Dispersion in magnetization transfer contrast at a given specific absorption rate due to variations of RF pulse parameters in the magnetization transfer preparation
Dispersion in magnetization transfer contrast at a given specific absorption rate due to variations of RF pulse parameters in the magnetization transfer preparation
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DOI：
10.1002/mrm.1910370622
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发表时间：
1997-06-01
影响因子：
3.3
通讯作者：
Mistretta, CA
中科院分区：
文献类型：
--
作者：
Wang, Y;Grist, TM;Mistretta, CA
利用磁化制备的分段快速梯度回波序列研究了射频脉冲参数对磁化传递对比度（MTC）的影响，发现MTC不是由比吸收率（SAR）唯一决定的，射频脉冲参数（射频幅度、射频脉冲数和射频持续时间）也会影响MTC。对于70 kg的受试者，由于SAR = 1 W/kg时的RF参数差异，MTC可能存在40%的变化。增加RF脉冲的数量是比增加RF幅度更有效的增加MTC的方式。这种现象可能是由自由质子池和受限质子池之间的磁化转移的时间尺度与Mi脉冲的持续时间相同或更长的事实引起的。通过增加MT脉冲中的RF脉冲的数量来增加MT脉冲持续时间允许更有效的磁化转移，这种信息可以用作选择磁化转移（MT）脉冲的RF脉冲参数的指南。在该指南下设计的用于冠状动脉MR血管造影的非共振MT脉冲改善了远端血管的描绘。
The effects of RF pulse parameters on magnetization transfer contrast (MTC) were investigated using a magnetization prepared segmented fast gradient echo sequence, MTC was found not to be uniquely determined by the specific absorption rate (SAR), RF pulse parameters (RF amplitude, number of RF pulses and RF duration) also affect MTC. There can he 40% variation in MTC due to differences in RF parameters at SAR = 1 W/kg for a 70-kg subject. Increasing the number of RF pulses is a more efficient way to increase MTC than increasing RF amplitude, This phenomenon is likely caused by the fact that the time scale for magnetization transfer between the free and restricted proton pools is on the same order or longer than the duration of the Mi pulse, Accordingly, increase in the MT pulse duration by increasing the number of RF pulses in the MT pulse allows more effective magnetization transfer, Such information can be used as a guide to select RF pulse parameters for a magnetization transfer (MT) pulse, An off-resonance MT pulse designed under this guide for coronary MR angiography improved the depiction of distal vessels.