title: Accuracy and Test-Retest Reproducibility of Two-Dimensional Knowledge-Based Volumetric Reconstruction of the Right Ventricle in Pulmonary Hypertension.
abstract: BACKGROUND
  Right heart function is the key determinant of symptoms and prognosis in pulmonary hypertension (PH), but the right ventricle has a complex geometry that is challenging to quantify by two-dimensional (2D) echocardiography. A novel 2D echocardiographic technique for right ventricular (RV) quantitation involves knowledge-based reconstruction (KBR), a hybrid of 2D echocardiography-acquired coordinates localized in three-dimensional space and connected by reference to a disease-specific RV shape library. The aim of this study was to determine the accuracy of 2D KBR against cardiac magnetic resonance imaging in PH and the test-retest reproducibility of both conventional 2D echocardiographic RV fractional area change (FAC) and 2D KBR.
  
  
  METHODS
  Twenty-eight patients with PH underwent same-day echocardiography and cardiac magnetic resonance imaging. Two operators performed serial RV FAC and 2D KBR acquisition and postprocessing to assess inter- and intraobserver test-retest reproducibility.
  
  
  RESULTS
  Bland-Altman analysis (mean bias ± 95% limits of agreement) showed good agreement for end-diastolic volume (3.5 ± 25.0 mL), end-systolic volume (0.9 ± 19.9 mL), stroke volume (2.6 ± 23.1 mL), and ejection fraction (0.4 ± 10.2%) measured by 2D KBR and cardiac magnetic resonance imaging. There were no significant interobserver or intraobserver test-retest differences for 2D KBR RV metrics, with acceptable limits of agreement (interobserver end-diastolic volume, -0.9 ± 21.8 mL; end-systolic volume, -1.3 ± 25.8 mL; stroke volume, -0.2 ± 24.2 mL; ejection fraction, 0.7 ± 14.4%). Significant test-retest variability was observed for 2D echocardiographic RV areas and FAC.
  
  
  CONCLUSIONS
  Two-dimensional KBR is an accurate, novel technique for RV volumetric quantification in PH, with superior test-retest reproducibility compared with conventional 2D echocardiographic RV FAC.
authors: University College London Medical School, 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: Daniel S
authors: DS
authors: Knight
authors: Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors: Johannes P
authors: JP
authors: Schwaiger
authors: UCL Centre for Cardiovascular Imaging, University College London, London, United Kingdom.
authors: Sylvia
authors: S
authors: Krupickova
authors: Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors: Joseph
authors: J
authors: Davar
authors: UCL Centre for Cardiovascular Imaging, University College London, London, United Kingdom.
authors: Vivek
authors: V
authors: Muthurangu
authors: Department of Cardiology, Royal Free London NHS Foundation Trust, London, United Kingdom.
authors: J Gerry
authors: JG
authors: Coghlan
mesh_terms: D004452:Echocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications* / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D051188:Knowledge Bases; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging* / Q000209:etiology*
keywords: Magnetic resonance imaging; Pulmonary hypertension; Reproducibility of results; Right ventricular function; Transthoracic echocardiography