title: Temporal and spatial performance of vector velocity imaging in the human fetal heart.
abstract: OBJECTIVE
  To assess the spatial and temporal performance of fetal myocardial speckle tracking, using high-frame-rate (HFR) storing and Lagrangian strain analysis.
  
  
  METHODS
  Dummy electrocardiographic signaling permitted DICOM HFR in 124 normal fetuses and paired low-frame-rate (LFR) video storing at 25 Hz in 93 of them. Vector velocity imaging (VVI) tracking co-ordinates were used to compare time and spatial domain measures. We compared tracking success, Lagrangian strain, peak diastolic velocity and positive strain rate values in HFR vs. LFR video storing. Further comparisons within an HFR subset included Lagrangian vs. natural strain, VVI vs. M-mode annular displacement, and VVI vs. pulsed-wave tissue Doppler imaging (TDI) peak velocities.
  
  
  RESULTS
  HFR (average 79.4 Hz) tracking was more successful than LFR (86 vs. 76%, P = 0.024). Lagrangian and natural HFR strain correlated highly (left ventricle (LV): r = 0.883, P < 0.001; right ventricle (RV): r = 0.792, P < 0.001) but natural strain gave 20% lower values, suggesting reduced reliability of measurement. Lagrangian HFR strain was similar in LV and RV and decreased with gestation (P = 0.015 and P < 0.001, respectively). LV Lagrangian LFR strain was significantly lower than the values for the RV (P < 0.001) and those using paired LV-HFR recordings (P = 0.007). Annular displacement methods correlated highly (LV = 1.046, r = 0.90, P < 0.001; RV = 1.170, r = 0.88, P < 0.001). Early diastolic waves were visible in 95% of TDI, but in only 26% of HFR and 0% of LFR recordings, and HFR-VVI velocities were significantly lower than those for TDI (P < 0.001).
  
  
  CONCLUSIONS
  Doppler estimation of velocities remains superior to VVI but image gating and use of original co-ordinates should improve offline VVI assessment of fetal myocardial function.
authors.affiliation: Department of Reproductive Biology, Imperial College at Queen Charlotte's and Chelsea Hospital, London, UK.
authors.forename: H
authors.initials: H
authors.lastname: Matsui
authors.forename: I
authors.initials: I
authors.lastname: Germanakis
authors.forename: E
authors.initials: E
authors.lastname: Kulinskaya
authors.forename: H M
authors.initials: HM
authors.lastname: Gardiner
mesh_terms: D015150:Echocardiography, Doppler / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D016277:Ventricular Function, Left / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*