High-field MRS of the human brain at short TE and TR
High-field MRS of the human brain at short TE and TR
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DOI：
10.1002/nbm.1660
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发表时间：
2011-11-01
影响因子：
2.9
通讯作者：
Klomp, Dennis W. J.
中科院分区：
文献类型：
--
作者：
Boer, Vincent O.;Siero, Jeroen C. W.;Klomp, Dennis W. J.
在体内MRS的人脑在7特斯拉允许识别大量的代谢物在更高的空间分辨率比目前可能在较低的场强。然而，在7特斯拉的临床可行的扫描时间内，在高空间分辨率下的MRS中的体内定位和伪影抑制中的几个挑战是复杂的。已发表的7特斯拉MRS序列由于过多的射频（RF）功率沉积而遭受长回波时间、固有信噪比（SNR）损失、大化学位移伪影或长重复时间。在本研究中，使用了脉冲采集序列，该序列不受这些高场缺点的影响。使用切片选择性激发结合用于平面内定位的高分辨率化学位移成像来限制化学位移伪影。脉冲采集方法导致非常短的回波时间为1.4 ms。开发了成本函数引导匀场算法来约束激励切片中的频率偏移，因此可以采用绝热频率选择性抑制来最大限度地减少激励切片中高强度脂质和水信号的伪影。在TR为1 s时的高灵敏度在室上切片上以及在非常接近颅骨的额叶皮层区域中均得到证明，标称空间分辨率为0.25 cc，在可行的扫描时间内。版权所有（C）2011约翰威利父子有限公司
In vivo MRS of the human brain at 7 tesla allows identification of a large number of metabolites at higher spatial resolutions than currently possible at lower field strengths. However, several challenges complicate in vivo localization and artifact suppression in MRS at high spatial resolution within a clinically feasible scan time at 7 tesla. Published MRS sequences at 7 tesla suffer from long echo times, inherent signal-to-noise ratio (SNR) loss, large chemical shift displacement artifacts or long repetition times because of excessive radiofrequency (RF) power deposition. In the present study a pulse-acquire sequence was used that does not suffer from these high field drawbacks. A slice selective excitation combined with high resolution chemical shift imaging for in-plane localization was used to limit chemical shift displacement artifacts. The pulse-acquire approach resulted in a very short echo time of 1.4 ms. A cost function guided shimming algorithm was developed to constrain frequency offsets in the excited slice, therefore adiabatic frequency selective suppression could be employed to minimize artifacts from high intensity lipids and water signals in the excited slice. The high sensitivity at a TR of 1 s was demonstrated both on a supraventricular slice as well as in an area very close to the skull in the frontal cortex at a nominal spatial resolution of 0.25 cc within a feasible scan time. Copyright (C) 2011 John Wiley & Sons, Ltd.