Electrical Impedance tomography – recent applications and developments

Abstract Electrical impedance tomography (EIT) is a low-cost noninvasive imaging method. The main purpose of this paper is to highlight the main aspects of the EIT method and to review the recent advances and developments. The advances in instrumentation and in the different image reconstruction methods and systems are demonstrated in this review. The main applications of the EIT are presented and a special attention made to the papers published during the last years (from 2015 until 2020). The advantages and limitations of EIT are also presented. In conclusion, EIT is a promising imaging approach with a strong potential that has a large margin of progression before reaching the maturity phase.

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Using Extreme Learning Machines and the Backprojection Algorithm as an Alternative to Reconstruct Electrical Impedance Tomography Images

Biomedical Computing for Breast Cancer Detection and Diagnosis - Advances in Bioinformatics and Biomedical Engineering ◽

10.4018/978-1-7998-3456-4.ch002 ◽

2021 ◽

pp. 16-27

Author(s):

Juliana Carneiro Gomes ◽

Maíra Araújo de Santana ◽

Clarisse Lins de Lima ◽

Ricardo Emmanuel de Souza ◽

Wellington Pinheiro dos Santos

Keyword(s):

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Imaging Techniques ◽

Low Cost ◽

Computational Cost ◽

Extreme Learning Machines ◽

Impedance Tomography ◽

Learning Machines ◽

Electrical Potentials ◽

Reconstruction Methods

Electrical Impedance Tomography (EIT) is an imaging technique based on the excitation of electrode pairs applied to the surface of the imaged region. The electrical potentials generated from alternating current excitation are measured and then applied to boundary-based reconstruction methods. When compared to other imaging techniques, EIT is considered a low-cost technique without ionizing radiation emission, safer for patients. However, the resolution is still low, depending on efficient reconstruction methods and low computational cost. EIT has the potential to be used as an alternative test for early detection of breast lesions in general. The most accurate reconstruction methods tend to be very costly as they use optimization methods as a support. Backprojection tends to be rapid but more inaccurate. In this work, the authors propose a hybrid method, based on extreme learning machines and backprojection for EIT reconstruction. The results were applied to numerical phantoms and were considered adequate, with potential to be improved using post processing techniques.

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Survey on Medical Imaging of Electrical Impedance Tomography (EIT) by Variable Current Pattern Methods

Journal of ISMAC - June 2019 ◽

10.36548/jismac.2021.2.002 ◽

2021 ◽

Vol 2 (2) ◽

pp. 82-95

Author(s):

Edriss Eisa Babikir Adam ◽

Sathesh

Keyword(s):

Image Reconstruction ◽

Medical Imaging ◽

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Optical Tomography ◽

Assessment Process ◽

Current Direction ◽

Impedance Tomography ◽

Research Article ◽

Reconstruction Methods

Recently, the image reconstruction study on EIT plays a vital role in the medical application field for validation and calibration purpose. This research article analyzes the different types of reconstruction algorithms of EIT in medical imaging applications. Besides, it reviews many methods involved in constructing the electrical impedance tomography. The spatial distribution and resolution with different sensitivity has been discussed here. The electrode arrangement of various methods involved in the EIT system is discussed here. This research article comprises of adjacent drive method, cross method, and alternative opposite current direction method based on the voltage driven pattern. The assessment process of biomedical EIT has been discussed and investigated through the impedance imaging of the existent substances. The locality of the electrodes can be calculated and fixed for appropriate methods. More specifically, this research article discusses about the EIT image reconstruction methods and the significance of the alternative opposite current direction approach in the biomedical system. The change in conductivity test is further investigated based on the injection of current flow in the system. It has been established by the use of Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EDITORS) software, which is open-source software.

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Development of a Portable, Reliable and Low-Cost Electrical Impedance Tomography System Using an Embedded System

Electronics ◽

10.3390/electronics10010015 ◽

2020 ◽

Vol 10 (1) ◽

pp. 15

Author(s):

Francisco Zamora-Arellano ◽

Oscar Roberto López-Bonilla ◽

Enrique Efrén García-Guerrero ◽

Jesús Everardo Olguín-Tiznado ◽

Everardo Inzunza-González ◽

...

Keyword(s):

Image Reconstruction ◽

Embedded System ◽

Electrical Impedance Tomography ◽

Food Industry ◽

Electrical Impedance ◽

Low Cost ◽

Computational Cost ◽

Raspberry Pi ◽

Impedance Tomography ◽

The Real

Electrical impedance tomography (EIT) is a useful procedure with applications in industry and medicine, particularly in the lungs and brain area. In this paper, the development of a portable, reliable and low-cost EIT system for image reconstruction by using an embedded system (ES) is introduced herein. The novelty of this article is the hardware development of a complete low-cost EIT system, as well as three simple and efficient algorithms that can be implemented on ES. The proposed EIT system applies the adjacent voltage method, starting with an impedance acquisition stage that sends data to a Raspberry Pi 4 (RPi4) as ES. To perform the image reconstruction, a user interface was developed by using GNU Octave for RPi4 and the EIDORS library. A statistical analysis is performed to determine the best average value from the samples measured by using an analog-to-digital converter (ADC) with a capacity of 30 kSPS and 24-bit resolution. The tests for the proposed EIT system were performed using materials such as metal, glass and an orange to simulate its application in food industry. Experimental results show that the statistical median is more accurate with respect to the real voltage measurement; however, it represents a higher computational cost. Therefore, the mean is calculated and improved by discarding data values in a transitory state, achieving better accuracy than the median to determine the real voltage value, enhancing the quality of the reconstructed images. A performance comparison between a personal computer (PC) and RPi4 is presented. The proposed EIT system offers an excellent cost-benefit ratio with respect to a traditional PC, taking into account precision, accuracy, energy consumption, price, light weight, size, portability and reliability. The proposed EIT system has potential application in mechanical ventilation, food industry and structural health monitoring.

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Feasibility of Temperature Control by Electrical Impedance Tomography in Hyperthermia

Cancers ◽

10.3390/cancers13133297 ◽

2021 ◽

Vol 13 (13) ◽

pp. 3297

Author(s):

Redi Poni ◽

Esra Neufeld ◽

Myles Capstick ◽

Stephan Bodis ◽

Theodoros Samaras ◽

...

Keyword(s):

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Reference Model ◽

Low Cost ◽

Temperature Reconstruction ◽

Voltage Measurement ◽

Noninvasive Technique ◽

Impedance Tomography ◽

Reconstruction Methods ◽

The Impact

We present a simulation study investigating the feasibility of electrical impedance tomography (EIT) as a low cost, noninvasive technique for hyperthermia (HT) treatment monitoring and adaptation. Temperature rise in tissues leads to perfusion and tissue conductivity changes that can be reconstructed in 3D by EIT to noninvasively map temperature and perfusion. In this study, we developed reconstruction methods and investigated the achievable accuracy of EIT by simulating HT treatmentlike scenarios, using detailed anatomical models with heterogeneous conductivity distributions. The impact of the size and location of the heated region, the voltage measurement signal-to-noise ratio, and the reference model personalization and accuracy were studied. Results showed that by introducing an iterative reconstruction approach, combined with adaptive prior regions and tissue-dependent penalties, planning-based reference models, measurement-based reweighting, and physics-based constraints, it is possible to map conductivity-changes throughout the heated domain, with an accuracy of around 5% and cm-scale spatial resolution. An initial exploration of the use of multifrequency EIT to separate temperature and perfusion effects yielded promising results, indicating that temperature reconstruction accuracy can be in the order of 1 ∘C. Our results suggest that EIT can provide valuable real-time HT monitoring capabilities. Experimental confirmation in real-world conditions is the next step.

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