A noniterative method to design large-tip-angle multidimensional spatially-selective radio frequency pulses for parallel transmission
✍ Scribed by Dan Xu; Kevin F. King; Yudong Zhu; Graeme C. McKinnon; Zhi-Pei Liang
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 709 KB
- Volume
- 58
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
Recently, theoretical and experimental work has shown that parallel transmission of RF pulses can be used to shorten the duration of multidimensional spatially‐selective pulses and compensate for B~1~ field inhomogeneity. However, all the existing noniterative methods can design only excitation pulses for parallel transmission with a small flip angle (e.g., 30°, or at most 90°) and cannot design large‐tip‐angle inversion/refocusing pulses, because these methods are based on the small‐tip‐angle (STA) approximation of the Bloch equation. In this work, a method to design large‐tip‐angle multidimensional spatially‐selective pulses for parallel transmission is proposed, based on an extension of the single‐channel linear‐class large‐tip‐angle (LCLTA) theory. Design examples of 2D refocusing and inversion parallel transmit pulses and magnetization profiles from Bloch equation simulations demonstrate the strength of the proposed method. A 2D spin‐echo parallel transmission experiment on a slab phantom using a 180° refocusing pulse with an eight‐channel transmit‐only array further validates the effectiveness of the proposed method. Magn Reson Med 58:326–334, 2007. © 2007 Wiley‐Liss, Inc.