Controlling radiofrequency-induced currents in guidewires using parallel transmit.
Controlling radiofrequency-induced currents in guidewires using parallel transmit.
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DOI：
10.1002/mrm.25543
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发表时间：
2015-12
影响因子：
3.3
通讯作者：
Scott, Greig
中科院分区：
文献类型：
--
作者：
Etezadi-Amoli, Maryam;Stang, Pascal;Kerr, Adam;Pauly, John;Scott, Greig
用于介入手术的起搏器导线、神经刺激器导线和导电导线等细长导线可能耦合到MRI射频(RF)发射场，可能会导致危险的组织加热。这项工作的目的是论证使用并行传输来控制加长导体中感应射频电流的可行性，从而降低射频加热风险。在1.5T的四通道并行传输系统上进行了体模实验。利用从轴向B1+映射得到的耦合测量，设计了能够产生最小导线电流的平行传输“零模”激励。使用B1+MAP、电流传感器测量和荧光温度探头测量来评估由此产生的电流降低性能。零模激励使最大耦合模电流降低了2-80倍。对于直丝实验，施加在单一导线位置的零电流足以将尖端加热降低到可检测到的水平以下。对于较长的插入长度和弯曲的几何图形，在两个导线位置施加电流零点会导致沿导线长度的电流减少更均匀。平行传输可以用来产生激励，在细长导体中感应最小的射频电流，从而降低射频加热风险，同时仍允许可视化周围体积。
Elongated conductors, such as pacemaker leads, neurostimulator leads, and conductive guidewires used for interventional procedures, can couple to the MRI radiofrequency (RF) transmit field, potentially causing dangerous tissue heating. The purpose of this work is to demonstrate the feasibility of using parallel transmit to control induced RF currents in elongated conductors, thereby reducing the RF heating hazard. Phantom experiments were performed on a four-channel parallel transmit system at 1.5T. Parallel transmit “null mode” excitations that induce minimal wire current were designed using coupling measurements derived from axial B1+ maps. The resulting current reduction performance was evaluated with B1+ maps, current sensor measurements, and fluoroptic temperature probe measurements. Null mode excitations reduced the maximum coupling mode current by factors ranging from 2–80. For the straight wire experiment, a current null imposed at a single wire location was sufficient to reduce tip heating below detectable levels. For longer insertion lengths and a curved geometry, imposing current nulls at two wire locations resulted in more distributed current reduction along the wire length. Parallel transmit can be used to create excitations that induce minimal RF current in elongated conductors, thereby decreasing the RF heating risk, while still allowing visualization of the surrounding volume.
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影响因子：
3.3
作者：
Buehrer, Martin;Pruessmann, Klaas P.;Kozerke, Sebastian
通讯作者：
Kozerke, Sebastian
影响因子：
3.3
作者：
Overall, William R.;Pauly, John M.;Scott, Greig C.
通讯作者：
Scott, Greig C.
影响因子：
3.3
作者：
Eryaman, Yigitcan;Turk, Esra Abaci;Atalar, Ergin
通讯作者：
Atalar, Ergin
影响因子：
3.3
作者：
Nordbeck, Peter;Fidler, Florian;Quick, Harald H.
通讯作者：
Quick, Harald H.
影响因子：
6.7
作者：
Rezai, AR;Phillips, M;Shellock, FG
通讯作者：
Shellock, FG