Dynamic shim updating: A new approach towards optimized whole brain shimming
Dynamic shim updating: A new approach towards optimized whole brain shimming
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DOI：
10.1002/mrm.1910360125
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发表时间：
1996-07-01
影响因子：
3.3
通讯作者：
Nixon, T
中科院分区：
文献类型：
--
作者：
Blamire, AM;Rothman, DL;Nixon, T
静态磁场内的两个广泛的间距轴向切片的人脑映射在五个主题后，全球匀场。这揭示了在小脑和大脑之间的前后方向上的一阶场移位，这对功能和光谱磁共振成像具有影响。描述了一种称为动态匀场更新（DSU）的新方法来补偿这些场差异，由此在多层数据采集期间以真实的时间更新匀场校正场以匹配当前成像或光谱切片，提出了一个硬件单元来演示使用一阶匀场校正的方法，该方法可以在切片采集之间实时更新，以提供每个切片的最佳匀场。使用场映射和高速MR成像（回波平面成像），这是敏感的字段不均匀性的方法的效率证明。
The static magnetic field within two widely spaced axial slices of the human brain was mapped in five subjects following global shimming. This revealed a first order field shift in the anterior-posterior direction between the cerebellum and cerebrum, which has implications for functional and spectroscopic magnetic resonance imaging, A new method is described called dynamic shim updating (DSU) to compensate for these field differences whereby the shim correction fields are updated in real time during multislice data acquisition to match the current imaging or spectroscopy slice, A hardware unit is presented to demonstrate the method using the first order shim corrections, which can be updated virtually instantaneously between slice acquisitions to give optimal shimming of each slice. The efficiency of the approach is demonstrated using field mapping and high speed MR imaging (echo-planar imaging), which are sensitive to field inhomogeneity.