ASL Europe, GE Healthcare, Munich, Germany.
Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, United Kingdom.
Magn Reson Med. 2019 Jan;81(1):57-68. doi: 10.1002/mrm.27440. Epub 2018 Aug 14.
To introduce a novel MR pulse sequence, termed Looping Star, for fast, robust, and yet quiet, 3D radial multi-gradient echo T2* MR imaging.
The Looping Star pulse sequence is based on the 3D radial Rotating Ultra-Fast Imaging Sequence (RUFIS) extended by a time-multiplexed gradient-refocusing mechanism. First, multiple magnetic coherences are excited, which are subsequently gradient-refocused in form of a looping k-space trajectory. Accordingly, Looping Star captures an initial FID image followed by gradient echo images at equidistant echo times.
Looping Star was demonstrated in phantom and in vivo volunteer experiments for 3D, high resolution T2* weighted imaging, T2* mapping, and quantitative susceptibility mapping (QSM). The method is fast, quiet, and robust against imperfections including Eddy currents, motion, and geometric distortions. When applied to a motor task fMRI experiment a BOLD sensitivity of 5% was achieved at minimal acoustic noise (i.e. 2.7 dB(A) above ambient noise) and with images congruent to other anatomical scans.
Looping Star imaging provides new and exciting opportunities for fast, robust and yet quiet T2* MR imaging. Potential applications include T2*-weighted imaging, T2* mapping, QSM, and fMRI.
介绍一种新的磁共振脉冲序列，称为“Loop Star”，用于快速、稳健且安静的三维径向多梯度回波 T2*磁共振成像。
Loop Star 脉冲序列基于三维径向旋转超快成像序列（RUFIS）扩展，采用时分复用梯度重聚焦机制。首先，激发多个磁共振相干，随后以环形 k 空间轨迹的形式进行梯度重聚焦。因此，Loop Star 首先采集初始 FID 图像，然后在等时间间隔采集梯度回波图像。
Loop Star 在体模和志愿者体内实验中进行了三维、高分辨率 T2加权成像、T2映射和定量磁化率映射（QSM）的演示。该方法快速、安静且稳健，可抵抗包括涡流、运动和几何变形在内的各种不完美因素的影响。在一项运动任务 fMRI 实验中，该方法在最小的声噪声（即在环境噪声基础上增加 2.7dB(A)）下实现了 5%的 BOLD 灵敏度，并且图像与其他解剖扫描一致。
Loop Star 成像为快速、稳健且安静的 T2磁共振成像提供了新的令人兴奋的机会。潜在的应用包括 T2加权成像、T2*映射、QSM 和 fMRI。
