Controlled E-field gradient coils
Controlled E-field gradient coils
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DOI：
10.1007/s10334-003-0015-7
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发表时间：
2003-11-01
影响因子：
2.3
通讯作者：
Haywood, B
中科院分区：
文献类型：
--
作者：
Mansfield, P;Bowley, RM;Haywood, B
外周神经刺激是当前梯度线圈设计中的主要问题。患者的感应电流问题与梯度强度和调制频率直接相关。梯度线圈的当前设计倾向于限制超高速成像方法，例如通过产生刺痛感和不自主肌肉抽搐的感应电流的效应的回波平面成像！神经刺激也可能引发癫痫发作和/或心脏纤颤。为了减少感应电流，一个重要的方面是线圈的几何形状。期望以防止身体内的闭环循环电流的方式设计梯度线圈。使用具有矩形几何形状的四扇区梯度线圈，在低互耦合模式下操作的初步结果表明线圈的受试者体积内的电场显著减小。患者体内感应电流的减少允许在更高的磁场强度下更安全地操作，以及目前通过标准线圈几何形状中的神经刺激效应禁止的更快扫描。
Peripheral neural stimulation is a major problem in current gradient coil designs. Induced current problems in patients relate directly to gradient strength and modulation frequency. Current designs of gradient coil tend to limit ultra-high-speed imaging methods such as echo-planar imaging through the effect of induced currents which produce tingling sensations and involuntary muscle twitch! Neural stimulation could also trigger epileptic fits and/or cardiac fibrillation. For reduction of induced currents, an important aspect is the coil geometry. It is desirable to design the gradient coil in such a way as to prevent closed loop circulating currents within the body. Preliminary results using a four-sector gradient coil with rectangular geometry, operating in a low mutual coupling mode, indicate significant reduction in the E-field within the subject volume of the coil. Reduction in induced currents in the patient allows safer operation at higher magnetic field strengths together with faster scans currently prohibited through neural stimulation effects in standard coil geometries.