Improved Bloch-Siegert based B1 mapping by reducing off-resonance shift.
Improved Bloch-Siegert based B1 mapping by reducing off-resonance shift.
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DOI：
10.1002/nbm.2920
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发表时间：
2013-09
影响因子：
2.9
通讯作者：
Duyn, Jeff
中科院分区：
文献类型：
--
作者：
Duan, Qi;van Gelderen, Peter;Duyn, Jeff
最近，基于Bloch-Siegert（BS）移位现象的MRI方法已被提出作为一种快速和精确的方式来映射射频（RF）发射场（B1+场）。对于高场MRI，该方法的标测灵敏度受到与BS辐照脉冲相关的组织加热的限制。为了减轻这一点，我们研究了降低该脉冲的非共振频率的可能性，因为理论分析表明，当照射更接近共振时，基于Bloch-Siegert的B1+映射的灵敏度可以得到大幅提高。使用优化的照射脉冲形状和梯度破碎器以最小化直接激发效应，在7 T下对人脑的体内实验证实了这种方法可提高的灵敏度。这种灵敏度的提高转化为B1+估计误差减少80%，而不会增加组织加热。
Recently, an MRI method based on the Bloch-Siegert (BS) shift phenomenon has been proposed as a fast and precise way to map the radio-frequency (RF) transmit field (B1+ field). For MRI at high field, the mapping sensitivity of this approach is limited by tissue heating associated with the BS irradiation pulse. To mitigate this, we investigated the possibility of lowering the off-resonance frequency of this pulse, as theoretical analysis indicated that the sensitivity of Bloch-Siegert based B1+ mapping can be substantially improved when irradiating closer to resonance. Using optimized irradiation pulse shape and gradient crushers to minimize direct excitation effects, in vivo experiments on human brain at 7T confirmed the improved sensitivity available with this approach. This improved sensitivity translated into an 80% reduction in B1+ estimation errors, without increasing tissue heating.
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影响因子：
--
作者：
Bloch, F;Siegert, A
通讯作者：
Siegert, A
影响因子：
3.3
作者：
Nehrke, Kay;Boernert, Peter
通讯作者：
Boernert, Peter
影响因子：
3.3
作者：
Lau, Angus Z.;Chen, Albert P.;Cunningham, Charles H.
通讯作者：
Cunningham, Charles H.
影响因子：
--
作者：
RAMSEY, NF
通讯作者：
RAMSEY, NF
影响因子：
3.3
作者：
Sturm, V. J. F.;Basse-Luesebrink, T. C.;Jakob, P. M.
通讯作者：
Jakob, P. M.