An electrical impedance tomography (EIT) multi-electrode needle-probe device for local assessment of heterogeneous tissue impeditivity

Abstract

Electrical Impedance Tomography (EIT) is an image reconstruction technique applied in medicine for the electrical imaging of living tissues. In literature there is the evidence that a large resistivity variation related to the differences of the human tissues exists. As a result of this interest for the electrical characterization of the biological samples, recently the attention is also focused on the identification and characterization of the human tissue, by studying the homogeneity of its structure. An 8 electrodes needle-probe device has been developed with the intent of identifying the structural inhomogeneities under the surface layers. Ex-vivo impeditivity measurements, by placing the needle-probe in 5 different patterns of fat and lean porcine tissue, were performed, and impeditivity maps were obtained by EIDORS open source software for image reconstruction in electrical impedance. The values composing the maps have been analyzed, pointing out a good tissue discrimination, and the conformity with the real images. We conclude that this device is able to perform impeditivity maps matching to reality for position and orientation. In all the five patterns presented is possible to identify and replicate correctly the heterogeneous tissue under test. This new procedure can be helpful to the medical staff to completely characterize the biological sample, in different unclear situations.

Development of switching and measurement circuits for problems of electric impedance tomography

“…There are many publications on the development of electric impedance tomography devices [3][4][5][6][7][8][9][10]. Paper [3] addresses the development of a low-cost implementation of the non-disruptive control system based on the EIT.…”

“…The device is based on the Arduino UNO board and the EIT board, which combines a probe signal generator and switches. Paper [4] tackles the development of an electrode system for the EIT and contains a description of the portable EIT system. Paper [5] includes a description of a data collection and transmission device based on the Arduino 2560 board with external switches and measurement of potentials relative to the common point.…”

Electrical Characterization of Pork Tissue Measured by a Monopolar Injection Needle and Discrete Fourier Transform based Impedance Measurement

“…Several research groups [6,17] reported the finite element simulation of the electric fields surrounding the needle tip in different tissue models. The electrical impedance tomography using a multi-electrode array is expected to provide the lateral and spatial information of the needle [27,28]. Finally, the feasibility of the intra-articular injection therapy based on the impedance monitoring with the monopolar injection needle and the algorithm to detect the target tissue will be tested in an animal model and clinical trials.…”

Electrical Impedance Tomography for Robot-Aided Internal Radiation Therapy

“…Although this approach is often sufficient in obtaining general information regarding the tissue it may not be able to discriminate between tissue conductivity deep underneath the surface. Tissue variations can exist well below the skin surface and electrodes may not able to detect this change in conductivity (Meroni et al, 2017 ). This is especially the case for prostate cancer (Meir and Rubinsky, 2015 ).…”

“…The physical distance and the neighboring organs can all attribute to noise in surface electrode measurements. In contrast, research has been conducted into utilizing internal electrodes that are placed within the object of interest, much like needles, in order to perform the imaging procedure (Halter et al, 2011 ; Mishra et al, 2011 , 2013 ; Wan et al, 2013 ; Fukushima et al, 2015 ; Meir and Rubinsky, 2015 ; Meroni et al, 2017 ; Kwon et al, 2018 ; Park et al, 2018 ; Abbasi et al, 2020 ). With the use of needle probes, the voltage measurements can be taken deep underneath the skin surface to the exact depth of the suspicious tissue under inspection.…”