title: Variability in tissue Doppler echocardiographic measures of dyssynchrony is reduced with use of a larger region of interest.
abstract: BACKGROUND
  Doppler tissue imaging (DTI)-based dyssynchrony parameters failed to predict response to cardiac resynchronization therapy (CRT) in the multicenter Predictors of Response to Cardiac Resynchronization Therapy (PROSPECT) trial. Large variability during the interpretation of DTI data was one of several factors thought to contribute to this failure. In this study, the authors hypothesized that using larger regions of interest (ROIs) to generate velocity curves from Doppler tissue images would significantly reduce the variability of DTI dyssynchrony parameters.
  
  
  METHODS
  The variability of 3 ROI sizes (6 x 6, 18 x 6, and 30 x 6 mm) was compared in 30 patients undergoing CRT. Variability due to manual ROI placement was determined for each ROI size by placing 3 ROIs in each myocardial segment, 6mm apart from one another. Thus, 3 velocity curves were generated for each segment and each ROI size. Four published dyssynchrony parameters were calculated from all permutations of the 3 ROI positions per segment. A mean modified coefficient of variation was calculated for each parameter and ROI size.
  
  
  RESULTS
  The 6 x 6 mm ROI had a mean coefficient of variation of 27%. The 18 x 6 and 30 x 6 mm ROIs had significantly lower coefficients of variation (17% and 14%, respectively) than the 6 x 6 mm ROI (P < .01 for both). The 30 x 6 mm ROI also reduced the diagnostic inconsistency of dyssynchrony parameters by 44% (P = .024) compared with the 6 x 6 mm ROI.
  
  
  CONCLUSIONS
  Using a 30 x 6 mm ROI instead of a 6 x 6 mm ROI to quantify tissue Doppler dyssynchrony reduces variability by 47% and diagnostic inconsistency by 44%. The authors recommend using a 30 x 6 mm ROI in future trials to minimize variability.
authors.affiliation: Emory University School of Medicine, Atlanta, GA 30322, USA. bfornwa@emory.edu
authors.forename: Brandon K
authors.initials: BK
authors.lastname: Fornwalt
authors.forename: William W
authors.initials: WW
authors.lastname: Sprague
authors.forename: John D
authors.initials: JD
authors.lastname: Carew
authors.forename: John D
authors.initials: JD
authors.lastname: Merlino
authors.forename: Derek A
authors.initials: DA
authors.lastname: Fyfe
authors.forename: Angel R
authors.initials: AR
authors.lastname: León
authors.forename: John N
authors.initials: JN
authors.lastname: Oshinski
mesh_terms: D015150:Echocardiography, Doppler / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000000981:diagnostic imaging* / Q000517:prevention & control; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000150:complications* / Q000000981:diagnostic imaging* / Q000517:prevention & control