title: Four-dimensional fetal echocardiography with spatiotemporal image correlation (STIC): a systematic study of standard cardiac views assessed by different observers.
abstract: OBJECTIVE
  To test the agreement between observers and reproducibility of a technique to display standard cardiac views of the left and right ventricular outflow tracts from four-dimensional volume datasets acquired with Spatiotemporal Image Correlation (STIC).
  
  
  METHODS
  A technique was developed to obtain dynamic multiplanar images of the left ventricular outflow tract (LVOT) and right ventricular outflow tract (RVOT) from volume datasets acquired with STIC. Volume datasets were acquired from fetuses with normal cardiac anatomy. Twenty volume datasets of satisfactory quality were pre-selected by one investigator. The data was randomly assigned for a blinded review by two independent observers with previous experience in fetal echocardiography. Only one volume dataset was used for each fetus. After a training session, the observers obtained standardized cardiac views of the LVOT and RVOT, which were scored on a scale of 1 to 5, based on diagnostic value and image quality (1=unacceptable, 2=marginal, 3=acceptable, 4=good, and 5=excellent). Median scores and interquartile range, as well as inter- and intraobserver agreement were calculated for each view.
  
  
  RESULTS
  The mean menstrual age at the time of volume acquisition was 25.5+/-4.5 weeks. Median scores (interquartile range) for LVOT images, obtained by the first and second observers, were 3.5 (2.25-5.00) and 4 (3.00-5.00), respectively. The median scores (interquartile range) for RVOT images obtained by the first and second observers were 3 (3.00-5.00) and 3 (2.00-4.00), respectively. The interobserver intraclass correlation coefficient for the LVOT was 0.693 (95% CI 0.380-0.822), and 0.696 (95% CI 0.382-0.866) for the RVOT. For the intraobserver agreement analysis, observer 1 gave higher scores to the LVOT the second time the volumes were analyzed [LVOT: 3.50 (2.25-5.00) vs. 5.00 (4.00-5.00, p=0.008)].
  
  
  CONCLUSIONS
  STIC can be reproducibly used to evaluate fetal cardiac outflow tracts by independent examiners. Slightly better image quality rating scores during the intraobserver variability trial suggests the presence of a learning curve for the manipulation and analysis of volume data obtained by STIC.
authors.affiliation: Perinatology Research Branch, NICHD, NIH, DHHS, Bethesda, Maryland, USA.
authors.forename: Luís F
authors.initials: LF
authors.lastname: Gonçalves
authors.forename: Jimmy
authors.initials: J
authors.lastname: Espinoza
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Wesley
authors.initials: W
authors.lastname: Lee
authors.forename: Marjorie C
authors.initials: MC
authors.lastname: Treadwell
authors.forename: Raywin
authors.initials: R
authors.lastname: Huang
authors.forename: Greggory
authors.initials: G
authors.lastname: Devore
authors.forename: Tinnakorn
authors.initials: T
authors.lastname: Chaiworapongsa
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Schoen
authors.forename: Betsy
authors.initials: B
authors.lastname: Beyer
mesh_terms: D004311:Double-Blind Method; D019561:Echocardiography, Four-Dimensional; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging*; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D015588:Observer Variation; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal