; D052203:Ferrosoferric Oxide; D006371:Helium / Q000008:administration & dosage; D007089:Image Enhancement / Q000379:methods; D007275:Injections, Intravenous; D007501:Iron / Q000008:administration & dosage; D007554:Isotopes / Q000008:administration & dosage; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D010087:Oxides / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013499:Surface Properties
chemical_list: D003287:Contrast Media; D003911:Dextrans; D007554:Isotopes; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D006371:Helium; D007501:Iron; D052203:Ferrosoferric Oxide