title: Three-Dimensional Field Optimization Method: Clinical Validation of a Novel Color Doppler Method for Quantifying Mitral Regurgitation.
abstract: Assessment of mitral regurgitation (MR) severity by echocardiography is important for clinical decision making, but MR severity can be challenging to quantitate accurately and reproducibly. The accuracy of effective regurgitant orifice area (EROA) and regurgitant volume (RVol) calculated using two-dimensional (2D) proximal isovelocity surface area is limited by the geometric assumptions of proximal isovelocity surface area shape, and both variables demonstrate interobserver variability. The aim of this study was to compare a novel automated three-dimensional (3D) echocardiographic method for calculating MR regurgitant flow using standard 2D techniques.
  
  
  
  A sheep model of ischemic MR and patients with MR were prospectively examined. Patients with a range of severity of MR were examined. EROA and RVol were calculated from 3D color Doppler acquisitions using a novel computer-automated algorithm based on the field optimization method to measure EROA and RVol. For an independent comparison group, the 3D field optimization method was compared with 2D methods for grading MR in an experimental ovine model of MR.
  
  
  
  Fifteen 3D data sets from nine sheep (open-chest transthoracic echocardiographic data sets) and 33 transesophageal data sets from patients with MR were prospectively examined. For sheep data sets, mean 2D EROA was 0.16 ± 0.05 cm2, and mean 2D RVol was 21.84 ± 8.03 mL. Mean 3D EROA was 0.09 ± 0.04 cm2, and mean 3D RVol was 14.40 ± 5.79 cm3. There was good correlation between 2D and 3D EROA (R = 0.70) and RVol (R = 0.80). For patient data sets, mean 2D EROA was 0.35 ± 0.35 cm2, and mean 2D RVol was 58.9 ± 52.9 mL. Mean 3D EROA was 0.34 ± 0.29 cm2, and mean 3D RVol was 54.6 ± 36.5 mL. There was excellent correlation between 2D and 3D EROA (R = 0.94) and RVol (R = 0.84). Bland-Altman analysis revealed greater interobserver variability for 2D RVol measurements compared with 3D RVol using the 3D field optimization method measurements, but variability was statistically significant only for RVol.
  
  
  
  Direct automated measurement of proximal isovelocity surface area region for EROA calculation using real-time 3D color Doppler echocardiography is feasible, with a high correlation to current 2D EROA methods but less variability. This novel automated method provides an accurate and highly reproducible method for calculating EROA.
authors.affiliation: Cardiac Ultrasound Laboratory, Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Tan
authors.affiliation: Cardiac Ultrasound Laboratory, Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Xin
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Cardiac Ultrasound Laboratory, Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: St. Francis Hospital, Roslyn, New York.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Philips Healthcare, Andover, Massachusetts.
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Philips Healthcare, Andover, Massachusetts.
authors.forename: Karl
authors.initials: K
authors.lastname: Thiele
authors.affiliation: Philips Healthcare, Andover, Massachusetts.
authors.forename: Ivan
authors.initials: I
authors.lastname: Salgo
authors.affiliation: Department of Anesthesiology, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Vipin
authors.initials: V
authors.lastname: Mehta
authors.affiliation: Department of Anesthesiology, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Michael
authors.initials: M
authors.lastname: Andrawes
authors.affiliation: Cardiac Ultrasound Laboratory, Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Picard
authors.affiliation: Cardiac Ultrasound Laboratory, Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. Electronic address: jhung@partners.org.
authors.forename: Judy
authors.initials: J
authors.lastname: Hung
mesh_terms: D000818:Animals; D018618:Echocardiography, Doppler, Color / Q000379:methods* / Q000592:standards*; D019560:Echocardiography, Three-Dimensional / Q000379:methods* / Q000592:standards*; D007089:Image Enhancement / Q000379:methods* / Q000592:standards*; D066298:In Vitro Techniques; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging*; D015588:Observer Variation; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012756:Sheep
keywords: Mitral regurgitation; Proximal isovelocity surface area; Three-dimensional echocardiography