title: Image quality of the aortic and mitral valve with CT: relative versus absolute delay reconstruction.
abstract: OBJECTIVE
  The purpose of this study was to compare image quality and artifacts of 16-detector row CT imaging of the aortic and mitral valve when performing ECG-gated synchronization using relative and absolute reconstructions.
  
  
  METHODS
  Cardiac CT was performed in 22 consecutive patients; 20 data sets per RR interval were reconstructed with relative and absolute reconstructions. Mean and variability of heart rate during data acquisition were noted. Two readers assessed contrast media-related artifacts, calcification-related artifacts, ECG gating-related artifacts, and image quality in parallel and perpendicular planes.
  
  
  RESULTS
  Contrast media-related and calcification-related artifacts similarly occurred with both reconstruction techniques. ECG gating-related artifacts occurred in both valves more often with relative reconstructions than with absolute reconstructions (p = .001). Image quality was significantly better for absolute reconstructions for the open aortic cusp surface (p = .014) and edge (p = .008) in both planes, and of the closed mitral valve leaflets (p = .003) and apposition zone (p = .003) in perpendicular planes. Occurrence of ECG gating-related artifacts in both valves significantly correlated (p = .01) with heart rate variability for relative reconstructions, whereas no correlation was found using the absolute technique.
  
  
  CONCLUSIONS
  Absolute reconstructions allow CT imaging of the aortic and mitral valve with fewer artifacts and are less sensitive to heart rate variability as compared to relative reconstructions.
authors: Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland. thomas_boehm@gmx.net
authors: Thomas
authors: T
authors: Boehm
authors: Lars
authors: L
authors: Husmann
authors: Sebastian
authors: S
authors: Leschka
authors: Lotus
authors: L
authors: Desbiolles
authors: Borut
authors: B
authors: Marincek
authors: Hatem
authors: H
authors: Alkadhi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000473:pathology; D016477:Artifacts; D003287:Contrast Media; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000473:pathology; D009010:Monte Carlo Method; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol