Departamento Ingeniería de Sistemas y Electrónica, Avenida de la Universidad, 10, E-11519, Puerto Real (Cádiz), Spain. Author to whom any correspondence should be addressed.
J Neural Eng. 2020 Feb 12;17(1):016056. doi: 10.1088/1741-2552/ab4ba2.
Interleaving TMS (transcranial magnetic stimulation) with fMRI (functional Magnetic Resonance Imaging) is a promising technique to study functional connectivity in the human brain, but its development is being restricted by technical limitations, such as that due to the interaction of the TMS current pulses with the magnetic fields of an MRI scanner. In this work, a TMS coil design method capable of controlling Lorentz forces experienced by the coil in the presence of static magnetic fields is presented.
The suggested approach is based on an existing inverse boundary element method (IBEM) for TMS coil design, in which new electromagnetic computational models of the Lorentz forces have been included to be controlled in the design process.
To demonstrate the validity of this technique, it has been used for the design and simulation of TMS coils wound on rectangular flat, spherical and hemispherical surfaces with improved mechanical stability. The obtained results confirm that TMS coils with reduced Lorentz forces inside the static main field of an MRI scanner can be produced, which is achieved to the detriment of other coil performance parameters.
The proposed approach provides an efficient tool to design TMS stimulators of a wide range of coil geometries with improved mechanical stability, which can be extremely useful to overcome current limitations for interleaved TMS-fMRI.
在 fMRI（功能性磁共振成像）中加入 TMS（经颅磁刺激）是一种很有前途的研究人类大脑功能连接的技术，但由于 TMS 电流脉冲与 MRI 扫描仪磁场的相互作用等技术限制，其发展受到限制。在这项工作中，提出了一种能够控制线圈在静磁场中所受洛伦兹力的 TMS 线圈设计方法。
所提出的方法基于现有的 TMS 线圈设计逆边界元方法（IBEM），其中在设计过程中包括了新的电磁计算洛伦兹力模型以进行控制。
为了验证该技术的有效性，已将其用于在 MRI 扫描仪静磁场中具有改进机械稳定性的矩形平面、球形和半球形表面上绕制 TMS 线圈的设计和模拟。所得到的结果证实，可以产生在 MRI 扫描仪静磁场内部减小洛伦兹力的 TMS 线圈，这是以牺牲其他线圈性能参数为代价实现的。
所提出的方法为设计具有改进机械稳定性的各种线圈几何形状的 TMS 刺激器提供了一种有效的工具，这对于克服当前的交错 TMS-fMRI 限制非常有用。
