Electrical Impedance Tomography: A Real-Time Medical Imaging Technique

Electrical Impedance Tomography: A Real-Time Medical Imaging Technique

Ramesh Kumar Meena (NIT Jalandhar, India), Sarwan Kumar Pahuja (NIT Jalandhar, India), Abdullah Bin Queyam (NIT Jalandhar, India) and Amit Sengupta (IIT Delhi, India)
DOI: 10.4018/978-1-5225-2848-7.ch006
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Presently, non-invasive techniques are in vogue and preferred standard clinical approach because of its limitless advantages in monitoring real time phenomenon occurring within our human body without much interference. Many techniques such as ultrasound, magnetocardiography, CT scan, MRI etc., are used for real time monitoring but are generally not recommended for continuous monitoring. The limitations created by above used techniques are overcome by a proposed technique called non-invasive bio-impedance technique such as Electrical Impedance Technique (EIT). EIT imaging technique is based on internal electrical conductivity distribution of the body. The reconstruction of cross sectional image of resistivity required sufficient data collection by finite element method using MATLAB software. The EIT technique offers some benefits over other imaging modalities. It is economical, non-invasive, user friendly and emits no radiation thus appears to be one of the best fit technology for mass health care to be used by the basic health worker at a community level.
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1. Introduction

Non-invasive techniques are the standard clinical approach because of its use in long term monitoring of the patients as well as industrial subject (Kumar et al., 2013). Alternatively, many techniques are used in medical area for patient monitoring like ultrasound, magnetocardiography (MCG), computerised tomography (CT) scan, magnetic resonance imaging (MRI) etc., but are generally not recommended for hours long monitoring and real time monitoring. Due to these limitations in real time monitoring, patient as well as medical personnel face inconvenience (Kumar et al., 2013). The restrictions created by above used techniques is overcome by a proposed method called non-invasive bio-impedance technique, such as, electrical impedance tomography and impedance plethesmosraphy (Holder, 2005). Many research groups have established EIT prototypes system and done lots of experimental study and clinical studies (Holder, 2005). Validation of EIT data was an important part in most of these studies. Regional distribution of ventilation has been associated to other medical techniques (Holder, 2005). Various studies also established that EIT technique associates the potential to occur as a useful of real time monitoring tool for clinical filed.

Formerly bio impedance measurement became a general method to determine the features of body tissue. With knowledge of the bio impedance of various points about an object testing, the interior conductivity distribution can be projected. This method is known as electrical impedance tomography (Holder, 2005). EIT was developed over 70 years ago for non-medical purposes by the Sheffield group. It is an imaging modality and also known as bio impedance imaging or tomography. In this the study of passive electrical properties of the biological tissues is done (Patterson, 2005). EIT is based on two main concepts. First, the fact that there is a large resistivity difference between a different types of tissue in human body which permits for the use of this resistivity difference to form anatomical images of that cross-section of human body. Second, there is clear dissimilarity between normal and pathological tissues which can be easily identified by measuring the resistivity difference or electrical distribution (Holder, 2005; Patterson, 2005).

Many studies also established that EIT technique associates the potential to emerge as a useful of real time monitoring tool for clinical filed. Presently, many EIT prototype are available for data acquisition of the object, such as, through the DSP kit switching, controller with multiplexer, multiplexer switching, electronic switching etc. similarly, many image reconstruction algorithms have been developed to check the field distribution in closed object. Such as that, using FEM, Neural Network, GUI based, EIDORs toolkit, several mathematical algorithms are available at present (Patterson, 2005). Many phantom studies are done which shows that EIT can be implemented in medical or industrial application. Subsequently, many other studies show trial of EIT technique on human volunteers at different-2 body locations such as brain, joints of body, abdomen etc. The EIT technique presented desired outcomes on a set of experiments done on many phantoms and has been compared. Results clearly presented that the electrical impedance tomography efficiently can be used to detect related to bio-physiological and morphological parameters of the human body and can be beneficial for medical mass healthcare applications. And the advantage of this technique is radiation free, non-invasive, inexpensive and portable monitoring to patients.

Key Terms in this Chapter

Inverse Problem: It is the process for manipulative the impedance distribution based on boundary voltages/potential of the object.

Bio Impedance: It is a normally used technique for approximating body composition, and in specific fat of the body and determines the electrical impedance, opposition of the flow of an electric current over the body tissues, then, compute and estimation of body mass and, other important parameter of the body.

Tomography: Is a technique for displaying an image (in form of slice) of a cross section through a medical or industrial object.

Forward Problem: It is the procedure for calculating the boundary potential based on impedance distribution of the object/subject.

Eidors: It is to encourage collaboration between groups working on Diffusion based Optical Tomography and Electrical Impedance Tomography, in non-medical and medical backgrounds. EIDORS is an imaging package for image reconstruction in electrical impedance tomography and diffuse optical tomography.

Phantom: A depiction, part of which is given a diaphanous effect so as to allow representation of details else hidden from view, as the inside workings of a mechanical device.

Plethysmogrpahy: It is a technique for measuring variations of the body and the size of an organ, on the basis of the amount of blood passing through or present in the part.

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