title: Vortex flow during early and late left ventricular filling in normal subjects: quantitative characterization using retrospectively-gated 4D flow cardiovascular magnetic resonance and three-dimensional vortex core analysis.
abstract: BACKGROUND
  LV diastolic vortex formation has been suggested to critically contribute to efficient blood pumping function, while altered vortex formation has been associated with LV pathologies. Therefore, quantitative characterization of vortex flow might provide a novel objective tool for evaluating LV function. The objectives of this study were 1) assess feasibility of vortex flow analysis during both early and late diastolic filling in vivo in normal subjects using 4D Flow cardiovascular magnetic resonance (CMR) with retrospective cardiac gating and 3D vortex core analysis 2) establish normal quantitative parameters characterizing 3D LV vortex flow during both early and late ventricular filling in normal subjects.
  
  
  METHODS
  With full ethical approval, twenty-four healthy volunteers (mean age: 20±10 years) underwent whole-heart 4D Flow CMR. The Lambda2-method was used to extract 3D LV vortex ring cores from the blood flow velocity field during early (E) and late (A) diastolic filling. The 3D location of the center of vortex ring core was characterized using cylindrical cardiac coordinates (Circumferential, Longitudinal (L), Radial (R)). Comparison between E and A filling was done with a paired T-test. The orientation of the vortex ring core was measured and the ring shape was quantified by the circularity index (CI). Finally, the Spearman's correlation between the shapes of mitral inflow pattern and formed vortex ring cores was tested.
  
  
  RESULTS
  Distinct E- and A-vortex ring cores were observed with centers of A-vortex rings significantly closer to the mitral valve annulus (E-vortex L=0.19±0.04 versus A-vortex L=0.15±0.05; p=0.0001), closer to the ventricle's long-axis (E-vortex: R=0.27±0.07, A-vortex: R=0.20±0.09, p=0.048) and more elliptical in shape (E-vortex: CI=0.79±0.09, A-vortex: CI=0.57±0.06; <0.001) compared to E-vortex. The circumferential location and orientation relative to LV long-axis for both E- and A-vortex ring cores were similar. Good to strong correlation was found between vortex shape and mitral inflow shape through both the annulus (r=0.66) and leaflet tips (r=0.83).
  
  
  CONCLUSIONS
  Quantitative characterization and comparison of 3D vortex rings in LV inflow during both early and late diastolic phases is feasible in normal subjects using retrospectively-gated 4D Flow CMR, with distinct differences between early and late diastolic vortex rings.
authors.forename: Mohammed S M
authors.initials: MS
authors.lastname: Elbaz
authors.forename: Emmeline E
authors.initials: EE
authors.lastname: Calkoen
authors.forename: Jos J M
authors.initials: JJ
authors.lastname: Westenberg
authors.forename: Boudewijn P F
authors.initials: BP
authors.lastname: Lelieveldt
authors.forename: Arno A W
authors.initials: AA
authors.lastname: Roest
authors.forename: Rob J
authors.initials: RJ
authors.lastname: van der Geest
mesh_terms: D000293:Adolescent; D000328:Adult; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D002648:Child; D005240:Feasibility Studies; D005260:Female; D064368:Healthy Volunteers; D006439:Hemodynamics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D015588:Observer Variation; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors; D016277:Ventricular Function, Left; D055815:Young Adult