In vivo measurement of the brain and skull resistivities using an EIT-based method and realistic models for the head
In vivo measurement of the brain and skull resistivities using an EIT-based method and realistic models for the head
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DOI：
10.1109/tbme.2003.812164
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发表时间：
2003-06-01
影响因子：
4.6
通讯作者：
da Silva, FL
中科院分区：
文献类型：
--
作者：
Gonçalves, SI;de Munck, JC;da Silva, FL
使用基于电阻抗断层成像（EIT）的方法和头部的真实模型，对六个受试者进行了颅骨（rho（颅骨））和大脑（rho（大脑））的等效渗透率的体内测量。用于EIT的公式化是非常耗时的。然而，谢尔曼-莫里森公式的应用。将计算时间减少了5倍。在边界元模型中使用最佳点分布来优化其精度，减少数值原点的系统误差是重要的，因为成本函数是浅的。结果表明，rho（头骨）/rho（大脑）更可能在20和50之间，而不是等于普遍接受的值，（.）80. rho（大脑）的变化（平均值= 301 Ω（.）cm，SD = 13%）和rho（颅骨）（平均值= 12230 Ω（.）cm，SD = 18%）的结果相比，减少了一半，当使用球模型的结果，表明几何误差的校正是必不可少的，以获得现实的估计。然而，在对应于不同受试者的rho（颅骨）/rho（脑）值之间可能仍然存在2.4的因子。早期的结果表明，校准rho（大脑）和rho（头骨）的必要性，通过测量他们在体内，为每个主题，以减少与脑电图逆问题的错误。我们表明，所提出的方法是适合这个目标。
In vivo measurements of equivalent resistivities of skull (rho(skull)) and brain (rho(brain)) are performed for six subjects,using an electric impedance tomography (EIT)-based method and realistic models for the head.The classical boundary element method (BEM). formulation for EIT is very time consuming. However, the application of the Sherman-Morrison formula. reduces the computation time by a factor of 5. Using an optimal point distribution in the BEM model to optimize its accuracy, decreasing systematic errors of numerical origins is important because cost functions are shallow. Results demonstrate that rho(skull)/rho(brain) is more likely to be within 20 and 50 rather than equal to the commonly accepted value of, (.)80. The variation in rho(brain)(average = 301 Omega (.) cm, SD = 13%) and rho(skull)(average = 12230 Omega (.) cm, SD = 18%) is decreased by half, when compared with the results using the sphere model, showing that the correction for geometry errors is essential to obtain realistic estimations. However, a factor of 2.4 may stil exist between values of rho(skull)/rho(brain) corresponding to different subjects. Earlier results show the necessity of calibrating rho(brain) and rho(skull) by measuring them in vivo-for each subject, in order to decrease errors associated with the electroencephalogram inverse problem. We show that the proposed method is suited to this goal.