Electrical impedance
The EIT uses a series of electrodes spread across the chest to generate cross-sectional images of the internal distribution of electrical impedance. The electrodes send and receive electrical impulses, and the image of the thorax shows the areas that change in volume most dramatically. Electrical impedance in thoracic images is high in areas that are well-ventilated, and low in regions that do not have a significant change in volume.
The system is composed of many components, including electrode array, data acquisition, and image reconstruction. In addition, a digital controller is used to process the images. The electrodes and the system are connected to a digital controller, and the image is reconstructed from the data.
Adaptive current tomography
Adaptive current tomography is an imaging technique that enables physicians to see the internal structures of the body. It uses an array of electrodes, either 32 or 64, that each have their own current generator. The electrodes measure the impedance of the body tissue and provide the data needed to reconstruct an image.
Adaptive current tomography has the potential to measure the internal temperature of deep-seated cancer without invasive procedures. This technique works on the principle that the electrical properties of biological tissues are nearly identical to those of saline solution. The resulting effective electrical impedance is found at the interface due to an electrochemical reaction.
Time difference electrical impedance
Electrical impedance tomography (EIT) is a noninvasive, radiation-free, and inexpensive imaging modality. Its time-difference form is particularly useful for capturing the dynamic changes in diseases. Bioimpedance varies with tissue composition, which includes the content of extracellular water, the presence of electrolytes, and the number of connections between cells. The presence of air, fat, and bone also increases bioimpedance. Changes in tissue composition during pathological processes result in a change in bioimpedance. Because the lungs are located so close to the surface of the body, EIT images can detect large changes in lung volume.
EIT is a noninvasive technique that allows the clinician to monitor respiratory processes at the bedside. The method requires an electrode belt containing at least 16 electrodes (in most recent models), a reference electrode connected to the central body, and a reference electrode connected to a central body point. In the measurement plane, the electrode belt lies in one transverse plane, with the diaphragm sometimes entering it.
Bioimpedance
Bioimpedance is a measure of the electrical properties of the body. Body fat has a high resistivity and blood has a low resistivity. Bioimpedance is measured by applying a small electric current and picking up a voltage. The lower the voltage, the lower the tissue impedance is for a given current. An example of a bioimpedance measurement device is a cylinder with electrodes placed around it. Skin surface band electrodes are also used.
Bioimpedance measurements are used in many health applications, including clinical medicine and biomedical engineering. In particular, bioelectric parameters have been associated with physiological and anatomical properties to help distinguish between different types of medical conditions. While there is currently no established noninvasive method for bone fracture diagnostics, recent ex vivo and in vivo bioimpedance procedures have shown promising results. In fact, 59 articles have reviewed or mentioned the ability of bioimpedance to assess long bone integrity.
