EIS检测电极屏蔽地环宽度对成像结果的影响

Effect of electrode guard ring width on image quality in electrical impedance scanning system

目的：评估电阻抗乳腺扫描（EIS）技术中检测电极阵列周围屏蔽地环大小对系统检测性能的影响,并针对64电极阵列提出合适的地环宽度.方法：在64电极的物理模型中模拟人体乳腺组织分布,采用相同电极阵列、不同屏蔽地环宽度的检测电极,分别检测均匀背景溶液、同一体积和深度的琼脂目标体,对比测量结果.人为使用绝缘材料遮盖检测电极屏蔽地环,测量30例女性志愿者,观察地环屏蔽前后的数值变化.结果：屏蔽地环宽度越小,电场边缘效应越明显,测量数据的离散性呈以下趋势：0 mm〉2 mm〉3 mm〉5 mm〉7mm.在临床检查中,屏蔽地环的不良接触同样影响EIS成像质量.结论：电极屏蔽地环宽度大小对于EIS成像中检测性能的影响至关重要,介于5-7 mm之间的屏蔽地环宽度对于64电极阵列较为合适.

AIM： To evaluate the influence of the guard ring en- circling the electrodes array with different width on electrical impedance scanning （EIS） system and find out an appropriate width of the guard ring for 64 electrodes array. METHODS： In the phantom of 64 electrodes array designed to simulate the distribu- tion of breast tissue, we used the same electrodes array with the guard ring of different width to measure the background solution and the agar block with the same volume and deepness in the same solution, Then, we contrasted the results. We used the in- sulated material to envelope the guard ring and then checked 30 female volunteers to see if the values checked with the guard ring were different from the values checked without it. RESULTS： Narrower the guard ring was, more obvious the current -field edge effect was. The dispersion of the measured data took the fol- lowing pattern ： 0 mm 〉 2 mm 〉 3 mm 〉 5 mm 〉 7 mm. During the clinical examination, poor contacts between the skin and the guard ring also affected the quality of EIS image. CONCLUSION ： The width of the guard ring is vital to the capability of EIS imaging and the appropriate width of guard ring for 64 electrodes array is from 5 mm to 7 mm.