title: Quantitative mitral valve modeling using real-time three-dimensional echocardiography: technique and repeatability.
abstract: BACKGROUND
  Real-time three-dimensional (3D) echocardiography has the ability to construct quantitative models of the mitral valve (MV). Imaging and modeling algorithms rely on operator interpretation of raw images and may be subject to observer-dependent variability. We describe a comprehensive analysis technique to generate high-resolution 3D MV models and examine interoperator and intraoperator repeatability in humans.
  
  
  METHODS
  Patients with normal MVs were imaged using intraoperative transesophageal real-time 3D echocardiography. The annulus and leaflets were manually segmented using a TomTec Echo-View workstation. The resultant annular and leaflet point cloud was used to generate fully quantitative 3D MV models using custom Matlab algorithms. Eight images were subjected to analysis by two independent observers. Two sequential images were acquired for 6 patients and analyzed by the same observer. Each pair of annular tracings was compared with respect to conventional variables and by calculating the mean absolute distance between paired renderings. To compare leaflets, MV models were aligned so as to minimize their sum of squares difference, and their mean absolute difference was measured.
  
  
  RESULTS
  Mean absolute annular and leaflet distance was 2.4±0.8 and 0.6±0.2 mm for the interobserver and 1.5±0.6 and 0.5±0.2 mm for the intraobserver comparisons, respectively. There was less than 10% variation in annular variables between comparisons.
  
  
  CONCLUSIONS
  These techniques generate high-resolution, quantitative 3D models of the MV and can be used consistently to image the human MV with very small interoperator and intraoperator variability. These data lay the framework for reliable and comprehensive noninvasive modeling of the normal and diseased MV.
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Arminder Singh
authors.initials: AS
authors.lastname: Jassar
authors.forename: Clayton J
authors.initials: CJ
authors.lastname: Brinster
authors.forename: Mathieu
authors.initials: M
authors.lastname: Vergnat
authors.forename: J Daniel
authors.initials: JD
authors.lastname: Robb
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Eperjesi
authors.forename: Alison M
authors.initials: AM
authors.lastname: Pouch
authors.forename: Albert T
authors.initials: AT
authors.lastname: Cheung
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Weiss
authors.forename: Michael A
authors.initials: MA
authors.lastname: Acker
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Gorman
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gorman
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Jackson
mesh_terms: D019560:Echocardiography, Three-Dimensional; D017548:Echocardiography, Transesophageal; D006349:Heart Valve Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008943:Mitral Valve; D008955:Models, Cardiovascular; D016343:Monitoring, Intraoperative; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results