You Fusheng

High precision Multifrequency Electrical Impedance Tomography System and Preliminary imaging results on saline tank

To establish a high precision data acquisition system for multi-frequency electrical impedance tomography (EIT), a series of methods were introduced. Those methods include building a driving signal with up to four frequency components to diminish the effect of the dynamic change of tissues resistivity, extracting the impedance information by a digital demodulator that can improve the SNR by 8 times. The system that established can work at a wide range from 1.6 kHz to 380 kHz. Its CMRR is 74 dB at 100 kHz. The output impedance of current source is 2 MOmega at that frequency. And measurement precision on a 100 ohm resistor is better than -80 dB in full bandwidth. Both the quasi-static and the dynamic imaging results based on a saline tank can reflect the resistivity changes inside the phantom clearly. Therefore, the system was competent in multifrequency EIT research work

Image monitoring for an intraperitoneal bleeding model of pigs using electrical impedance tomography.

Current medical imaging techniques are not effective for timely detection of internal hemorrhage when the bleeding is slow and in small quantities. In this study, electrical impedance tomography (EIT) was applied to monitor the intraperitoneal bleeding of an animal model. Five healthy pigs three months old were used. The process of intraperitoneal bleeding was simulated with the injection of anticoagulated blood which was controlled by an electronic syringe pump. The injected rate was no more than 100 ml h(-1) and the total injection volumes ranged from 300 ml to 500 ml. Sixteen electrodes were attached to the abdomen and used for electrical current excitation and surface voltage measurement. Dynamic changes in impedance distribution within the abdomen were calculated by the back-projection algorithm and a series of EIT images were displayed in a unified range. The monitoring was performed with EIT at a rate of one frame per second and continued for at least 4 h. Intraperitoneal blood volume changes could be identified by inspection of consecutive EIT images during the progression of blood injection. 30 ml of blood in the peritoneum could be detected. EIT was shown to be a promising technique for continuous monitoring of intraperitoneal bleeding over periods of time.

Electrical impedance tomography reconstruction algorithm based on general inversion theory and finite element method.

A strict EIT reconstruction algorithm, the general inversion algorithm (GIA) is presented. To improve the noise performance, the algorithm is modified by attenuating the condition number of the forward matrixF and implemented using an improved FEM scheme, to obtain the 2D image of impedance change (dynamic image). This modified general inversion algorithm (MGIA) can be used on a larger dimension FEM model (248 elements) and is more practical than the GIA. When implementing this algorithm in computer simulation and in a physical phantom, it is found that the MGIA has a smaller reconstruction error than the currently used algorithms (equipotential-back-projection algorithm and filtered spectral expansion algorithm). With 0.1% white noise in the data, the algorithm can still reconstruct images of a complicated model. Further improvements are also discussed.

An image monitoring system for intraperitoneal bleeding using electrical impedance tomography and its preliminary results in vivo

An image monitoring system using electrical impedance tomography (EIT) for intraperitoneal bleeding was designed (FMMU V3.5). It consists of a constant current driving source with frequency of 50 KHz, a high accuracy measurement module, a driving and measuring mode program-controlled circuits, a data acquisition card, an optoelectronic isolated digital I/O board, and a custom-specified linear power supply units. The system applied equal-potential back projection algorithm to reconstruct dynamic images. The relative accuracy of the system is 0.1%, the RTI noise is 11.1 mu V (bandwidth 100 Hz). Based on physical phantom, images reconstructed by the system showed that it can image dynamically to the infused saline solution, and by infusing more solution the gray changed area of the image also enlarged accordingly. For stomach filling model in vivo, the dynamic imaging processes showed that the system can clearly and sensitively monitoring the saline solution drinking into the stomach for 50 ml each time, and by drinking more saline solution the conductivity changed area of the dynamic image also enlarged accordingly

Study of Electrical Impedance Scanning System for Breast Screening

An electrical impedance scanning (EIS) system was studied to meet the requirement of clinical breast screening. A quick examination, easy operation, safe electrical isolation and obvious diagnosis results are four main factors to a screening system. Basing on these considerations, a multi-frequency signal sampling system controlled by ARM chip was setup and the measuring data were transmitted to PC by an ethernet interface. For the measuring probe, three types of electrodes array were designed to adapt the different sizes of breast. Additionally, an imaging post-process algorithm was developed to assist the radiologist to have an obvious diagnosis results. Based on a saline-tank phantom and some satisfying results were got. The system has a character of high precision, real-time imaging and obvious results and can be used in the clinical study of EIS breast screening.

Different Approaches to the Completion of the Back-Projection Algorithm in Image Monitoring by Electrical Impedance Tomography

It is found that electrical impedance tomography(EIT) is promising in its application to the clinical image monitoring and that the back-projection algorithm of EIT can meet the preliminary requirements of the real-time monitoring through our work. In order to improve the computed speed and the imaged resolution, different ways of completing the algorithm were tried in this paper. Moreover, it is shown that the impedance change due to physiological saline with the concentration of not more than 50 milliliter 0.9% can be detected and imaged by our system. The above result is helpful for our further work of image monitoring by EIT

The Influence of Position to Phase and Magnitude Detecting in Medical Magnetic Induction Imaging

A 16-channel magnetic induction imaging system is introduced briefly. Highly precise phase and magnitude detecting method is applied to the information acquisition. The resolution of phase detecting is 0.003deg. The results of magnitude detecting also provide us with useful information. The characteristic curves are smoother than that of our previous system. One dimension results in different positions of the measurement region demonstrate the trend of variation of the detected signals. The positions of the object affect the results greatly and the trend of variation is regular

Study on Disease Screening and Monitoring System Based on Wireless Communication and IOT

This paper presents a disease screening and monitoring telemedicine system based on wireless communication and the Internet of Things(IOT) aiming at building a people-oriented and ubiquitous telemedicine environment . This paper focuses on the system architecture and key technologies, as well as the implementation method, in order to provide a theoretical and technical basis for further demonstration projects.

Study of influencing factors on Electrical Impedance Scanning Imaging

Electrical impedance scanning (EIS) is a new adjunctive diagnostic method for women breast cancer examination. In clinic research, we found some influencing factors which can induce a bad EIS imaging results. In order to analyze the influencing factors on EIS imaging and find the solutions, we set up an EIS workbench which can simulate the influencing factors that may happen in a clinic. We studied the influencing factors from size, depth of the target; the influence from the poor contact; the influence from the unparallel current field. The experiment results show that the detectability of EIS system is a function of the depth, the size and the area of electrodes; a good contact between the probe and the skin can decrease the artificial imaging; using the imaging algorithm can calibrate the imaging induced by unparallel current field

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. In the Contact group, false positive results were induced by poor contact of the measuring probe. In the Skin group, false positive results were induced by skin ridges. In the Horm group, false positive results were induced by a high hormone level. Based on the MFP analysis method, we obtained the Cole-Cole parameters of each subject in the control group and the test groups. Statistical analyses showed there was a significant difference in G(0N), G(infinity)N) or alpha(N) between the control group and the Contact or the Skin group. A significant difference between the control group and the Horm group existed only in alpha(N). These results suggested that by means of the MFP analysis method it was possible to distinguish between a false positive result and a positive result caused by breast cancer. In conclusion, the MFP analysis method appears to be a feasible means to improve the diagnosis accuracy of EIS for breast cancer detection.