title: Analysis of edge-tracking errors inherent in fluoroscopic images of the beating heart.
abstract: OBJECTIVE
  Because of the complex relationships between the dynamic three-dimensional cardiac surface shape and its projected image, errors arise with the use of two-dimensional silhouettes to measure displacements of the heart. The character and frequency of such errors are examined.
  
  
  METHODS
  A high-precision x-ray scatter imaging technique was used to reconstruct the three-dimensional shape of the left ventricular free wall throughout the cardiac cycle. Displacements of the three-dimensional surface were then compared with those on the two-dimensional projected silhouette. Silhouette displacement errors were determined as a function of time during the cardiac cycle and variability between hearts.
  
  
  RESULTS
  Differences between silhouette measurements and those on the cardiac surface range from 0% to 125% of peak-to-peak displacements occur, along 33% to 75% of the silhouette contours and cover 66% of the cardiac cycle.
  
  
  CONCLUSIONS
  Two-dimensional silhouette displacements provide inconsistent measurements of motion patterns on the three-dimensional cardiac surface.
authors.affiliation: Division of Cardiology, Milton S. Hershey Medical Center, Hershey, PA 17033.
authors.forename: J J
authors.initials: JJ
authors.lastname: McInerney
authors.forename: P W
authors.initials: PW
authors.lastname: Weldner
authors.forename: M D
authors.initials: MD
authors.lastname: Herr
authors.forename: G L
authors.initials: GL
authors.lastname: Copenhaver
mesh_terms: D000818:Animals; D004285:Dogs; D005471:Fluoroscopy; D006321:Heart / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted; D009200:Myocardial Contraction / Q000502:physiology*; D012542:Scattering, Radiation; D016277:Ventricular Function, Left / Q000502:physiology*