title: Assessment of cardiac time intervals using high temporal resolution real-time spiral phase contrast with UNFOLDed-SENSE.
abstract: OBJECTIVE
  To develop a real-time phase contrast MR sequence with high enough temporal resolution to assess cardiac time intervals.
  
  
  METHODS
  The sequence utilized spiral trajectories with an acquisition strategy that allowed a combination of temporal encoding (Unaliasing by fourier-encoding the overlaps using the temporal dimension; UNFOLD) and parallel imaging (Sensitivity encoding; SENSE) to be used (UNFOLDed-SENSE). An in silico experiment was performed to determine the optimum UNFOLD filter. In vitro experiments were carried out to validate the accuracy of time intervals calculation and peak mean velocity quantification. In addition, 15 healthy volunteers were imaged with the new sequence, and cardiac time intervals were compared to reference standard Doppler echocardiography measures. For comparison, in silico, in vitro, and in vivo experiments were also carried out using sliding window reconstructions.
  
  
  RESULTS
  The in vitro experiments demonstrated good agreement between real-time spiral UNFOLDed-SENSE phase contrast MR and the reference standard measurements of velocity and time intervals. The protocol was successfully performed in all volunteers. Subsequent measurement of time intervals produced values in keeping with literature values and good agreement with the gold standard echocardiography. Importantly, the proposed UNFOLDed-SENSE sequence outperformed the sliding window reconstructions.
  
  
  CONCLUSIONS
  Cardiac time intervals can be successfully assessed with UNFOLDed-SENSE real-time spiral phase contrast. Real-time MR assessment of cardiac time intervals may be beneficial in assessment of patients with cardiac conditions such as diastolic dysfunction.
authors.affiliation: UCL Institute of Cardiovascular Science, Centre for Cardiovascular Imaging, London, United Kingdom.
authors.forename: Grzegorz T
authors.initials: GT
authors.lastname: Kowalik
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Knight
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Steeden
authors.forename: Oliver
authors.initials: O
authors.lastname: Tann
authors.forename: Freddy
authors.initials: F
authors.lastname: Odille
authors.forename: David
authors.initials: D
authors.lastname: Atkinson
authors.forename: Andrew
authors.initials: A
authors.lastname: Taylor
authors.forename: Vivek
authors.initials: V
authors.lastname: Muthurangu
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D016477:Artifacts; D003199:Computer Systems; D003287:Contrast Media; D005260:Female; D006352:Heart Ventricles / 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; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D003287:Contrast Media
keywords: UNFOLD; cardiac timing intervals; real-time spiral PC-MR