title: Accuracy and reproducibility of right ventricular quantification in patients with pressure and volume overload using single-beat three-dimensional echocardiography.
abstract: BACKGROUND
  The right ventricle is a complex structure that is challenging to quantify by two-dimensional (2D) echocardiography. Unlike disk summation three-dimensional (3D) echocardiography (3DE), single-beat 3DE can acquire large volumes at high volume rates in one cardiac cycle, avoiding stitching artifacts or long breath-holds. The aim of this study was to assess the accuracy and test-retest reproducibility of single-beat 3DE for quantifying right ventricular (RV) volumes in adult populations of acquired RV pressure or volume overload, namely, pulmonary hypertension (PH) and carcinoid heart disease, respectively. Three-dimensional and 2D echocardiographic indices were also compared for identifying RV dysfunction in PH.
  
  
  METHODS
  A prospective cross-sectional study was performed in 100 individuals who underwent 2D echocardiography, 3DE, and cardiac magnetic resonance imaging: 49 patients with PH, 20 with carcinoid heart disease, 11 with metastatic carcinoid tumors without cardiac involvement, and 20 healthy volunteers. Two operators performed test-retest acquisition and postprocessing for inter- and intraobserver reproducibility in 20 subjects.
  
  
  RESULTS
  RV single-beat 3DE was attainable in 96% of cases, with mean volume rates of 32 to 45 volumes/sec. Bland-Altman analysis of all subjects (presented as mean bias ± 95% limits of agreement) revealed good agreement for end-diastolic volume (-2.3 ± 27.4 mL) and end-systolic volume (5.2 ± 19.0 mL) measured by 3DE and cardiac magnetic resonance imaging, with a tendency to underestimate stroke volume (-7.5 ± 23.6 mL) and ejection fraction (-4.6 ± 13.8%) by 3DE. Subgroup analysis demonstrated a greater bias for volumetric underestimation, particularly in healthy volunteers (end-diastolic volume, -11.9 ± 18.0 mL; stroke volume, -11.2 ± 20.2 mL). Receiver operating characteristic curve analysis showed that 3DE-derived ejection fraction was significantly superior to 2D echocardiographic parameters for identifying RV dysfunction in PH (sensitivity, 94%; specificity, 88%; area under the curve, 0.95; P = .031). There was significant interobserver test-retest bias for RV volume underestimation (end-diastolic volume, -12.5 ± 28.1 mL; stroke volume, -10.6 ± 23.2 mL).
  
  
  CONCLUSIONS
  Single-beat 3DE is feasible and clinically applicable for volumetric quantification in acquired RV pressure or volume overload. It has improved limits of agreement compared with previous disk summation 3D echocardiographic studies and has incremental value over standard 2D echocardiographic measures for identifying RV dysfunction. Despite the ability to obtain and postprocess a full-volume 3D echocardiographic RV data set, the quality of the raw data did influence the accuracy of the data obtained. The technique performs better with dilated rather than nondilated RV cavities, with a learning curve that might affect the test-retest reproducibility for serial RV studies.
authors.affiliation: University College London Medical School, Royal Free Campus, London, United Kingdom; Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom; UCL Centre for Cardiovascular Imaging, University College London, London, United Kingdom. Electronic address: danielknight@doctors.org.uk.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Knight
authors.affiliation: Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors.forename: Agata E
authors.initials: AE
authors.lastname: Grasso
authors.affiliation: UCL Centre for Cardiovascular Imaging, University College London, London, United Kingdom.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Quail
authors.affiliation: UCL Centre for Cardiovascular Imaging, University College London, London, United Kingdom.
authors.forename: Vivek
authors.initials: V
authors.lastname: Muthurangu
authors.affiliation: UCL Centre for Cardiovascular Imaging, University College London, London, United Kingdom.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Taylor
authors.affiliation: Neuroendocrine Tumour Unit, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors.forename: Christos
authors.initials: C
authors.lastname: Toumpanakis
authors.affiliation: Neuroendocrine Tumour Unit, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors.forename: Martyn E
authors.initials: ME
authors.lastname: Caplin
authors.affiliation: Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors.forename: J Gerry
authors.initials: JG
authors.lastname: Coghlan
authors.affiliation: Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors.forename: Joseph
authors.initials: J
authors.lastname: Davar
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging*
keywords: Carcinoid heart disease; Magnetic resonance imaging; Pulmonary hypertension; Right ventricular function; Three-dimensional echocardiography