Online Tissue Discrimination for Transcutaneous Needle Guidance Applications Using Broadband Impedance Spectroscopy

Abstract

This paper reports on a novel system architecture for measuring impedance spectra of a biological tissue close to the tip of a hollow needle. The measurement is performed online using fast broadband chirp signals. The time domain measurement raw data are transformed into the transfer function of the tissue in frequency domain. Correlation technique is used to analyze the characteristic shape of the derived tissue transfer function with respect to known "library functions" for different types of tissue derived in earlier experiments. Based on the resulting correlation coefficients the exact type of tissue is determined. A bipolar coaxial needle is constructed, simulated by finite element method and tested during various in vitro and in vivo experiments. The results show a good spatial resolution of approximately 1.0 mm for a needle with a diameter of 2.0 mm. The correlation coefficients for the three tested tissue types muscle, fat, and blood allow for a clear tissue classification. Best results have been obtained using the characteristic phase diagrams for each tissue. Correlated to the corresponding library transfer function the coefficients are in the range of +0.96 to +0.99 for the matching tissue. In return, the resulting coefficients for correlation with nonmatching tissues are in the range of -0.93 to +0.81.

Sensor, Signal, and Imaging Informatics: Evidence-Based Health Informatics

“…Some evaluations consist of pre-clinical experiments on a small amount of tissue (e.g. [2,4,5]) or clinical data (e.g. [7,8]) and experiments on small animals (e.g.…”

“…The malignancy of a tissue can be determined without contact thanks to hyperspectral imaging [3] or spectroscopic imaging [4]. On the other hand, [5] presents a contact-based approach for discriminating between three tissue types (muscle, fat and blood) with the development of a broadband impedance spectroscopy needle.…”

Fractional transmission line model of oil‐immersed transformer windings considering the frequency‐dependent parameters

“…During the measurement, a certain sample is nipped between the two additional electrodes of the sample holder [11]. Meanwhile, the nitrogen is continuously bubbled into the constant temperature system for eliminating the influence of moisture in the environment.…”

Lock-in Amplifier-Based Impedance Detection of Tissue Type Using a Monopolar Injection Needle

“…The frequency-dependent electrical properties, conductivity and permittivity, of the biological tissues differ significantly from each other [23]. Previous literature reported the feasibility of the needle with different electrode configurations (monopolar, bipolar, or quadripolar) for the impedance characterization of the tissue types [15,16,19,24,25]. For operating the intra-articular injection therapy, the path of the needle insertion is determined to pass through the dermis, hypodermis, or muscle layer.…”