An in vivo comparison of the DREAM sequence with current RF shim technology
An in vivo comparison of the DREAM sequence with current RF shim technology
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DOI：
10.1007/s10334-014-0454-3
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发表时间：
2015-04-01
影响因子：
2.3
通讯作者：
Boernert, Peter
中科院分区：
文献类型：
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作者：
Nehrke, Kay;Sprinkart, Alois M.;Boernert, Peter
目的评价双重聚焦回波采集模式（dual refocusing echo acquisition mode，DREAM）B-1（+）标测序列在3 T下腹部射频匀场的性能，并与现有的射频匀场技术进行对比。对于每个志愿者，使用三种不同的B-1（+）作图技术[DREAM，实际翻转角成像（AFI）和饱和双角度方法（SDAM）]用于肝脏的RF匀场，并随后根据所实现的B-1（+）均匀性和平均B-1（+）的准确性来评估所获得的RF匀场设置的质量。校准导致平均均匀性改善39.1%（AFI = 38.7%，SDAM = 38.1%），平均B-1（+）为规定B-1（+）的90.9%（AFI = 88.9%，SDAM = 92.0%）。B-1（+）校准扫描的持续时间从30 s（AFI）和15 s（SDAM）减少到2.5 s（DREAM）。结论DREAM在不影响射频匀场性能的情况下，将肝脏的射频匀场加速了一个数量级。
Object In the present study the performance of the dual refocusing echo acquisition mode (DREAM) B-1(+) mapping sequence is evaluated for RF shimming in the abdomen at 3 T and validated against existing RF shim technology.Materials and methods In vivo experiments were performed on 19 normal volunteers using a clinical 3 T dual channel MRI system. For each volunteer three different B-1(+) mapping techniques [DREAM, actual flip angle imaging (AFI) and saturated double angle method (SDAM)] were employed for RF shimming of the liver and to subsequently assess the quality of the obtained RF shim settings in terms of the achieved B-1(+) homogeneity and accuracy of the mean B-1(+).Results DREAM-based B-1(+) calibration led to an average homogeneity improvement of 39.1 % (AFI = 38.7 %, SDAM = 38.1 %) and a mean B-1(+) of 90.9 % of the prescribed B-1(+) (AFI = 88.9 %, SDAM = 92.0 %). The duration of the B-1(+) calibration scan was reduced from 30 s (AFI) and 15 s (SDAM) to 2.5 s (DREAM).Conclusion DREAM accelerates RF shimming of the liver by an order of magnitude without compromising RF shimming performance.