Mitigation of susceptibility-induced signal loss in neuroimaging using localized shim coils
Mitigation of susceptibility-induced signal loss in neuroimaging using localized shim coils
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DOI：
10.1002/mrm.20365
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发表时间：
2005-02-01
影响因子：
3.3
通讯作者：
Glover, GH
中科院分区：
文献类型：
--
作者：
Hsu, JJ;Glover, GH
磁场畸变的校正对于获得准确的脑血氧水平依赖性功能磁共振成像（fMRI）激活图至关重要。目前的工作介绍了一种主动匀场方法，利用电阻匀场线圈放置在口腔中产生的磁场，局部均匀化的磁场在额叶的下部，该领域是最严重的扭曲。对于扫描仪操作员选择的感兴趣区域，可以逐个患者地原位优化匀场场。在1.5 T的方法被证明是有效的，在减少场的不均匀性和恢复的fMRI信号。例如，在大约149 cm（3）的感兴趣区域中，简单几何形状的线圈可以将磁场的均方根降低50%以上，并且恢复的信号增加了屏气fMRI实验中检测到的激活程度。(C)2005 Wiley-Liss，Inc.
Correction of magnetic field distortions is essential for obtaining accurate brain blood-oxygen-level-dependent functional magnetic resonance imaging (fMRI) activation maps. The present work introduces an active shimming method that utilizes the magnetic field generated by resistive shim coils placed in the mouth to locally homogenize the magnetic field in the inferior portion of the frontal lobe, where the field is most seriously distorted. The shimming field can be optimized in situ patient by patient for the region of interest of the scanner operator's choice. The method at 1.5 T is shown to be effective in reducing field inhomogeneity and in recovery of fMRI signal. For example, in a region of interest approximately of 149 cm(3), a coil of simple geometry can reduce the root mean square of the magnetic field by more than 50% and the recovered signal increases the extent of activation detected in a breath-holding fMRI experiment. (C) 2005 Wiley-Liss, Inc.