Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:1-4. doi: 10.1109/EMBC48229.2022.9871065.
Cancer recurrence is an important issue in bladder tumor resections, because tissue cannot generously be removed from the thin bladder wall without impacting its functionality. Electrical impedance measurements during an operation aim to support the surgeon in making the decision which tissue areas to preserve, because physiological changes in tissue due to cancerous mutations can be detected by their altered electrical characteristics. This work investigates the detection limits of tetrapolar sensors when the impedance of heterogeneous tissue is measured. To do this, a finite element analysis is carried out where the sensors are placed on a dielectric medium with inclusions of different sizes, conductivity, and locations relative to the sensor. It is shown that a sensor with four electrodes in a square performs poorly in comparison to a sensor where the electrodes are symmetrically shaped as rings around one center electrode. This is mainly due to its enlarged regions of negative sensitivity. Based on the results, a third, optimized sensor geometry is proposed that shows superior performance to the other sensors in terms of geometry factor, sensitivities, and tumor detection. In simulation, it can reliably detect tumors with only half the radius of the sensor surface. Smaller tumor fractions cannot be detected by either sensor.
癌症复发是膀胱肿瘤切除术中的一个重要问题，因为如果不影响膀胱壁的功能，就不能从薄的膀胱壁上大量切除组织。手术过程中的电阻抗测量旨在帮助外科医生做出决策，以保留哪些组织区域，因为由于癌症突变导致的组织生理变化可以通过其改变的电特性来检测。这项工作研究了在测量不均匀组织的阻抗时，四极传感器的检测极限。为此，进行了有限元分析，其中传感器放置在具有不同尺寸、电导率和相对于传感器位置的包含物的介电介质上。结果表明，与电极对称地形成围绕一个中心电极的环的传感器相比，具有四个电极的正方形传感器的性能较差。这主要是由于其负灵敏度区域的扩大。基于这些结果，提出了第三种优化的传感器几何形状，它在几何因子、灵敏度和肿瘤检测方面的性能优于其他传感器。在模拟中，它可以可靠地检测到只有传感器表面半径一半的肿瘤。任何传感器都无法检测到更小的肿瘤部分。
