title: Feasibility of Automated Three-Dimensional Rotational Mechanics by Real-Time Volume Transthoracic Echocardiography: Preliminary Accuracy and Reproducibility Data Compared with Cardiovascular Magnetic Resonance.
abstract: BACKGROUND
  Three-dimensional (3D) speckle-tracking echocardiography (STE) for myocardial strain imaging may be superior to two-dimensional STE, especially with respect to rotational mechanics. Automated strain measurements from nonstitched 3D STE may improve work flow and clinical utility. The aim of this study was to test the feasibility of model-based 3D STE for the automated measurement of voxel circumferential strain (Ecc) and myocardial rotation.
  
  
  METHODS
  Thirty-five individuals (12 healthy volunteers, 12 patients with dilated cardiomyopathy, and 11 patients with hypertensive left ventricular [LV] hypertrophy) were prospectively studied. The latter two groups did not have significant coronary artery disease on coronary arteriography. Tagged cardiovascular magnetic resonance (CMR) and feature-tracking CMR were used as reference standards. Regional (apex and mid left ventricle) and slice (within a region) Ecc and rotation were measured by real-time volume transthoracic echocardiography (nonstitched) using an automated algorithm.
  
  
  RESULTS
  Compared with both CMR techniques, apical and mid-LV Ecc (concordance correlation coefficients [CCCs], 0.84-0.95 and 0.48-0.68) and rotation (CCCs, 0.70-0.95 and 0.42-0.68) showed excellent, good, and moderate agreement, respectively. At the LV base, rotation showed poor agreement with CMR methods (CCC, 0.04-0.21), consistent with previous descriptions, but calculated LV twist showed moderate to good correlation with CMR techniques (CCC, 0.61-0.84). However, the 95% CI for measurements between techniques was wide, emphasizing the challenges in comparing voxel deformation by 3D echocardiography with CMR, compounded by differences in approaches to measuring deformation, and matching regional and slice measurements between techniques. Reproducibility (n = 10, including test-retest variability) of automated 3D strain and rotation measurements was good to excellent (coefficient of variation < 10%) and was comparable with that of CMR methods (coefficient of variation < 10%) in the same patients.
  
  
  CONCLUSIONS
  The data from this study show that automated measurements of voxel rotational mechanics by real-time volume transthoracic echocardiography is feasible and comparable with tagged CMR and feature-tracking CMR strain measurements, albeit with wide limits of agreement, emphasizing the differences between the modalities. Furthermore, this automated 3D speckle-tracking echocardiographic approach shows excellent reproducibility, including test-retest variability, comparable with that of the CMR methods.
authors.affiliation: PLA General Hospital, Beijing, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Toronto General Hospital, Peter Munk Cardiac Center, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Paaladinesh
authors.initials: P
authors.lastname: Thavendiranathan
authors.affiliation: PLA General Hospital, Beijing, China.
authors.forename: Yundai
authors.initials: Y
authors.lastname: Chen
authors.affiliation: PLA General Hospital, Beijing, China.
authors.forename: Liuquan
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Piedmont Heart Institute, Atlanta, Georgia.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Qian
authors.affiliation: Piedmont Heart Institute, Atlanta, Georgia.
authors.forename: Shizhen
authors.initials: S
authors.lastname: Liu
authors.affiliation: Siemens Medical Solutions USA, Mountain View, California.
authors.forename: Helene
authors.initials: H
authors.lastname: Houle
authors.affiliation: PLA General Hospital, Beijing, China. Electronic address: guangzhi301@hotmail.com.
authors.forename: Guang
authors.initials: G
authors.lastname: Zhi
authors.affiliation: Piedmont Heart Institute, Atlanta, Georgia.
authors.forename: Mani A
authors.initials: MA
authors.lastname: Vannan
mesh_terms: D000328:Adult; D000465:Algorithms; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009206:Myocardium / Q000473:pathology*; D012372:ROC Curve; D015203:Reproducibility of Results; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: 3D speckle-tracking; 3D strain; Circumferential strain; LV twist; Myocardial rotation