Login to Access Video or Poster Abstract: MP73-14
Sources of Funding: None.

Introduction

To estimate tumor margin during partial nephrectomy, we developed a needle having electrochemical impedance spectroscopy (EIS) sensor on the tip of a needle which we named &[Prime]EoN (EIS-on-a needle)&[Prime]. In this study, the impedances of renal parenchyma in accordance with the distance from the tumor were measured by using EoN to evaluate the capability of the device in detecting the tumor margin.

Methods

Microelectromechanical-system technology was applied to fabricate EoN, which is a 22-gauge needle with interdigitated electrodes on its tip. For the experiment, 10 renal specimen consisted of tumor and its surgical margin resected by partial nephrectomy were used. EoN was inserted into the surgical margin of the specimens and the impedance was measured while the device was accessing toward the tumor at the frequency range from 0.1 kHz to 1 MHz. The areas within the specimens where the impedance was measured were categorized into five sections according to the distance from the tumor: 1) surgical margin at > 6 mm and ≤ 8 mm from the tumor as section I; 2) between > 4 mm and ≤ 6 mm as section II; 3) between > 2 mm and ≤ 4 mm as section III; 4) between > 0 mm and ≤ 2 mm as section IV; and 5) within the tumor as section V. The magnitude and phase angle of impedance between each sections were compared by using repeated-measures analysis of variance at each single frequency.

Results

The mean magnitude and phase angle of the impedances were proved to have a statistically significant variation (p <0.05) in accordance with the distance from the tumor at the frequency from 10.08 kHz to 1MHz and at 39.89 kHz, respectively. At these frequencies, the mean magnitude and phase angle of section V was significantly different (p <0.05) to that of at least one other section of the specimen. However, the mean impedance differences between each respective sections other than section V did not show any statistical significance.

Conclusions

The present thesis has proved the capability of EoN in detecting the tumor when EoN was inserted from the normal renal parenchyma. The depth of tumor margin beneath the renal surface is assumed to be measurable by estimating the inserted length of EoN which has reached an area showing significant change of impedance values at specific frequencies.

Funding

None.