title: Phase-contrast velocimetry with hyperpolarized 3He for in vitro and in vivo characterization of airflow.
abstract: This paper describes a technique that combines radial MRI and phase contrast (PC) to map the velocities of hyperpolarized gases ((3)He) in respiratory airways. The method was evaluated on well known geometries (straight and U-shaped pipes) before it was applied in vivo. Dynamic 2D maps of the three velocity components were obtained from a 10-mm slice with an in-plane spatial resolution of 1.6 mm within 1 s. Integration of the in vitro through-plane velocity over the slice matched the input flow within a relative precision of 6.4%. As expected for the given Reynolds number, a parabolic velocity profile was obtained in the straight pipe. In the U-shaped pipe the three velocity components were measured and compared to a fluid-dynamics simulation so the precision was evaluated as fine as 0.025 m s(-1). The technique also demonstrated its ability to visualize vortices and localize characteristic points, such as the maximum velocity and vortex-center positions. Finally, in vivo feasibility was demonstrated in the human trachea during inhalation.
authors.affiliation: U2R2M, Unité de Recherche en Résonance Magnétique Médicale, UMR 8081, CNRS-Université Paris-Sud, Le Kremlin-Bicêtre, France. Ludovic.De-Rochefort@cierm.u-psud.fr
authors.forename: Ludovic
authors.initials: L
authors.lastname: de Rochefort
authors.forename: Xavier
authors.initials: X
authors.lastname: Maître
authors.forename: Redouane
authors.initials: R
authors.lastname: Fodil
authors.forename: Laurence
authors.initials: L
authors.lastname: Vial
authors.forename: Bruno
authors.initials: B
authors.lastname: Louis
authors.forename: Daniel
authors.initials: D
authors.lastname: Isabey
authors.forename: Céline
authors.initials: C
authors.lastname: Croce
authors.forename: Luc
authors.initials: L
authors.lastname: Darrasse
authors.forename: Gabriela
authors.initials: G
authors.lastname: Apiou
authors.forename: Georges
authors.initials: G
authors.lastname: Caillibotte
authors.forename: Jacques
authors.initials: J
authors.lastname: Bittoun
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Durand
mesh_terms: D003287:Contrast Media; D006371:Helium / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007554:Isotopes / Q000008:administration & dosage; D008168:Lung / Q000033:anatomy & histology / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D012123:Pulmonary Ventilation / Q000502:physiology*; D012212:Rheology / Q000295:instrumentation / Q000379:methods*
chemical_list: D003287:Contrast Media; D007554:Isotopes; D006371:Helium