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The shape of electrodes is one of the important factors in tDCS1. The existence of corners and edges in structures of electrodes has important effects in producing of the electric field stimulation in the brain. In this paper, by designing some types of electrode structures using regular polygons and semi-fractals, the electric field distribution in all layers of the head is measured and is studied. For this aim, using FEM2, one MRI3 data from stroke patients is simulated. The results of the tDCS show the sharper corners have more effect in electric field distribution. Also, the direction of the current density is studied. The results show, if the structure of the electrodes has corners and edges so, the direction of the current density of the tDCS is not uniform.

Stroke is the principal cause of death all over the world. Lesion detection is a crucial step in diagnosis and therapy of patients with stroke lesion. MRI is useful device in lesion segmentation that produces different brain image series, such as T1, T2 and FLAIR. Nowadays, automatic methods for detecting lesion are preferable to semi-automatic methods due to their speed, flexibility and availability. So, the efficiency of these methods in detecting lesion is important. LST-Lesion segmentation tool by SPM is an automatic tool which is most commonly used to detect Multiple Sclerosis (MS) lesions. Moreover, the LST has been investigated for detecting of stroke lesions. In this study the operation of this tool is examined both in the old version (SPM8) and the new one (SPM12) in a wide range of lesion volumes of ischemic stroke. The results show that LST can be used as an automated tool for detecting of stroke lesions but it works better in old version. Also, the performance of the LST in detection of lesions is improved by two feature maps. These feature maps separate missed and abnormal pixels. These two properties have more effects in detection of large lesions which are detected with high quality.

In order to optimize the capability of transcranial Direct Current Stimulation (tDCS), electrode arrangements and the inward current stimulation are taken into account as two crucial factors. In this contribution, in order to specify the electrode positions, a detailed protocol is investigated, in which regarding the intended targeted regions, the optimal montages with an arbitrary number of electrodes are developed. After designing the positions of all active and returned electrodes, the corresponding inward current density is determined for each electrode. The outcomes of the simulation and the electric field distributions in the hand cortex prove that the proposed protocol is capable of improving the tDCS efficiency substantially in all head layers. Furthermore, in order to compare our approach with the other works found in the literature, a performance evaluation is curried out by calculating the maximum electric field distribution in the targeted region. This study shows that it improves tDCS efficiency virtually 2.5 times in comparison to High Definition (HD) montages in the gray matter and nearly 1.5 times in comparison to the other inner layers. Such an outstanding achievement in the gray matter can be regarded as an interesting standpoint in tDCS-rehabilitation studies.