title: Repositioning precision of coronary arteries measured on X-ray angiography and its implications for coronary MR angiography.
abstract: BACKGROUND
  To test the hypothesis that intervals with superior beat-to-beat coronary artery repositioning precision exist in the cardiac cycle, to design a coronary MR angiography (MRA) methodology in response, and to ascertain its performance.
  
  
  METHODS
  Coronary repositioning precision in consecutive heartbeats was measured on x-ray coronary angiograms of 17 patients and periods with the highest repositioning precision were identified. In response, the temporal order of coronary MRA pulse sequence elements required modification and the T2 -prep now follows (T2 -post) rather than precedes the imaging part of the sequence. The performance of T2 -post was quantitatively compared (signal-to-noise [SNR], contrast-to-noise [CNR], vessel sharpness) to that of T2 -prep in vivo.
  
  
  RESULTS
  Coronary repositioning precision is <1 mm at peak systole and in mid diastole. When comparing systolic T2 -post to diastolic T2 -prep, CNR and vessel sharpness remained unchanged (both P = NS) but SNR for muscle and blood increased by 104% and 36% (both P < 0.05), respectively.
  
  
  CONCLUSIONS
  Windows with improved coronary repositioning precision exist in the cardiac cycle: one in peak systole and one in mid diastole. Peak-systolic imaging necessitates a re-design of conventional coronary MRA pulse sequences and leads to image quality very similar to that of conventional mid-diastolic data acquisition but improved SNR.
authors.affiliation: Center for Biomedical Imaging (CIBM), Lausanne, Switzerland; Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
authors.forename: Simone
authors.initials: S
authors.lastname: Coppo
authors.forename: Maria
authors.initials: M
authors.lastname: Firsova
authors.forename: Didier
authors.initials: D
authors.lastname: Locca
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Knebel
authors.forename: Ruud B
authors.initials: RB
authors.lastname: van Heeswijk
authors.forename: Matthias
authors.initials: M
authors.lastname: Stuber
mesh_terms: D000368:Aged; D059925:Anatomic Landmarks / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D016477:Artifacts; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D056888:Patient Positioning / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: T2 preparation; coronary arteries; magnetic resonance angiography; systolic imaging