Velocity-selective excitation: Principles and applications.

Publication Type	Review
Authors	Zun Z, Shin T
Journal	NMR Biomed
Volume	36
Issue	2
Pagination	e4820
Date Published	09/09/2022
ISSN	1099-1492
Keywords	Magnetic Resonance Angiography, Arteries
Abstract	Velocity-selective (VS) excitation is a relatively new type of excitation that can be useful for generating image contrast based on spin's motion. This review aims to explain the principles of VS excitation and their utilization for clinical applications. We first review the generalized excitation k-space formalism, which reveals a Fourier relationship between sequence parameters and excitation profiles for spins with arbitrary spatial location, off-resonance, and velocity. Based on the k-space framework, we analyze practical VS excitation pulse sequences that yield sinusoidal or sinc-shaped velocity profiles. Then we demonstrate how these two types of VS excitation can be used as magnetization preparation for clinical applications, including saturation- or inversion-based arterial spin labeling and black- or bright-blood angiography. We also discuss practical considerations and issues for each application, including the determination of design parameters and the effects of MR system errors, such as magnetic field offsets and eddy currents.
DOI	10.1002/nbm.4820
PubMed ID	35994473
PubMed Central ID	PMC9845137