Improving T2-Weighted Imaging at High Field Through the Use of kT-Points
Improving T2-Weighted Imaging at High Field Through the Use of kT-Points
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DOI：
10.1002/mrm.24805
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发表时间：
2014-04-01
影响因子：
3.3
通讯作者：
Marques, Jose P.
中科院分区：
文献类型：
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作者：
Eggenschwiler, Florent;O'Brien, Kieran R.;Marques, Jose P.
目的在高磁场强度（B ~ 0 3 T）下，较短的射频波长产生不均匀的发射磁场分布。这可能导致整个大脑的对比度变化，这在需要多个射频脉冲的T-2加权成像中特别明显。为了在7 T下获得全脑具有均匀对比度的T-2加权图像，将短（2-3 ms）3D定制射频脉冲（k（T）点）集成到3D可变翻转角turbo自旋回波序列中。空间分辨的扩展相位图模拟和在体内采集在7 T，利用单通道和并行传输系统，被用来测试不同的k（T）点configuration.ResultsSimulations表明，一个扩展的优化k-空间轨迹，确保整个图像更均匀的信号。在体内实验表明，高质量的T-2加权脑图像均匀的信号和对比度，在7 T通过使用所提出的methods.ConclusionThis工作表明，T-2加权图像没有伪影所造成的B-1（+）的不均匀性，可以通过优化的扩展k（T）点脉冲在高场获得。Magn Reson Med 71：1478-1488，2014。(c)2013 Wiley Periodicals，Inc.
PurposeAt high magnetic field strengths (B-0 3 T), the shorter radiofrequency wavelength produces an inhomogeneous distribution of the transmit magnetic field. This can lead to variable contrast across the brain which is particularly pronounced in T-2-weighted imaging that requires multiple radiofrequency pulses. To obtain T-2-weighted images with uniform contrast throughout the whole brain at 7 T, short (2-3 ms) 3D tailored radiofrequency pulses (k(T)-points) were integrated into a 3D variable flip angle turbo spin echo sequence.MethodsThe excitation and refocusing hard pulses of a variable flip angle turbo spin echo sequence were replaced with k(T)-point pulses. Spatially resolved extended phase graph simulations and in vivo acquisitions at 7 T, utilizing both single channel and parallel-transmit systems, were used to test different k(T)-point configurations.ResultsSimulations indicated that an extended optimized k-space trajectory ensured a more homogeneous signal throughout images. In vivo experiments showed that high quality T-2-weighted brain images with uniform signal and contrast were obtained at 7 T by using the proposed methodology.ConclusionThis work demonstrates that T-2-weighted images devoid of artifacts resulting from B-1(+) inhomogeneity can be obtained at high field through the optimization of extended k(T)-point pulses. Magn Reson Med 71:1478-1488, 2014. (c) 2013 Wiley Periodicals, Inc.