title: Right ventricular ejection fraction measurements using two-dimensional transthoracic echocardiography by applying an ellipsoid model.
abstract: BACKGROUND
  There is today no established approach to estimate right ventricular ejection fraction (RVEF) using 2D transthoracic echocardiography (TTE). The aim of this study was to evaluate a new method for RVEF calculations using 2D TTE and compare the results with cardiac magnetic resonance (CMR) imaging and tricuspid annular plane systolic excursion (TAPSE).
  
  
  METHODS
  A total of 37 subjects, 25 retrospectively included patients and twelve healthy volunteers, were included to give a wide range of RVEF. The right ventricle (RV) was modeled as a part of an ellipsoid enabling calculation of the RV volume by combining three distance measurements. RVEF calculated according to the model, RVEFTTE, were compared with reference CMR-derived RVEF, RVEFCMR. Further, TAPSE was measured in the TTE images and the correlations were calculated between RVEFTTE, TAPSE and RVEFCMR.
  
  
  RESULTS
  The mean values were RVEFCMR= 43 ± 12% (range 20-66%) and RVEFTTE= 50 ± 9% (range 34-65%). There was a high correlation (r = 0.80, p < 0.001) between RVEFTTEand RVEFCMR. Bland-Altman analysis showed a mean difference between RVEFCMRand RVEFTTEof 6 percentage points (ppt) with limits of agreement from -11 to 23 ppt. The mean value for TAPSE was 19 ± 5 mm and the correlation between TAPSE and RVEFCMRwas moderate (r = 0.54, p < 0.001). The correlation between RVEFTTEand RVEFCMRwas significantly higher (p < 0.05) than the correlation between TAPSE and RVEFCMR.
  
  
  CONCLUSIONS
  The ellipsoid model shows promise for RVEF calculations using 2D TTE for a wide range of RVEF, providing RVEF estimates that were significantly better correlated to RVEF obtained from CMR compared to TAPSE.
authors.affiliation: School of Medical Sciences, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden. stina.jorstig@regionorebrolan.se.|Biomedical Engineering, Örebro University Hospital, 70185, Örebro, Sweden. stina.jorstig@regionorebrolan.se.
authors.forename: Stina
authors.initials: S
authors.lastname: Jorstig
authors.affiliation: School of Medical Sciences, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden.|Department of Clinical Physiology, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden.
authors.forename: Micael
authors.initials: M
authors.lastname: Waldenborg
authors.affiliation: School of Medical Sciences, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden.|Department of Radiology, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Lidén
authors.affiliation: School of Medical Sciences, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden.|Department of Medical Physics, Faculty of Medicine and Health, Örebro University, 70182, Örebro, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Thunberg
mesh_terms: D000328:Adult; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013318:Stroke Volume / Q000502:physiology*; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis / Q000503:physiopathology*; D016278:Ventricular Function, Right / Q000502:physiology*
keywords: Cardiac magnetic resonance imaging; Echocardiography; Right ventricle; Right ventricular function