High-Resolution Maps of Magnetization Transfer with Inherent Correction for RF Inhomogeneity and T1 Relaxation Obtained from 3D FLASH MRI
High-Resolution Maps of Magnetization Transfer with Inherent Correction for RF Inhomogeneity and T1 Relaxation Obtained from 3D FLASH MRI
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DOI：
10.1002/mrm.21732
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发表时间：
2008-12-01
影响因子：
3.3
通讯作者：
Dechent, Peter
中科院分区：
文献类型：
--
作者：
Helms, Gunther;Dathe, Henning;Dechent, Peter
通过类比双激励闪光，导出了磁化传递闪光信号的经验公式，引入了一个新的半定量参数，即一个磁化转移脉冲在旋转过程中施加的百分比饱和度。这个参数是通过对逆信号进行线性变换，使用质子密度和T加权两个参考实验获得的。研究了序列参数对MT饱和度的影响。3T脑成像的8.5min方案基于非选择性矢状面3D闪光，分辨率为1.25 mm各向同性，使用部分采集技术(传统的α=25ms/4.9ms/5度或11ms/4.9ms/15度作为T-1参考)。采用12.8ms高斯MT脉冲，频率为2.2 kHz，翻转角为540度。由于脑白质、灰质和脑脊液的分布明显分离，MT饱和图在脑内显示出良好的对比度。在近似范围内(激励
empirical equation for the magnetization transfer (MT) FLASH signal is derived by analogy to dual-excitation FLASH introducing a novel semiquantitative parameter for MT, the per centage saturation imposed by one MT pulse during TR. This parameter is obtained by a linear transformation of the inverse signal, using two reference experiments of proton density and T, weighting. The influence of sequence parameters on the MT saturation was studied. An 8.5-min protocol for brain imaging a 3 T was based on nonselective sagittal 3D-FLASH at 1.25 mm isotropic resolution using partial acquisition techniques (TRITE alpha = 25ms/4.9ms/5 degrees or 11 ms/4.9ms/15 degrees for the T-1 reference). 12.8 ms Gaussian MT pulse was applied 2.2 kHz off-resonance with 540 degrees flip angle. The MT saturation maps showed an excel lent contrast in the brain due to clearly separated distributiom for white and gray matter and cerebrospinal fluid. Within the limits of the approximation (excitation