title: Comparison of two different speckle tracking software systems: does the method matter?
abstract: BACKGROUND
  Echocardiographic speckle tracking strain has gained clinical importance. However, the comparability of measurements between different software systems is not well defined.
  
  
  METHODS
  In 47 healthy subjects left ventricular (LV) two-dimensional (2D) peak strain and time to peak strain (TTP) generated by EchoPAC (2DS) and velocity vector imaging (VVI) were compared. For each type of strain (longitudinal [LS], circumferential [CS], and radial strain [RS]) we compared global, anatomical level and segmental values.
  
  
  RESULTS
  When comparing 2DS to VVI, Pearson correlation coefficients (r) of global LS, CS, and RS were 0.68, 0.44, and 0.59, respectively (all P < 0.05). Correlation of global TTP was higher: 0.81(LS), 0.80 (CS), and 0.68 (RS), all P < 0.01. Segmental peak strain differed significantly between 2DS and VVI in 8/18 (LS), 17/18 (CS), and 15/18 (RS) LV segments (P < 0.05). However, segmental TTP significantly differed only in 5/18 (LS), 7/18 (CS), and 4/18 (RS) of LV segments. Similar strain gradients were found for both systems: apical strain was higher than basal and midventricular strain in LS and CS, with a reversed pattern for RS (P < 0.05).
  
  
  CONCLUSIONS
  TTP strain as well as strain gradients were comparable between VVI and 2DS, but most peak strain values were not. The software-dependency of peak strain values must be considered in clinical application. Further studies comparing the diagnostic and prognostic accuracy of strain values generated by different software systems are mandatory.
authors.affiliation: Division of Cardiology, Peter Munk Cardiac Program, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada. pbiaggi@gmx.ch
authors.forename: Patric
authors.initials: P
authors.lastname: Biaggi
authors.forename: Shemy
authors.initials: S
authors.lastname: Carasso
authors.forename: Patrick
authors.initials: P
authors.lastname: Garceau
authors.forename: Matthias
authors.initials: M
authors.lastname: Greutmann
authors.forename: Christiane
authors.initials: C
authors.lastname: Gruner
authors.forename: Wendy
authors.initials: W
authors.lastname: Tsang
authors.forename: Harry
authors.initials: H
authors.lastname: Rakowski
authors.forename: Yoram
authors.initials: Y
authors.lastname: Agmon
authors.forename: Anna
authors.initials: A
authors.lastname: Woo
mesh_terms: D000465:Algorithms; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D012986:Software Validation; D016277:Ventricular Function, Left / Q000502:physiology*