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无校准的GRAPE pTx脉冲用于7T时均的空间选择性激发
Daniel Löwen1, Eberhard D Pracht1, Marten Veldmann1
1MR Physics, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
新的通用GRAPE脉冲为MRI提供了改进的空间选择. 这些光谱选择性脉冲增强了信号噪声比和强度,推进了7TMRI技术.
科学领域:
- 磁共振成像 (MRI) 是一种磁共振成像技术.
- 无线电频率 (RF) 脉冲设计
- 高场磁共振成像 (MRI) 是一种高场磁共振成像.
背景情况:
- 渐变重定焦回声获取 (GRASE) 脉冲对于MRI至关重要.
- 为光谱选择性和空间定位优化射频脉冲是一个持续的挑战.
- 现有的方法可能在同质性,信号噪声比 (SNR) 和稳定性方面存在局限性.
研究的目的:
- 扩展通用脉冲GRAPE (梯度重定焦回声获取) 形式主义,以纳入定义的光谱响应.
- 应用这种扩展形式主义来实现MRI中的空间选择.
- 为了评估这些光谱选择性,空间选择性GRAPE脉冲的性能.
主要方法:
- 通过结合多个频率的布洛赫模拟,开发了通用光谱选择性GRAPE脉冲.
- 通过在脉冲计算过程中叠加一个恒定的梯度场来实现空间选择.
- 在切片和板块选择性成像实验中测试了开发的脉冲.
主要成果:
- 全球空间选择性GRAPE脉冲显示出改善的翻转角度 (FA) 同质性和SNR.
- 与传统的射频脉冲相比,在2D梯度回声中实现了大约6%的SNR增加.
- 与k-T-spoke脉冲相比,板选择性TSE序列的SNR增加了29%.
- 平板选择性GRAPE脉冲显示出对B0场偏差的强度增加,并且比k-T-spoke脉冲更短.
结论:
- 在关键的成像指标上,空间选择性的通用GRAPE脉冲在关键的成像指标上优于传统的k-T-spoke脉冲.
- 这些新型脉冲是短的,坚固的,并且具有光谱选择性,提供了显著的优势.
- 开发的脉冲有可能增强各种MRI应用,并加速7TMRI的临床采用.
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