Investigating cardiac stimulation limits of MRI gradient coils using electromagnetic and electrophysiological simulations in human and canine body models.
Investigating cardiac stimulation limits of MRI gradient coils using electromagnetic and electrophysiological simulations in human and canine body models.
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在人体和犬体模型中使用电磁和电生理模拟研究MRI梯度线圈的心脏刺激限值。
DOI：
10.1002/mrm.28472
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发表时间：
2021-03
影响因子：
3.3
通讯作者：
Guérin B
中科院分区：
文献类型：
--
作者：
Klein V;Davids M;Schad LR;Wald LL;Guérin B
心脏刺激（CS）对梯度线圈切换速度的限制难以在人体中测量;相反，现行监管指南（IEC 60601-2-33）基于动物实验和针对简单均匀身体模型计算的电场-dB/dt转换因子。我们提出了改进这种方法，通过使用更详细的CS建模的基础上现实的身体模型和电生理模型的可兴奋的心脏纤维。我们计算电磁线圈，共面回路，和商业梯度线圈在两个人体模型和犬模型引起的电场。狗的模拟模仿先前发表的实验。我们使用基于规则的算法为心脏浦肯野和心室肌纤维网络生成逼真的纤维拓扑结构，并使用这些纤维的经验证的电动模型评估CS阈值。我们能够重现平均测量的犬CS阈值在5%以内。在所有模拟中，浦肯野纤维在心室纤维之前被刺激，因此设置有效CS阈值。对于所研究的梯度线圈，x、y和z轴的模拟CS阈值至少比国际电工委员会限值大一个数量级。我们展示了一种方法来模拟梯度感应CS使用电磁和电生理建模相结合。在等待额外确认的情况下，这些模拟可以指导MRI梯度线圈切换速度的CS限值评估。这种方法可能导致不太保守但仍然安全的操作限制，从而能够使用最大梯度幅度与最近强大梯度系统的转换速率参数空间。
Cardiac stimulation (CS) limits to gradient coil switching speed are difficult to measure in humans; instead, current regulatory guidelines (IEC 60601–2-33) are based on animal experiments and electric field–to-dB/dt conversion factors computed for a simple, homogeneous body model. We propose improvement to this methodology by using more detailed CS modeling based on realistic body models and electrophysiological models of excitable cardiac fibers. We compute electric fields induced by a solenoid, coplanar loops, and a commercial gradient coil in two human body models and a canine model. The canine simulations mimic previously published experiments. We generate realistic fiber topologies for the cardiac Purkinje and ventricular muscle fiber networks using rule-based algorithms, and evaluate CS thresholds using validated electrodynamic models of these fibers. We were able to reproduce the average measured canine CS thresholds within 5%. In all simulations, the Purkinje fibers were stimulated before the ventricular fibers, and therefore set the effective CS threshold. For the investigated gradient coil, simulated CS thresholds for the x-, y-, and z-axis were at least one order of magnitude greater than the International Electrotechnical Commission limit. We demonstrate an approach to simulate gradient-induced CS using a combination of electromagnetic and electrophysiological modeling. Pending additional validation, these simulations could guide the assessment of CS limits to MRI gradient coil switching speed. Such an approach may lead to less conservative, but still safe, operation limits, enabling the use of the maximum gradient amplitude versus slew rate parameter space of recent, powerful gradient systems.
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使用逼真的身体模型预测周围神经系统中的磁刺激阈值。
影响因子：
4.6
作者：
Davids M;Guérin B;Malzacher M;Schad LR;Wald LL
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SCHMITT, F
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通讯作者：
COLATSKY, TJ
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Irnich, Wemer
通讯作者：
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