title: In vitro validation of computational fluid dynamic simulation in human proximal airways with hyperpolarized 3He magnetic resonance phase-contrast velocimetry.
abstract: Computational fluid dynamics (CFD) and magnetic resonance (MR) gas velocimetry were concurrently performed to study airflow in the same model of human proximal airways. Realistic in vivo-based human airway geometry was segmented from thoracic computed tomography. The three-dimensional numerical description of the airways was used for both generation of a physical airway model using rapid prototyping and mesh generation for CFD simulations. Steady laminar inspiratory experiments (Reynolds number Re = 770) were performed and velocity maps down to the fourth airway generation were extracted from a new velocity mapping technique based on MR velocimetry using hyperpolarized (3)He gas. Full two-dimensional maps of the velocity vector were measured within a few seconds. Numerical simulations were carried out with the experimental flow conditions, and the two sets of data were compared between the two modalities. Flow distributions agreed within 3%. Main and secondary flow velocity intensities were similar, as were velocity convective patterns. This work demonstrates that experimental and numerical gas velocity data can be obtained and compared in the same complex airway geometry. Experiments validated the simulation platform that integrates patient-specific airway reconstruction process from in vivo thoracic scans and velocity field calculation with CFD, hence allowing the results of this numerical tool to be used with confidence in potential clinical applications for lung characterization. Finally, this combined numerical and experimental approach of flow assessment in realistic in vivo-based human airway geometries confirmed the strong dependence of airway flow patterns on local and global geometrical factors, which could contribute to gas mixing.
authors.affiliation: U2R2M, Unité de Recherche en Résonance Magnétique Médicale, CNRS, Univ Paris-Sud, Le Kremlin-Bicêtre, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: de Rochefort
authors.forename: Laurence
authors.initials: L
authors.lastname: Vial
authors.forename: Redouane
authors.initials: R
authors.lastname: Fodil
authors.forename: Xavier
authors.initials: X
authors.lastname: Maître
authors.forename: Bruno
authors.initials: B
authors.lastname: Louis
authors.forename: Daniel
authors.initials: D
authors.lastname: Isabey
authors.forename: Georges
authors.initials: G
authors.lastname: Caillibotte
authors.forename: Marc
authors.initials: M
authors.lastname: Thiriet
authors.forename: Jacques
authors.initials: J
authors.lastname: Bittoun
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Durand
authors.forename: Gabriela
authors.initials: G
authors.lastname: Sbirlea-Apiou
mesh_terms: D001980:Bronchi / Q000033:anatomy & histology / Q000502:physiology*; D001995:Bronchography; D003198:Computer Simulation; D006371:Helium; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007554:Isotopes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008954:Models, Biological; D015203:Reproducibility of Results; D012119:Respiration; D015656:Respiratory Mechanics; D012212:Rheology; D014057:Tomography, X-Ray Computed; D014132:Trachea / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*
chemical_list: D007554:Isotopes; D006371:Helium