title: MR angiography of the pelvis with variable velocity encoding and a phased-array coil.
abstract: OBJECTIVE
  To evaluate the feasibility of an automated variable velocity-encoding sequence and improve the signal-to-noise ratio (S/N) on magnetic resonance angiograms with use of phase contrast and a pelvic phased-array coil.
  
  
  METHODS
  Three cardiac-gated, two-dimensional (2D), phase-contrast (PC) sequences were evaluated in 10 healthy subjects. A 2D gated PC sequence with variable velocity encoding (velocity-optimized phase contrast [VOPC]) was compared with gated 2D PC sequences performed with high or low constant velocity encoding. S/Ns in VOPC images obtained with a pelvic phased-array coil were compared with those in VOPC images obtained with a body coil.
  
  
  RESULTS
  Two blinded readers preferred VOPC for simultaneous display of large and small blood vessels in one acquisition compared with constant low (P = .0105) and high (P = .0067) velocity encoding and for overall image interpretation. VOPC images obtained with the pelvic coil had a 68%-100% better S/N compared with those obtained with the body coil.
  
  
  CONCLUSIONS
  Use of a phased-array coil and variable velocity encoding improves depiction of segmental vascular anatomic structures of the pelvis.
authors.affiliation: Department of Radiology, University of Wisconsin Clinical Science Center, Madison 53792.
authors.forename: J S
authors.initials: JS
authors.lastname: Swan
authors.forename: T M
authors.initials: TM
authors.lastname: Grist
authors.forename: D M
authors.initials: DM
authors.lastname: Weber
authors.forename: I A
authors.initials: IA
authors.lastname: Sproat
authors.forename: M M
authors.initials: MM
authors.lastname: Wojtowycz
mesh_terms: D001783:Blood Flow Velocity; D001808:Blood Vessels / Q000033:anatomy & histology*; D005240:Feasibility Studies; D005263:Femoral Artery / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D007083:Iliac Artery / Q000033:anatomy & histology / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D010388:Pelvis / Q000098:blood supply*