title: Ungated radial quiescent-inflow single-shot (UnQISS) magnetic resonance angiography using optimized azimuthal equidistant projections.
abstract: OBJECTIVE
  We hypothesized that non-contrast-enhanced MR angiography (NEMRA) could be performed without cardiac gating by using a variant of the quiescent-inflow single-shot (QISS) technique.
  
  
  METHODS
  Ungated QISS (UnQISS) MRA was evaluated in eight patients with peripheral arterial disease at 1.5T. The radial acquisition used optimized azimuthal equidistant projections, a long quiescent inflow time (1200 ms) to ensure replenishment of saturated in-plane spins irrespective of the cardiac phase, and a lengthy readout (1200 ms) so that a complete cardiac cycle was sampled for each slice. Venous and background tissue suppression was obtained using frequency-offset-corrected inversion radiofrequency pulses.
  
  
  RESULTS
  Scan time for UnQISS was 15.4 min for an eight-station whole-leg acquisition. The appearance of UnQISS MRA acquired using the body coil was comparable to electrocardiographic-gated QISS MRA using phased array coils. A small radial view angle increment minimized eddy current-related artifacts, whereas image quality was inferior with a golden view angle radial increment or Cartesian trajectory. In patient studies, ≥50% stenoses were consistently detected.
  
  
  CONCLUSIONS
  Using UnQISS, peripheral NEMRA can be performed without the need for cardiac gating. The use of fixed imaging parameters and body coil for signal reception further simplifies the scan procedure.
authors.affiliation: NorthShore University HealthSystem, Evanston, Illinois, USA; Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Edelman
authors.forename: Shivraman
authors.initials: S
authors.lastname: Giri
authors.forename: Ian G
authors.initials: IG
authors.lastname: Murphy
authors.forename: Oisin
authors.initials: O
authors.lastname: Flanagan
authors.forename: Peter
authors.initials: P
authors.lastname: Speier
authors.forename: Ioannis
authors.initials: I
authors.lastname: Koktzoglou
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007866:Leg / Q000098:blood supply / Q000473:pathology; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D058729:Peripheral Arterial Disease / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: MR angiography; flow artifacts; non-Cartesian; peripheral arterial disease; ungated