In-vivo Imaging of Magnetic Fields Induced by Transcranial Direct Current Stimulation (tDCS) in Human Brain using MRI.

Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique that applies mA currents at the scalp to modulate cortical excitability. Here, we present a novel magnetic resonance imaging (MRI) technique, which detects magnetic fields induced by tDCS currents. This technique is based on Ampere’s law and exploits the linear relationship between direct current and induced magnetic fields. Following validation on a phantom with a known path of electric current and induced magnetic field, the proposed MRI technique was applied to a human limb (to demonstrate in-vivo feasibility using simple biological tissue) and human heads (to demonstrate feasibility in standard tDCS applications). The results show that the proposed technique detects tDCS induced magnetic fields as small as a nanotesla at millimeter spatial resolution. Through measurements of magnetic fields linearly proportional to the applied tDCS current, our approach opens a new avenue for direct in-vivo visualization of tDCS target engagement.

经颅直流电刺激（tDCS）是一种新兴的非侵入性神经调节技术，它在头皮上施加毫安级电流以调节皮层兴奋性。在此，我们介绍一种新的磁共振成像（MRI）技术，该技术可检测由tDCS电流诱导的磁场。这种技术基于安培定律，并利用了直流电和诱导磁场之间的线性关系。在对具有已知电流路径和诱导磁场的体模进行验证之后，所提出的MRI技术被应用于人体肢体（以证明在简单生物组织中的体内可行性）和人体头部（以证明在标准tDCS应用中的可行性）。结果表明，所提出的技术能够在毫米空间分辨率下检测到小至纳特斯拉的tDCS诱导磁场。通过测量与所施加的tDCS电流成线性比例的磁场，我们的方法为tDCS靶点结合的体内直接可视化开辟了一条新途径。