DREAM - a novel approach for robust, ultrafast, multislice B1 mapping
DREAM - a novel approach for robust, ultrafast, multislice B1 mapping
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DOI：
10.1002/mrm.24158
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发表时间：
2012-11-01
影响因子：
3.3
通讯作者：
Boernert, Peter
中科院分区：
文献类型：
--
作者：
Nehrke, Kay;Boernert, Peter
提出了一种新的多层b1映射方法，称为双重聚焦回波采集模式，能够在1秒内覆盖整个发射线圈体积，比现有方法快一个数量级以上。双重聚焦回波采集模式技术采用受激回波采集模式（STEAM）制备序列，然后是定制的单次梯度回波序列，同时测量受激回波和自由感应衰减作为梯度召回回波，并根据两个测量信号的比值确定STEAM制备射频脉冲的实际翻转角度。由于时序方案的精心设计，该方法对磁化率/化学位移效应不敏感，并且可以免费提供B0相位图和收发器相位图。该方法仅具有较弱的T1和T2依赖性，而且只造成较低的比吸收率（SAR）负担。从理论和幻影实验两方面考察了该方法在系统误差和统计误差方面的准确性。此外，在8通道并行传输3t MRI系统上对腹部、腿部和头部进行b1定位和射频闪烁实验，验证了该方法的体内性能。《理性医学杂志》，2012。(c) 2012 Wiley期刊有限公司
A novel multislice B1-mapping method dubbed dual refocusing echo acquisition mode is proposed, able to cover the whole transmit coil volume in only one second, which is more than an order of magnitude faster than established approaches. The dual refocusing echo acquisition mode technique employs a stimulated echo acquisition mode (STEAM) preparation sequence followed by a tailored single-shot gradient echo sequence, measuring simultaneously the stimulated echo and the free induction decay as gradient-recalled echoes, and determining the actual flip angle of the STEAM preparation radiofrequency pulses from the ratio of the two measured signals. Due to an elaborated timing scheme, the method is insensitive against susceptibility/chemical shift effects and can deliver a B0 phase map and a transceive phase map for free. The approach has only a weak T1 and T2 dependence and moreover, causes only a low specific absorption rate (SAR) burden. The accuracy of the method with respect to systematic and statistical errors is investigated both, theoretically and in experiments on phantoms. In addition, the performance of the approach is demonstrated in vivo in B1-mapping and radiofrequency shimming experiments on the abdomen, the legs, and the head on an eight-channel parallel transmit 3 T MRI system. Magn Reson Med, 2012. (c) 2012 Wiley Periodicals, Inc.