title: Retrospective reconstruction of cardiac cine images from golden-ratio radial MRI using one-dimensional navigators.
abstract: OBJECTIVE
  To demonstrate radial golden-ratio-based cardiac cine imaging by using interspersed one-dimensional (1D) navigators.
  
  
  METHODS
  The 1D navigators were interspersed into the acquisition of radial spokes which were continuously rotated by an angle increment based on the golden-ratio. Performing correlation analysis between the 1D navigator projections, time points corresponding to the same cardiac motion phases were automatically identified and used to combine retrospectively golden-ratio rotated radial spokes from multiple data windows. Data windows were shifted consecutively for dynamic reconstruction of different cardiac motion frames. Experiments were performed during a single breathhold. By artificially reducing the amount of input data, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as artifact level was evaluated for different breathhold durations.
  
  
  RESULTS
  Analysis of the 1D navigator data provided a detailed correlation function revealing cardiac motion over time. Imaging results were comparable to images reconstructed based on a timely synchronized ECG. Cardiac cine images with a low artifact level and good image quality in terms of SNR and CNR were reconstructed from volunteer data achieving a CNR between the myocardium and the left ventricular cavity of 50 for the longest breathhold duration of 26 s. CNR maintained a value higher than 30 for acquisition times as low as 10 s.
  
  
  CONCLUSIONS
  Combining radial golden-ratio-based imaging with an intrinsic navigator is a promising and robust method for performing high quality cardiac cine imaging.
authors.affiliation: Medical Physics Group, Institute of Diagnostic and Interventional Radiology I, Jena University Hospital - Friedrich Schiller University Jena, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Krämer
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Herrmann
authors.forename: Judith
authors.initials: J
authors.lastname: Biermann
authors.forename: Jurgen R
authors.initials: JR
authors.lastname: Reichenbach
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
keywords: cardiac cine imaging; projection reconstruction; radial acquisition; real-time imaging