Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Reinier Postlaan 4, 6525 CG Nijmegen, The Netherlands.
Phys Med Biol. 2013 Jul 21;58(14):4881-96. doi: 10.1088/0031-9155/58/14/4881. Epub 2013 Jun 21.
Volume conduction models can help in acquiring knowledge about the distribution of the electric field induced by transcranial magnetic stimulation. One aspect of a detailed model is an accurate description of the cortical surface geometry. Since its estimation is difficult, it is important to know how accurate the geometry has to be represented. Previous studies only looked at the differences caused by neglecting the complete boundary between cerebrospinal fluid (CSF) and grey matter (Thielscher et al 2011 NeuroImage 54 234-43, Bijsterbosch et al 2012 Med. Biol. Eng. Comput. 50 671-81), or by resizing the whole brain (Wagner et al 2008 Exp. Brain Res. 186 539-50). However, due to the high conductive properties of the CSF, it can be expected that alterations in sulcus width can already have a significant effect on the distribution of the electric field. To answer this question, the sulcus width of a highly realistic head model, based on T1-, T2- and diffusion-weighted magnetic resonance images, was altered systematically. This study shows that alterations in the sulcus width do not cause large differences in the majority of the electric field values. However, considerable overestimation of sulcus width produces an overestimation of the calculated field strength, also at locations distant from the target location.
容积传导模型有助于获取经颅磁刺激诱导的电场分布知识。详细模型的一个方面是对皮质表面几何形状的准确描述。由于其估计比较困难，因此了解几何形状需要精确到何种程度是很重要的。以前的研究仅考虑了忽略脑脊液（CSF）和灰质（Thielscher 等人，2011 年《神经影像》54 234-43；Bijsterbosch 等人，2012 年《医学与生物工程计算》50 671-81）之间完整边界或调整整个大脑（Wagner 等人，2008 年《实验性大脑研究》186 539-50）的情况下产生的差异。然而，由于 CSF 的高导电性，可以预期脑回宽度的改变已经会对电场的分布产生重大影响。为了回答这个问题，本研究系统地改变了基于 T1、T2 和弥散加权磁共振图像的高度逼真的头部模型的脑回宽度。该研究表明，脑回宽度的改变不会导致大多数电场值的差异较大。然而，脑回宽度的显著夸大也会导致计算场强的高估，即使在远离目标位置的位置也是如此。
