title: Quantitative evaluation of nonrepetitive phase-encoding orders for first-pass, 3D contrast-enhanced MR angiography.
abstract: In this work, a detailed quantitative comparison was made of many alternative phase-encoding strategies for first-pass 3D MR angiography where each phase encode is only sampled once during the transient passage of contrast agent. A series of standard sequential and centric phase-encoding orders including elliptical centric were tested, as well as a new order called elliptical sequential. The characteristics of the different phase-encoding orders were tested using a computer simulation followed by experimental verification using a variable flip angle scheme. The characteristics to be considered included: arterial intensity, arterial-to-venous contrast, degree of artifact, and the blurring of the point-spread function. By making use of a wide range of start times and a rapidly varying contrast curve, the quantitative results clearly indicate the widely varying merits of each phase-encoding order. In general, when an optimal start time is used techniques that sample the low k-space views most compactly will produce the best results; however, the same methods are more problematic when the bolus arrival time deviates substantially from that expected.
authors.affiliation: Department of Biomedical Engineering, Faculty of Medicine, University of Alberta, Edmonton, Canada. alan.wilman@ualberta.ca
authors.forename: A H
authors.initials: AH
authors.lastname: Wilman
authors.forename: T C
authors.initials: TC
authors.lastname: Yep
authors.forename: O
authors.initials: O
authors.lastname: Al-Kwifi
mesh_terms: D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D019047:Phantoms, Imaging
chemical_list: D003287:Contrast Media