title: Variables influencing the accuracy of 2-dimensional and real-time 3-dimensional echocardiography for assessment of small volumes, areas, and distances: an in vitro study using static tissue-mimicking phantoms.
abstract: OBJECTIVE
  The aim of this study was to assess the validity, accuracy, and reproducibility of real-time 3-dimensional (3D) echocardiography for small distances, areas, and volumes.
  
  
  METHODS
  Real-time 3D echocardiography using matrix technology was performed in small calibrated tissue-mimicking phantoms and compared with 2-dimensional (2D) echocardiography. In a systematic variation of variables on data acquisition and analysis including different 3D workstations (manual disk summation versus semiautomatic border detection), the relative contributions of sources of errors were determined. The clinical relevance of the in vitro findings was assessed in 5 neonates and infants.
  
  
  RESULTS
  Distance calculation was valid (mean relative error ± SD, -0.15% ± 1.2%). Underestimation of areas and volumes was significant for both 2D and 3D echocardiography (area: 2D, -7.0% ± 2.9%; 3D, -6.0% ± 2.8%; volume: 2D, -13.1% ± 4.5%; 3D, -6.7% ± 2.5%; P < .05). Adjustment of compression and gain on data acquisition (difference of the means: 2D, 11.6%; 3D, 17.9%), gain on postprocessing (3D, 3.4%), and the border detection algorithm on analysis (2D, 4.8%; 3D, 16.6%) had a highly significant effect on volume and area calculations (P < .001). In vivo, compression and gain on acquisition (3D, 19.1%) and the 3D workstation on analysis (3D, 22.2%) had a highly significant impact on left ventricular volumetry (P < .001).
  
  
  CONCLUSIONS
  Real-time 3D echocardiography is a reliable method for calculation of small distances, areas, and volumes comparable with the size of the neonatal and infant heart. Variables influencing boundary identification during image acquisition and analysis have a significant impact on 2D and 3D area and volume calculations. Standardized protocols are mandatory to avoid these sources of error in both clinical practice and research.
authors.affiliation: Department of Pediatric Cardiology, University of Bonn, Adenauerallee 119, 53113 Bonn, Germany. ulrike.herberg@ukb.uni-bonn.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Herberg
authors.forename: Manuel
authors.initials: M
authors.lastname: Brand
authors.forename: Christine
authors.initials: C
authors.lastname: Bernhardt
authors.forename: Hans Georg
authors.initials: HG
authors.lastname: Trier
authors.forename: Johannes
authors.initials: J
authors.lastname: Breuer
mesh_terms: D000704:Analysis of Variance; D004452:Echocardiography / Q000379:methods*; D019560:Echocardiography, Three-Dimensional; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D007231:Infant, Newborn; D019047:Phantoms, Imaging; D015203:Reproducibility of Results