Weigel Matthias, Hennig Juergen
Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg.
Z Med Phys. 2008;18(3):151-61. doi: 10.1016/j.zemedi.2008.01.008.
Turbo or fast spin echo (TSE/FSE) techniques with variable flip angles have the potential to overcome specific absorption rate (SAR) limitations. Such Hyperecho-TSE sequences allow for high resolution imaging with full signal-to-noise ratio (SNR) compared to standard TSE methods. Initially, a short overview of the two basic hyperecho schemes is given. Subsequently, the manuscript focuses on the flexible hyperecho approach "TRAPS" (smooth transitions between pseudo steady states). Basic criteria for flip angle ramp selection are illustrated. Further prerequisites to establish hyperecho methods in a clinical environment such as an automatic ramp selection are discussed. A summary of the introduced framework for contrast characterization and adaptation for conventional and Hyperecho-TSE sequences is presented Finally, recent developments in hyperecho imaging are provided
具有可变翻转角的快速自旋回波(TSE/FSE)技术有潜力克服比吸收率(SAR)限制。与标准TSE方法相比,这种超回波TSE序列能够实现具有全信噪比(SNR)的高分辨率成像。首先,对两种基本的超回波方案进行简要概述。随后,本文重点关注灵活的超回波方法“TRAPS”(伪稳态之间的平滑过渡)。阐述了翻转角斜坡选择的基本标准。讨论了在临床环境中建立超回波方法的其他先决条件,如自动斜坡选择。最后,总结了所介绍的用于传统和超回波TSE序列的对比度表征和自适应框架,并介绍了超回波成像的最新进展