AUTOMATIC, LOCALIZED INVIVO ADJUSTMENT OF ALL 1ST-ORDER AND 2ND-ORDER SHIM COILS
AUTOMATIC, LOCALIZED INVIVO ADJUSTMENT OF ALL 1ST-ORDER AND 2ND-ORDER SHIM COILS
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DOI：
10.1002/mrm.1910290613
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发表时间：
1993-06-01
影响因子：
3.3
通讯作者：
GRUETTER, R
中科院分区：
文献类型：
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作者：
GRUETTER, R
在一台2.1特斯拉全身系统上，描述了一种“通过沿投影映射的快速自动垫片技术”(FASTMAP)的实现。该方法在2分钟内对所有一阶(X，Y，Z)和二阶(Z2，ZX，ZY，X2-Y2，2xy)线圈进行局部调整。节省的时间是通过沿六个投影而不是从整个成像数据集映射磁场来实现的。对噪声误差传播的分析表明，在毫升体积中，当信噪比大于30时，用该方法得到的剩余线宽可以忽略不计。最初将该方法应用于人脑的C-13、P-31和H-1光谱，得到C-13(144毫升体积)的线宽约为2赫兹，P-31(36毫升体积)的线宽约为2.5赫兹，H-1(36毫升体积)的线宽约为4赫兹，线形对称且可重现。
The implementation of a ''fast, automatic shimming technique by mapping along projections'' (FASTMAP) on a 2.1-Tesla whole-body system is described. The method provides a localized adjustment of all first- (X, Y, Z) and second-order (Z2, ZX, ZY, X2-Y2, 2XY) coils in 2 min. The time savings are achieved by mapping the magnetic field along six projections rather than from whole-imaging data sets. An analysis of noise error propagation suggests that in 64-ml volumes the residual linewidths obtained with the method are negligible when the signal-to-rms-noise ratio is above 30. The initial application of the method to localized C-13, P-31, and H-1 spectroscopy of the human brain resulted in linewidths of approximately 2 Hz for C-13 (144-ml volume), approximately 2.5 Hz tor P-31 (36-ml volume) and approximately 4 Hz for H-1 (36-ml volume) with symmetric and reproducible lineshapes.