Development of a noninvasive electrical impedance probe for minimally invasive tumor localization.

Compared with traditional open surgery, minimally invasive surgery (MIS) improves the accuracy and dexterity of a surgeon and minimizes trauma to the patient. However, the lack of significant haptic feedback in MIS can make tumor localization difficult. A noninvasive electrical impedance probe (NEIP), consisting mainly of two spherical electrodes and a constant force generator, has been developed to gently touch or slide over tissue surface and at the same time record impedance values without prior registration of the surface. We prove that there is a linear relationship between the surgical margin width and the recorded conductance. Ex vivo experiments in ten human kidney specimens were performed to demonstrate the feasibility of NEIP. The experimental results verify the linear relationship and indicate that NEIP can provide accurate tumor location while sliding over the tissue surface.