title: Feasibility and reproducibility of systolic right ventricular strain measurement by speckle-tracking echocardiography in premature infants.
abstract: BACKGROUND
  Right ventricular (RV) systolic function is an important prognostic determinant of cardiopulmonary pathologies in premature infants. Measurements of dominant RV longitudinal deformation are likely to provide a sensitive measure of RV function. An approach for image acquisition and postacquisition processing is needed for reliable and reproducible measurements of myocardial deformation by two-dimensional (2D) speckle-tracking echocardiography. The aims of this study were to determine the feasibility and reproducibility of 2D speckle-tracking echocardiographic measurement of RV peak global longitudinal strain (pGLS) and peak global longitudinal strain rate in premature infants and to establish methods for acquiring and analyzing strain.
  
  
  METHODS
  The study was designed in two phases: (1) a training phase to develop methods of image acquisition and postprocessing in a cohort of 30 premature infants (born at 28 ± 1 weeks) and (2) a study phase to prospectively test in a separate cohort of 50 premature infants (born at 27 ± 1 weeks) if the methods improved the feasibility and reproducibility of RV pGLS and peak global longitudinal strain rate measurements to a clinically significant level, assessed using Bland-Altman analysis (bias, limits of agreement, coefficient of variation, and intraclass correlation coefficient).
  
  
  RESULTS
  Strain imaging was feasible from 84% of the acquisitions using the methods developed for optimal speckle brightness and frame rate for RV-focused image acquisition. There was high intraobserver (bias, 3%; 95% limits of agreement, -1.6 to +1.6; coefficient of variation, 2.7%; intraclass correlation coefficient, 0.97; P = .02) and interobserver (bias, 7%; 95% limits of agreement, -4.8 to +4.73; coefficient of variation, 3.9%; intraclass correlation coefficient, 0.93; P < .05) reproducibility, with excellent linear correlation between the two pGLS measurements (r = 0.97 [P < .01] and r = 0.93 [P < .05], respectively).
  
  
  CONCLUSIONS
  This study demonstrates high clinical feasibility and reproducibility of RV pGLS and RV peak global longitudinal strain rate measurements by 2D speckle-tracking echocardiography in premature infants and offers methods for image acquisition and data analysis for systolic strain imaging that can provide a reliable assessment of global RV function.
authors.affiliation: Department of Pediatrics and the Department of Physics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Philip Thaler
authors.initials: PT
authors.lastname: Levy
authors.affiliation: Department of Pediatrics and the Department of Physics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Holland
authors.affiliation: Department of Pediatrics and the Department of Physics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Sekarski
authors.affiliation: Department of Pediatrics and the Department of Physics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Aaron
authors.initials: A
authors.lastname: Hamvas
authors.affiliation: Department of Pediatrics and the Department of Physics, Washington University School of Medicine, St. Louis, Missouri. Electronic address: singh_g@kids.wustl.edu.
authors.forename: Gautam K
authors.initials: GK
authors.lastname: Singh
mesh_terms: D004452:Echocardiography / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011379:Prognosis; D015203:Reproducibility of Results; D013599:Systole / Q000502:physiology
keywords: 2D; CI; CV; Coefficient of variation; Confidence interval; DTI; Doppler tissue imaging; Global longitudinal strain; ICC; Intraclass correlation coefficient; LOA; Limits of agreement; PMA; Peak global longitudinal strain; Peak global longitudinal strain rate; Postmenstrual age; Premature infants; ROI; RV; Region of interest; Right ventricle; Right ventricular; STE; Speckle-tracking echocardiography; Systolic function; Two-dimensional; pGLS; pGLSr