title: 4D left ventricular resultant wall motion and blood flow assessed by phase-shift velocity mapping at high-field 3T MRI.
abstract: BACKGROUND
  Contractility and elasticity of the myocardium are important variables for detecting anomalies that may influence pump function. It is important to assess both wall motion and blood flow to detect regional left ventricular (LV) dysfunction and abnormal flow patterns. This study discusses four-dimensional (4D) phase-contrast magnetic resonance imaging (MRI) for simultaneous quantification and visualization of LV wall motion and blood flow.
  
  
  METHODS
  In thirteen healthy subjects, a three-directional retrospective cardiac triggered phase-shift velocity mapping technique was used to acquire velocity data of the LV throughout the cardiac cycle. All short-axis slices of the LV wall were segmented in six sectors of 60° starting from the anterior hinge point between the right and left ventricles, from base to apex. Velocity data in resultant, radial, circumferential and longitudinal directions were calculated and presented as coloured three-directional vectors.
  
  
  RESULTS
  Our findings showed a reduction in maximum wall velocities from base to apex, whereas for the radial and circumferential directions no significant differences were noted (13·1 ± 2·7 and 13·0 ± 2·9 cm s-1, respectively. P = 0·9). The longitudinal maximum velocities (21·0 ± 0·6 cm s-1) were significantly higher than the radial and circumferential components (P = 0·002). We found that the inclination angle of the resultant blood flow was changed towards the left ventricular outflow tract during systole.
  
  
  CONCLUSIONS
  Using this 4D MRI velocity mapping technique, we present an improved method for quantification and visualization of ventricular wall velocities in the radial, circumferential and longitudinal directions, as well as for the intracavity blood flow.
authors.affiliation: Department of Civil Engineering, Bergen University College, Bergen, Norway.|Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway.
authors.forename: Stig F
authors.initials: SF
authors.lastname: Samnøy
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Jochem
authors.initials: J
authors.lastname: Cuypers
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.|Department of Heart Disease, Haukeland University Hospital, Bergen, Norway.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Greve
authors.affiliation: Department of Heart Disease, Haukeland University Hospital, Bergen, Norway.|Department of Biomedicine, University of Bergen, Bergen, Norway.
authors.forename: Terje H
authors.initials: TH
authors.lastname: Larsen
mesh_terms: D055424:Cardiac-Gated Imaging Techniques; D004562:Electrocardiography; D064368:Healthy Volunteers; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006439:Hemodynamics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D009200:Myocardial Contraction; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D013997:Time Factors; D016277:Ventricular Function, Left
keywords: flow angles; left ventricular wall motion; magnetic resonance imaging; quantification; three-directional velocity vector imaging; visualization