title: Accuracy and limitations of vector flow mapping: left ventricular phantom validation using stereo particle image velocimetory.
abstract: The accuracy of vector flow mapping (VFM) was investigated in comparison to stereo particle image velocimetry (stereo-PIV) measurements using a left ventricular phantom. VFM is an echocardiographic approach to visualizing two-dimensional flow dynamics by estimating the azimuthal component of flow from the mass-conservation equation. VFM provides means of visualizing cardiac flow, but there has not been a study that compared the flow estimated by VFM to the flow data acquired by other methods.
  
  
  
  A reproducible three-dimensional cardiac blood flow was created in an optically and acoustically transparent left-ventricle phantom, that allowed color-flow mapping (CFM) data and stereo-PIV to be simultaneously acquired on the same plane. A VFM algorithm was applied to the CFM data, and the resulting VFM estimation and stereo-PIV data were compared to evaluate the accuracy of VFM.
  
  
  
  The velocity fields acquired by VFM and stereo-PIV were in excellent agreement in terms of the principle flow features and time-course transitions of the main vortex characteristics, i.e., the overall correlation of VFM and PIV vectors was R = 0.87 (p < 0.0001). The accuracy of VFM was suggested to be influenced by both CFM signal resolution and the three-dimensional flow, which violated the algorithm's assumption of planar flow. Statistical analysis of the vectors revealed a standard deviation of discrepancy averaging at 4.5% over the CFM velocity range for one cardiac cycle, and that value fluctuated up to 10% depending on the phase of the cardiac cycle.
  
  
  
  VFM provided fairly accurate two-dimensional-flow information on cardio-hemodynamics. These findings on VFM accuracy provide the basis for VFM-based diagnosis.
authors.affiliation: Hitachi Ltd, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Asami
authors.affiliation: Hitachi Ltd, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo, Japan. tomohiko.tanaka.nx@hitachi.com.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Hitachi Ltd, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo, Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Kawabata
authors.affiliation: Hitachi Ltd, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Hashiba
authors.affiliation: Hitachi Ltd, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.affiliation: Hitachi Ltd, 1-280 Higashi-Koigakubo, Kokubunji, Tokyo, Japan.
authors.forename: Tomohide
authors.initials: T
authors.lastname: Nishiyama
mesh_terms: D001783:Blood Flow Velocity; D003287:Contrast Media; D004452:Echocardiography / Q000379:methods; D006352:Heart Ventricles; D006439:Hemodynamics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008955:Models, Cardiovascular; D055095:Optics and Photonics; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012212:Rheology / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology
chemical_list: D003287:Contrast Media
keywords: Cardio-hemodynamics; Doppler ultrasound; Flow imaging; Ultrasonics