Guadagnin Vanessa, Parazzini Marta, Fiocchi Serena, Liorni Ilaria, Ravazzani Paolo
IEEE Trans Biomed Eng. 2016 Jul;63(7):1543-50. doi: 10.1109/TBME.2015.2498646. Epub 2015 Nov 6.
Deep transcranial magnetic stimulation (dTMS) has been recently used in several clinical studies as diagnostic and therapeutic tool. However, electric field (E) distributions induced in the brain by dTMS are still unknown. This paper provides a characterization of the induced E distributions in the brain of a realistic human model due to 16 different coil configurations.
The scalar potential finite-element method was used to calculate the E distributions differentiating the brain structures, e.g., cortex, white matter, anterior cingulated cortex, cerebellum, thalamus, hypothalamus, nucleus accumbens, amygdale, and hippocampus.
Our results support that the double cone coils and the large diameter circular coils are more prone to activate deeper brain structures but are also characterized by a reduced focality on the surface of the cortex, with the consequent possible counter effect of stimulating regions not of interest. The Hesed coils, although their ability to reach deep brain tissues is lower, seem to be more able to reduce the effect on other brain regions where the stimulation is undesired.
All the coil configurations resulted subjected to a depth-focality tradeoff.
Since there is not a configuration that is capable of achieving a stimulation both deep and focal, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between these two different needs.
深部经颅磁刺激（dTMS）最近已在多项临床研究中用作诊断和治疗工具。然而，dTMS在大脑中诱发的电场（E）分布仍然未知。本文给出了由于16种不同线圈配置在真实人体模型大脑中诱发的E分布特征。
使用标量势有限元法计算区分大脑结构（如皮质、白质、前扣带回皮质、小脑、丘脑、下丘脑、伏隔核、杏仁核和海马体）的E分布。
我们的结果表明，双锥线圈和大直径圆形线圈更容易激活更深层的脑结构，但在皮质表面的聚焦性也较低，从而可能对非目标刺激区域产生反作用。赫塞德线圈虽然到达深层脑组织的能力较低，但似乎更能减少对其他不需要刺激的脑区的影响。
所有线圈配置都存在深度-聚焦性权衡。
由于不存在能够实现深部和聚焦刺激的配置，因此为特定临床应用选择最合适的线圈设置应基于对这两种不同需求的平衡评估。
