title: Quantitative velocity images from thick slab 2D phase contrast.
abstract: Thick slab two-dimensional phase contrast (2D PC) angiography provides a large amount of anatomical information in a short acquisition time. Quantitative velocity information is, however, destroyed by the necessary projection dephasing gradient. We present a 2D PC acquisition scheme which retains quantitative velocity information in a thick slab acquisition. A thick slab acquisition produces an image which is a projection through an entire vessel. Accurate velocity measurements must take into account the intravoxel phase cancellation caused by a distribution of velocities within the vessel. In addition to the description of the data acquisition scheme, we outline a method for determining the mean velocity within a vessel having a laminar flow distribution. It is shown that without the consideration for intravoxel phase cancellation, the mean velocity measurement from thick slab images overestimates the true mean velocity by 10%.
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison.
authors.forename: D M
authors.initials: DM
authors.lastname: Weber
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: F R
authors.initials: FR
authors.lastname: Korosec
authors.forename: C A
authors.initials: CA
authors.lastname: Mistretta
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D001808:Blood Vessels / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural