Dynamic multi-coil technique (DYNAMITE) shimming for echo-planar imaging of the human brain at 7 Tesla.
Dynamic multi-coil technique (DYNAMITE) shimming for echo-planar imaging of the human brain at 7 Tesla.
复制标题
动态多型技术技术（炸药）在7特斯拉的人脑回声 - 平面成像。
DOI：
10.1016/j.neuroimage.2014.11.011
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发表时间：
2015-01-15
期刊：
影响因子：
5.7
通讯作者：
de Graaf RA
中科院分区：
文献类型：
--
作者：
Juchem C;Umesh Rudrapatna S;Nixon TW;de Graaf RA
梯度回波平面成像(EPI)是功能磁共振成像和其他依赖快速MRI成像脑激活和连接的方法的主要选择。然而，EPI对B0磁场不均匀的高度敏感性带来了严峻的挑战。传统的低次球谐(SH)函数磁场匀场能够补偿浅场失真，但对整体大脑匀场或对前额叶(PFC)等易感性较强的B0区的匀场效果较差。最近使用动态多线圈技术(炸药)在7特斯拉的人脑中展示了出色的B0均匀性，用于磁场填补(Jucem等人，J Magn Reson(2011)212：280-288)。在这里，我们报告了多层EPI和T2*映射的炸药垫片的好处。在7特斯拉时，用炸药垫片得到人脑中残留B0分布的标准偏差为13赫兹，比采用静态零至三阶SH形状的传统垫片低60%。SH垫片的残余场不均匀导致fMRI常用的采集参数平均偏移8 mm，而炸药垫片使其减少到1.5-3 mm。用炸药垫片测得的前额叶和颞叶皮质的T2*值比用SH垫片测得的T2*值长10-50%。通过炸药垫片减少混杂的宏观B0场梯度，从而保证了更好地获得相关的微观T2*效应。高空间分辨率和炸药垫片相结合，可以在很大程度上无伪影地绘制整个大脑的EPI和T2*图，包括前额叶和颞叶区域。炸药垫片有望使广泛的MRI应用受益，这些应用依赖于出色的B0磁场条件，包括基于EPI的fMRI来研究各种认知过程和评估体内大规模的大脑连接。因此，炸药垫片有可能在人类磁共振扫描仪中取代传统的SH垫片系统。
Gradient-echo echo-planar imaging (EPI) is the primary method of choice in functional MRI and other methods relying on fast MRI to image brain activation and connectivity. However, the high susceptibility of EPI towards B0 magnetic field inhomogeneity poses serious challenges. Conventional magnetic field shimming with low-order spherical harmonic (SH) functions is capable of compensating shallow field distortions, but performs poorly for global brain shimming or on specific areas with strong susceptibility-induced B0 distortions such as the prefrontal cortex (PFC). Excellent B0 homogeneity has been demonstrated recently in the human brain at 7 Tesla with the DYNAmic Multi-coIl TEchnique (DYNAMITE) for magnetic field shimming (Juchem et al., J Magn Reson (2011) 212:280-288). Here, we report the benefits of DYNAMITE shimming for multi-slice EPI and T2* mapping. A standard deviation of 13 Hz was achieved for the residual B0 distribution in the human brain at 7 Tesla with DYNAMITE shimming and was 60% lower compared to conventional shimming that employs static zero through third order SH shapes. The residual field inhomogeneity with SH shimming led to an average 8 mm shift at acquisition parameters commonly used for fMRI and was reduced to 1.5-3 mm with DYNAMITE shimming. T2* values obtained from the prefrontal and temporal cortices with DYNAMITE shimming were 10-50% longer than those measured with SH shimming. The reduction of the confounding macroscopic B0 field gradients with DYNAMITE shimming thereby promises improved access to the relevant microscopic T2* effects. The combination of high spatial resolution and DYNAMITE shimming allows largely artifact-free EPI and T2* mapping throughout the brain, including prefrontal and temporal lobe areas. DYNAMITE shimming is expected to critically benefit a wide range of MRI applications that rely on excellent B0 magnetic field conditions including EPI-based fMRI to study various cognitive processes and assessing large-scale brain connectivity in vivo. As such, DYNAMITE shimming has the potential to replace conventional SH shim systems in human MR scanners.
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影响因子：
3.3
作者：
JEZZARD, P;BALABAN, RS
通讯作者：
BALABAN, RS
影响因子：
3.3
作者：
Blamire, AM;Rothman, DL;Nixon, T
通讯作者：
Nixon, T
人类前额叶皮层与一组局部电气线圈的磁场均匀化。
影响因子：
3.3
作者：
Juchem, Christoph;Nixon, Terence W.;McIntyre, Scott;Rothman, Douglas L.;de Graaf, Robin A.
通讯作者：
de Graaf, Robin A.
影响因子：
2.2
作者：
Juchem, Christoph;Green, Dan;de Graaf, Robin A.
通讯作者：
de Graaf, Robin A.
DOI：
10.1016/j.jmr.2010.03.008
发表时间：
2010-06
期刊：
Journal of magnetic resonance (San Diego, Calif. : 1997)
影响因子：
--
作者：
Juchem C;Nixon TW;McIntyre S;Rothman DL;de Graaf RA
通讯作者：
de Graaf RA