Mapping the velocity vector onto the spin vector: Two-dimensional velocity-selective spin excitation for MR flow imaging

✍ Scribed by Han Wen

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 277 KB
• Volume: 46
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1255

✦ Synopsis

Abstract

This article presents a two‐dimensional velocity‐selective spin excitation (2D‐VSP) method that enables quantitative imaging of motion in two directions in a single scan, without the need for image subtraction or combination. It is based on the idea of mapping a 2D velocity vector directly onto the transverse magnetization vector, such that the signal intensity reflects the speed of motion, while the signal phase represents the direction of motion. Experimental demonstration is presented in conjunction with an analysis of the accuracy of this method. VSP methods are often limited by inconsistent static signal suppression under variable shim and RF conditions. By using adiabatic RF pulses in a 2D‐VSP composite that possesses time‐reversal symmetry, consistent background suppression of 30‐fold or higher was demonstrated over experimental conditions of ±200 Hz off‐resonance and 30% RF field variation. Magn Reson Med 46:767–772, 2001. © 2001 Wiley‐Liss, Inc.