title: Accuracy, agreement, and reliability of fetal cardiac measurements using 4-dimensional spatiotemporal image correlation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the accuracy, agreement, and reliability of 4-dimensional sonography using spatiotemporal image correlation (STIC) in fetal cardiac measurements during the second and third trimesters.
  
  
  METHODS
  Four-dimensional cardiac STIC volumes were acquired from 150 low-risk singleton pregnancies at gestational ages of 18 to 38 weeks. A total of 11 dimensions of the fetal heart and great vessels were analyzed by two different observers. Accuracy was assessed by comparing the measurements acquired by 4-dimensional STIC with those determined by 2-dimensional echocardiography by calculating the mean error and mean percent error and depicted by Bland-Altman plots. Absolute agreement and reliability of STIC-based measurements were evaluated on the basis of an intraclass correlation coefficient (ICC).
  
  
  RESULTS
  For STIC-based measurements of cardiac dimensions, good accuracy was achieved by the two experienced observers (mean percent error, -3.10% to 0.87% for observer A; -2.49% to -0.33% for observer B), and absolute agreement was almost perfect (ICC, 95% confidence interval, 0.916-0.993 for observer A; 0.957-0.990 for observer B). Interobserver ICCs among the two observers were between 0.909 and 0.990 (95% confidence interval), whereas intraobserver ICCs for observer A were between 0.894 and 0.989, and those for observer B were between 0.893 and 0.985, showing no significant differences in the reliability of SITC with regard to observers.
  
  
  CONCLUSIONS
  Four-dimensional sonography with STIC is a feasible and accurate method for fetal cardiac dimension measurements in the second and third trimesters. It is in good agreement with 2-dimensional echocardiography and can be performed by different observers.
authors.affiliation: Department of Ultrasonic Medicine, Fetal Medical Center, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.forename: Hong-ning
authors.initials: HN
authors.lastname: Xie
authors.forename: Ruan
authors.initials: R
authors.lastname: Peng
authors.forename: Ju
authors.initials: J
authors.lastname: Zheng
authors.forename: Yun-xiao
authors.initials: YX
authors.lastname: Zhu
mesh_terms: D000465:Algorithms; D019561:Echocardiography, Four-Dimensional / Q000379:methods*; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*