title: Dynamically scaled phantom phase contrast MRI compared to true-scale computational modeling of coronary artery flow.
abstract: To examine the feasibility of combining computational fluid dynamics (CFD) and dynamically scaled phantom phase-contrast magnetic resonance imaging (PC-MRI) for coronary flow assessment.
  
  
  
  Left main coronary bifurcations segmented from computed tomography with bifurcation angles of 33°, 68°, and 117° were scaled-up ∼7× and 3D printed. Steady coronary flow was reproduced in these phantoms using the principle of dynamic similarity to preserve the true-scale Reynolds number, using blood analog fluid and a pump circuit in a 3T MRI scanner. After PC-MRI acquisition, the data were segmented and coregistered to CFD simulations of identical, but true-scale geometries. Velocities at the inlet region were extracted from the PC-MRI to define the CFD inlet boundary condition.
  
  
  
  The PC-MRI and CFD flow data agreed well, and comparison showed: 1) small velocity magnitude discrepancies (2-8%); 2) with a Spearman's rank correlation ≥0.72; and 3) a velocity vector correlation (including direction) of r(2) ≥ 0.82. The highest agreement was achieved for high velocity regions with discrepancies being located in slow or recirculating zones with low MRI signal-to-noise ratio (SNRv ) in tortuous segments and large bifurcating vessels.
  
  
  
  Characterization of coronary flow using a dynamically scaled PC-MRI phantom flow is feasible and provides higher resolution than current in vivo or true-scale in vitro methods, and may be used to provide boundary conditions for true-scale CFD simulations. J. MAGN. RESON. IMAGING 2016;44:983-992.
authors.affiliation: University of Auckland, Auckland, New Zealand. s.beier@auckland.ac.nz.
authors.forename: Susann
authors.initials: S
authors.lastname: Beier
authors.affiliation: Mercy Angiography, Auckland, New Zealand.
authors.forename: John A
authors.initials: JA
authors.lastname: Ormiston
authors.affiliation: Auckland City Hospital, Auckland, New Zealand.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Webster
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: John E
authors.initials: JE
authors.lastname: Cater
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Stuart E
authors.initials: SE
authors.lastname: Norris
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Pau
authors.initials: P
authors.lastname: Medrano-Gracia
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Alistair A
authors.initials: AA
authors.lastname: Young
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Brett R
authors.initials: BR
authors.lastname: Cowan
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology*; D003198:Computer Simulation; D003326:Coronary Circulation / Q000502:physiology*; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000295:instrumentation* / Q000379:methods; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: CFD; coronaries; dynamic similarity; hemodynamics; phase-contrast MRI; scaled phantom flow