Finite Element Modeling and Simulation of EIT Electric Field.
In one polar drive, the used boundary conditions were as follows: (1) inward current flow (current density = 15.92 A/[m.sub.2]) was applied to the outer boundary of electrode 1 to simulate the EIT driving current of 1250 [mu]A, (2) ground was applied to the outer boundary of electrode 9, and (3) all other external boundaries were treated as insulated.
For example, a circular region was set at the midpoint of line O-e13 of the model, with a conductivity of 0.65 S/m  and a radius of 2 cm, to simulate a hemorrhagic stroke lesion (Figure 6(a)); one frame of EIT raw data was then calculated.
One frame of EIT raw data was obtained in every lesion setting.
A frame of EIT raw data was obtained after each lesion was set.
An EIT system named FMEIT-5  was used to measure EIT data.
We first collected data on the physical phantom without agar using EIT for 1 h.
Next we put agar cylinders into the physical phantom (the location and size of each agar are shown in the next section) and measured EIT data, as shown in Figure 10.
When the simulated cerebral hemorrhage lesion gradually decreased (Figures 7(a)-7(f)), the [IA.sub.max] of EIT data from the two hemispheres of the model was gradually reduced (Figure 13); the area of reconstructed object in the SEIT image was also gradually reduced (Figures 14(a)-14(f)).
When the simulated cerebral ischemia lesion gradually decreased (Figures 7(a)-7(f)), the [IA.sub.max] of EIT data from the two hemispheres of the model gradually reduced (Figure 16); the area of the reconstructed object in the SEIT image also gradually reduced (Figures 17(a)-17(f)).
The significance of this study is that it proposes a novel EIT approach that reconstructs the image of a unilateral cerebral lesion based on one frame of EIT data to provide information on the lesion.
They maybe detected by SEIT in the future by optimizing the performances of the EIT imaging algorithm and the hardware system.