Bipolar current injection methods for electrical impedance tomography: a comparative study
13 Mar 2017-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 10137, pp 1013718
TL;DR: Based on the simulation studies and experimental validations, cross method is found to be the optimal current injection method to attain better data acquisition and image reconstruction.
Abstract: A comparative study of different bipolar current injection methods viz. Adjacent method, Cross method and Opposite method used in Electrical Impedance Tomography(EIT) is reported in this paper. Different electrode configurations are considered for current injection and voltage measurement to identify the one which yields better signal strength. Sensitivity of different current injection methods to inhomogeneity at different locations is examined. The effect of conductivity contrast on boundary voltages is studied by varying the conductivity of the inhomogeneity from 0.01mS/cm to 9.1mS/cm. Ill-posedness of the inverse problem is analyzed in terms of condition number for the aforementioned methods. Reconstruction of two closely placed inhomogeneities is done using Levenberg Marquardt method for different current injection methods to compare the resolution and corresponding error voltage is determined. Experiments are conducted using agar phantoms to validate some of the results obtained from the simulations. Based on the simulation studies and experimental validations, cross method is found to be the optimal current injection method to attain better data acquisition and image reconstruction.
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TL;DR: Electrical impedance tomography (EIT) was able to sensitively detect hemothorax as small as 10 ml in volume, as well as its location, and demonstrated that EIT has a unique potential for early diagnosis and continuous monitoring of hemothsorax in clinical practice.
Abstract: Hemothorax is a serious medical condition that can be life-threatening if left untreated. Early diagnosis and timely treatment are of great importance to produce favorable outcome. Although currently available diagnostic techniques, e.g., chest radiography, ultrasonography, and CT, can accurately detect hemothorax, delayed hemothorax cannot be identified early because these examinations are often performed on patients until noticeable symptoms manifest. Therefore, for early detection of delayed hemothorax, real-time monitoring by means of a portable and noninvasive imaging technique is needed. In this study, we employed electrical impedance tomography (EIT) to detect the onset of hemothorax in real time on eight piglet hemothorax models. The models were established by injection of 60 ml fresh autologous blood into the pleural cavity, and the subsequent development of hemothorax was monitored continuously. The results showed that EIT was able to sensitively detect hemothorax as small as 10 ml in volume, as well as its location. Also, the development of hemothorax over a range of 10 ml up to 60 ml was well monitored in real time, with a favorable linear relationship between the impedance change in EIT images and the volume of blood injected. These findings demonstrated that EIT has a unique potential for early diagnosis and continuous monitoring of hemothorax in clinical practice, providing medical staff valuable information for prompt identification and treatment of delayed hemothorax.
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Cites methods from "Bipolar current injection methods f..."
...To increase the sensitivity to changes in impedance caused by central lung regions and maintain a good signal-to-noise ratio, the protocol of opposite excitation-adjacent measurement protocol was adopted in EIT data acquisition [38]....
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TL;DR: In this article, a five percent by-mass agar model augmented with small amounts of suspended wheat flour was presented as a model that could generate an ultrasound image that remarkably resembled that of real tissue.
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