Multicoil Shimming of the Mouse Brain
Multicoil Shimming of the Mouse Brain
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DOI：
10.1002/mrm.22850
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发表时间：
2011-09-01
影响因子：
3.3
通讯作者：
de Graaf, Robin A.
中科院分区：
文献类型：
--
作者：
Juchem, Christoph;Brown, Peter B.;de Graaf, Robin A.
磁共振成像和光谱学允许对大脑功能和生理进行非侵入性测量，但需要良好的磁场均匀度才能获得有意义的结果。小鼠大脑中磁场分布的均匀化(即垫片)是一项困难的任务，因为复杂的磁化率感应场扭曲与物体的小尺寸相结合。到目前为止，在小鼠身上实现令人满意的全脑垫片仍然是一个重大挑战。一组48个圆形线圈(直径13 mm)以直径32 mm的圆柱形图案排列，并以+/-1A的单个动态电流范围驱动，所产生的磁场被证明能够显著减少在9.4特斯拉时在小鼠大脑中遇到的场扭曲。静态多线圈垫场使Larmor频率的标准偏差与二阶球面谐波垫场相比降低了31%，通过动态方法特定于切片的多线圈垫场实现了66%的窄化。对于梯度回波成像，多线圈垫片最大限度地减少了脑部外围与垫片相关的信号空洞，与球面谐波垫片相比，总体信号增益最高可达51%。Magn Reson Med 66：893-900,2011。(C)2011年Wiley-Liss，Inc.
MR imaging and spectroscopy allow the noninvasive measurement of brain function and physiology, but excellent magnetic field homogeneity is required for meaningful results. The homogenization of the magnetic field distribution in the mouse brain (i.e., shimming) is a difficult task due to complex susceptibility-induced field distortions combined with the small size of the object. To date, the achievement of satisfactory whole brain shimming in the mouse remains a major challenge. The magnetic fields generated by a set of 48 circular coils (diameter 13 mm) that were arranged in a cylinder-shaped pattern of 32 mm diameter and driven with individual dynamic current ranges of +/- 1 A are shown to be capable of substantially reducing the field distortions encountered in the mouse brain at 9.4 Tesla. Static multicoil shim fields allowed the reduction of the standard deviation of Larmor frequencies by 31% compared to second order spherical harmonics shimming and a 66% narrowing was achieved with the slice-specific application of the multicoil shimming with a dynamic approach. For gradient echo imaging, multicoil shimming minimized shim-related signal voids in the brain periphery and allowed overall signal gains of up to 51% compared to spherical harmonics shimming. Magn Reson Med 66:893-900, 2011. (C) 2011 Wiley-Liss, Inc.