Global and regional degree of obstruction determined by electrical impedance tomography in patients with obstructive ventilatory defect.

Background: Electrical impedance tomography is a continuous imaging method capable of measuring lung volume changes. The purpose of this study was to examine whether EIT was capable of evaluating the degree of obstructive ventilatory defect (OVD) on the global and regional level.

Methods: 41 healthy subjects with no lung diseases and 67 subjects suffering from obstructive lung diseases were examined using EIT and spirometry during forced vital capacity (FVC) maneuver.

Static imaging of the electrical impedance tomography on cylinder physical phantom.

Static imaging of the electrical impedance tomography can obtain the absolute electrical conductivity distribution at one section of the subject. The test is performed on a cylinder physical phantom in which slim rectangle, hollow cylinder, small rectangle or three cylinders are selected to simulate complex conductivity perturbation objects. The measurement data is obtained by a data acquisition system with 32 compound electrodes.

Correlation between the dielectric properties and biological activities of human ex vivo hepatic tissue.

Dielectric properties are vital biophysical features of biological tissues, and biological activity is an index to ascertain the active state of tissues. This study investigated the potential correlation between the dielectric properties and biological activities of human hepatic tissue with prolonged ex vivo time through correlation and regression analyses. The dielectric properties of 26 cases of normal human hepatic tissue at 10 Hz to 100 MHz were measured from 15 min after isolation to 24 h at 37 °C with 90% humidity.

Dielectric properties of human liver from 10 Hz to 100 MHz: normal liver, hepatocellular carcinoma, hepatic fibrosis and liver hemangioma.

The dielectric properties of human liver were determined by characterization of tissue absorption and coupling of electromagnetic energy in the electromagnetic field. In this study the ex-vivo dielectric properties of human hepatocellular carcinoma (well and moderately differentiated), liver hemangioma, hepatic fibrosis (stages S1 and S2), and normal liver tissue were measured and analyzed over the frequency range of 10 Hz to 100 MHz. The dielectric properties over the frequency range can reflect tissue information including biological macromolecules, vesicles, and cellular membrane; these information aids in distinguishing different physiological states and lesions.

Exploratory study on the methodology of fast imaging of unilateral stroke lesions by electrical impedance asymmetry in human heads.

Stroke has a high mortality and disability rate and should be rapidly diagnosed to improve prognosis. Diagnosing stroke is not a problem for hospitals with CT, MRI, and other imaging devices but is difficult for community hospitals without these devices. Based on the mechanism that the electrical impedance of the two hemispheres of a normal human head is basically symmetrical and a stroke can alter this symmetry, a fast electrical impedance imaging method called symmetrical electrical impedance tomography (SEIT) is proposed.

The correlation between dielectric properties and microstructure of femoral bone in rats with different bone qualities.

Bone dielectric properties (DP) have been extensively studied. However, little literature has reported DP of bone from identical anatomical site under different status and its correlation with microstructure. Therefore, interrelationship between DP and microstructure of rat femurs with varying bone qualities (normal, osteoporotic and partially osteoporotic) was investigated.

Design and optimization of multi-class series-parallel linear electromagnetic array artificial muscle.

Skeletal muscle exhibiting complex and excellent precision has evolved for millions of years. Skeletal muscle has better performance and simpler structure compared with existing driving modes. Artificial muscle may be designed by analyzing and imitating properties and structure of skeletal muscle based on bionics, which has been focused on by bionic researchers, and a structure mode of linear electromagnetic array artificial muscle has been designed in this paper.

A new head phantom with realistic shape and spatially varying skull resistivity distribution.

Brain electrical impedance tomography (EIT) is an emerging method for monitoring brain injuries. To effectively evaluate brain EIT systems and reconstruction algorithms, we have developed a novel head phantom that features realistic anatomy and spatially varying skull resistivity. The head phantom was created with three layers, representing scalp, skull, and brain tissues.

Improved circuit model of open-ended coaxial probe for measurement of the biological tissue dielectric properties between megahertz and gigahertz.

This note describes an improved equivalent circuit analysis model for open-ended coaxial probes for measurement of the dielectric properties of biological tissues below the gigahertz level. Some parameters in the conventional model that influence the measurement results were found to be still relative to the dielectric properties of the test sample and the terminal admittance of the probe was found to be dependent on the frequency. This was not found to be the case with the conventional model.

Reliability of in vivo measurements of the dielectric properties of anisotropic tissue: a simulative study.

A simulative study was performed to measure the dielectric properties of anisotropic tissue using several in vivo and in vitro probes. COMSOL Multiphysics was selected to carry out the simulation. Five traditional probes and a newly designed probe were used in this study.

A bio-impedance probe to assess liver steatosis during transplant surgery.

This work addresses the design of a bioimpedance probe to assess steatosis on the exposed liver in the donor during liver transplant surgery. Whereas typically bioimpedance uses needle probes to avoid surface effects, for clinical reasons a non-penetrative probe is required. In addition the need to ensure that the measurement is representative of the bulk tissue suggests a larger probe than is normally used to ensure a sufficiently large measurement volume.

[Gentiana veitchiorum particles inhibited LPS induced pulmonary alveolar macrophages (AM) TNF-α production and the underlying mechanism].

Aim: To investigate the effect of Gentiana veitchiorum particles on the expression of TNF-α in pulmonary alveolar macrophages (AM) which induced by LPS, to explain the mechanism about anti-inflammatory action of Gentiana veitchiorum particles.

Methods: Purification of rat AM, TNF-α level in AM culture supernatant was detected by ELISA. Western blot method for detecting the expression of TNF-α and pERK in the AM.

An optimized strategy for real-time hemorrhage monitoring with electrical impedance tomography.

Delayed detection of an internal hemorrhage may result in serious disabilities and possibly death for a patient. Currently, there are no portable medical imaging instruments that are suitable for long-term monitoring of patients at risk of internal hemorrhage. Electrical impedance tomography (EIT) has the potential to monitor patients continuously as a novel functional image modality and instantly detect the occurrence of an internal hemorrhage.

Comparison of three kinds of electrode-skin interfaces for electrical impedance scanning.

Low, uniform, and stable electrode-skin impedance is required to achieve good performance of the electrode-skin interface for electrical impedance scanning (EIS) examination. This can be used to measure the real impedance distribution of breast tissue beneath the skin. In this study, the gel interface, the cotton fine grid thin layer (CFGTL) interface, and the hydrogel interface were compared.

Modeling the frequency dependence of the electrical properties of the live human skull.

An accurate impedance model of a skull plays an important role in the simulation research on source localization of EEG and brain EIT (electrical impedance tomography), etc. On the basis of the large number of impedance and resistivity data obtained from our previous measurement on the live human skull, in this study we established the equivalent circuit models of six types of skull samples in the 30 Hz-3 MHz frequency range and analyzed the fitting performance of the models. The six types of skull samples are standard tri-layer, quasi-tri-layer, standard compact, quasi-compact, dentate suture and squamous suture.

Application of electrical impedance tomography for continuous monitoring of retroperitoneal bleeding after blunt trauma.

Retroperitoneal bleeding is commonly associated with blunt trauma to the abdomen. Current medical tools cannot be used for continuous monitoring of the bleeding. In the study, electrical impedance tomography (EIT) was applied to monitoring the retroperitoneal bleeding of an animal model.

Novel electrode-skin interface for breast electrical impedance scanning.

The high false-positive rate in clinical examinations limits the application of electrical impedance scanning (EIS) on breast cancer detection. One of the reasons is the non-uniform electrode-skin interface, which induces the 'contact artifact' in the results. To decrease the 'contact artifact', we designed a novel disposable electrode-skin interface [cotton fine grid thin layer (CFGTL)-interface], which is 0.

[A preliminary study of piglet intraperitoneal bleeding model and electrical impedance tomography monitoring].

Piglets having each a body weight of 20-30 kg and an abdominal perimeter like human's were used in the experiment. Being guided by ultrasound, we stabbed the piglet's abdomen, placed a catheter on the liver's lower margin, then injected the anticoagulated blood through the catheter by electrical infusion pump with constant speed respectively, and monitored the whole process by EIT. We observed the image change, using Ultrasound and CT to examine the area of blood injection after the end of monitoring,and we dissected to check the result of observations.

Preliminary imaging results of magnetic induction tomography based on physical phantom.

Magnetic induction tomography (MIT) is a kind of contactless and noninvasive method to reconstruct the conductivity distribution in a cross-section. We developed a data acquisition system with one exciting coil and 15 measuring coils. By rotating the object placing on a circle plate, the 16*15 measurement data were obtained.

Preliminary research on monitoring of cerebral ischemia using electrical impedance tomography technique.

More than half of the stroke patients are cause by cerebral ischemia/ hypoxia, and it is by no means an easy affairs to detect ischemic tissue when it is rescuable by drug intervention using traditional imaging technique. The purpose of this paper is to testify the feasibility of monitoring cerebral ischemia. By a newly developed high precision data acquisition system and specially configured imaging method, a series of imaging monitoring experiments were performed on 8 Chinese local rabbits, who have been induced with cortical ischemia by photochemical method.

Monitoring retroperitoneal bleeding model of piglets by electrical impedance tomography.

To investigate continuous monitoring capacity of electrical impedance tomography (EIT) for retroperitoneal bleeding, studies were carried out on six anesthetized piglet's bleeding model produced by injecting anticoagulated blood into renal region. For each subject, total blood of about 200 ml was injected within time periods ranging from tens of minutes to several hours. The simulated bleeding processes were detected and monitored by EIT system with sixteen electrodes at a rate of one image per second.

Improvement in EIS diagnosis accuracy using a multi-frequency parameter analysis method: preliminary results.

In this work we assessed the validity of the multi-frequency parameter (MFP) analysis method in distinguishing EIS false positive results. We chose 15 subjects with invasive duct carcinoma as the control group in which EIS results were all positive. In the experiment, three test groups-the Contact, the Skin and the Horm groups-were set to correspond to three common types of EIS false results.

Correlation between structure and resistivity variations of the live human skull.

A study on correlation between structure and resistivity variations was performed for live adult human skull. The resistivities of 388 skull samples, excised from 48 skull flaps of patients undergoing surgery, were measured at body temperature (36.5 degrees C) using the well-known four-electrode method in the frequency range of 1-4 MHz.

A quantitative method based on total relative change for dynamic electrical impedance tomography.

We proposed a new method based on total relative change (TRC) from measured boundary voltages to quantify the volume changes of fluid during electrical impedance tomography (EIT) monitoring. The results showed that TRC linearly correlated with the volume of infused saline solution into a phantom, and the slope of TRC changes was approximately linear with the infusion speed. A inserted copper tube at different positions did not affect TRC significantly.