title: Breath-hold three-dimensional true-FISP imaging of coronary arteries using asymmetric sampling.
abstract: OBJECTIVE
  To evaluate the feasibility of using asymmetric sampling in a three-dimensional, magnetization-prepared, segmented true-FISP (fast imaging with steady-state precession) sequence in order to reduce the sensitivity to resonance offsets, while simultaneously improving imaging speed.
  
  
  METHODS
  Asymmetric sampling reduces the repetition time, leading to reduced resonance offset effects and improved resolution in a fixed imaging time. However, it introduces additional phase terms due to blood flow, which can cause image artifacts. Computer simulations were performed to study the off-resonance and flow effects of asymmetric sampling in true-FISP. Coronary artery imaging was performed in healthy volunteers.
  
  
  RESULTS
  Simulations and volunteer studies show that image artifacts due to flow-induced phase variations may be acceptable at low velocities. Volunteer studies demonstrate that relatively high-resolution coronary artery images can then be acquired within a single breath-hold with segmented three-dimensional true-FISP imaging using data asymmetry in the readout direction.
  
  
  CONCLUSIONS
  Asymmetric sampling is a useful modification to true-FISP for reducing the off-resonance artifacts and improving imaging speed when the flow velocities are small.
authors.affiliation: Department of Radiology, Northwestern University, Chicago, Illinois, USA.
authors.forename: Vibhas S
authors.initials: VS
authors.lastname: Deshpande
authors.forename: Steven M
authors.initials: SM
authors.lastname: Shea
authors.forename: Yiu Cho
authors.initials: YC
authors.lastname: Chung
authors.forename: Richard M
authors.initials: RM
authors.lastname: McCarthy
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
mesh_terms: D000328:Adult; D003198:Computer Simulation; D003331:Coronary Vessels; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged