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.

A multifrequency time-difference electrical impedance tomography algorithm using spectral constraints / 生物医学工程学杂志

This study aims to propose a multifrequency time-difference algorithm using spectral constraints. Based on the knowledge of tissue spectrum in the imaging domain, the fraction model was used in conjunction with the finite element method (FEM) to approximate a conductivity distribution. Then a frequency independent parameter (volume or area fraction change) was reconstructed which made it possible to simultaneously employ multifrequency time-difference boundary voltage data and then reduce the degrees of freedom of the reconstruction problem. Furthermore, this will alleviate the illness of the EIT inverse problem and lead to a better reconstruction result. The numerical validation results suggested that the proposed time-difference fraction reconstruction algorithm behaved better than traditional damped least squares algorithm (DLS) especially in the noise suppression capability. Moreover, under the condition of low signal-to-noise ratio, the proposed algorithm had a more obvious advantage in reconstructions of targets shape and position. This algorithm provides an efficient way to simultaneously utilize multifrequency measurement data for time-difference EIT, and leads to a more accurate reconstruction result. It may show us a new direction for the development of time-difference EIT algorithms in the case that the tissue spectrums are known.

Efficacy comparison of three different treatment of internal fixation of intervetebral crasis on spinal cord cervical spondylosis / 重庆医学

Objective To observe the difference of efficacy of three different treatment of internal fixation of intervetebral crasis on cervical spondylosis (spinal cord) .Methods From January 2009 to January 2013 ,There are 167 cases of patients admitted to hospital from cervical spondylosis (spinal cord ) ,randomly selected different fusion fixation methods are divided into three groups :in the first group ,there were 55 patients treated with autologous iliac bone graft fusion plate fixation ;in the second group , there were 60 patients treated with zero profile material PEEK interbody fusion with autologous bone graft ;in the third group ,the 52 patients were treated with the PEEK material MC + self‐locking cervical interbody fusion with autologous bone graft .Observa‐tion and comparison indicators include :spinal cord function JOA scores before and after surgery ,surgical segment intervertebral height and cervical curvature condition .Results Follow‐up lasted from 13 to 50 months ,the average length was 26 months .The difference in operation time ,blood loss during surgery analysis ,wherein the first group and the second or third group of three groups was statistically significant (P0 .05) .In the first group ,there were 17 patients had transient throat discomfort and symptom disappeared 48 hours later ;dysphagia relieved or disappeared in one week ;there were two cases of screws and titanium loosen one week after operation , and were treated with immediate revision surgery .In the second ,third group ,there were 19 cases and 13 cases showed temporary throat discomfort disappeared within 48 hours after surgery respectively ,there was no dysphagia .No patient experienced cerebrospi‐nal fluid leakage ,hematoma and wound infection .The postoperative JOA scores spinal cord function (17 points France) ,surgical segmental cervical intervertebral height and curvature of three groups improved significantly compared with preoperative evaluation index ,and there was no significant difference among three groups (P>0 .05) .In the last follow‐up ,the interbody fusion rates of the first ,second and third groups were 67 .1% ,66 .3% and 65 .9% ,the difference between groups was not statistically significant (P>0 .05) .Conclusion Anterior decompression and interbody fusion locking device applications showed good performance in maintai‐ning the intervertebral height segment surgery ,rehabilitation cervical curvature ,and promote bone fusion with autogenous titanium plate fixation comparison .Patients can get a good surgery ,and the former has a simpler surgical fixation method ,shorter time ,less bleeding and less complications .

Breast cancer detection based on multi-frequency EIS measurement.

As a convenient, un-injurious and low cost method for women breast tumor diagnosis, Electrical Impedance Scanning (EIS) is being paid increasing attention. But EIS still has some problems. In theory the malignant tumor has higher electrical conductivity than normal tissue and benign tumor, so the cancer will be recognized in the EIS image as a bright spot. However, in practical the difference is not so obvious. In many cases it is difficult to judge whether a suspicious bright spot tells a malignant or benign tumor. This paper concerns a new method based on multi-frequency EIS measurement to solve this problem. A group of scanning results with various stimulating frequencies will be performed during an EIS measurement, which is automatically controlled by specially designed device and the location and pressure of the sensor will keep stable, so we will get a series of data at different stimulating frequencies through a measurement. Because the malignant and the benign tumor have different curves in electrical conductivity-frequency diagram, we can analyze the data at every frequency and find out the attribute of the tumor. Clinical trails have been carried out. Subjects were suspicious sufferers that were to receive histopathology examinations, and all analyses have been compared with histopathology results.

Short pulse eye-safe laser with a stimulated Raman scattering self-conversion based on a Nd:KGW crystal.

We present the results of a solid self-Raman laser based on a Nd:KGW crystal that is transversely pumped by laser diode bars. A beam of an eye-safe laser with a 31.8 mJ output energy and a 2.0 ns pulse width was obtained by applying a special s-polarized reflective resonator configuration in which the length of the Raman resonator was shorter than that of the fundamental radiation resonator. The eye-safe laser has the highest output energy and the shortest pulse width among the Nd:KGW lasers ever reported.

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.

Method for obtaining prior information of electrical impedance tomography / 医疗卫生装备

The reverse problem of Electrical impedance tomography(EIT) is a highly ill-posed problem.It is concluded that spatial prior information could improve the final image quality.This paper proposes a new method for obtaining prior information.By this method,the inspected cross-section contour and internal structure for EIT can be achieved.

Comparison of Performances of Ag/AgCl Coating Electrodes and Pulverized Electrodes in Cerebral Application of Electrical Impedance Tomography / 医疗卫生装备

Objective To compare the performance of novel Ag/AgCl pulverized electrodes with conventional Ag/AgCl coating electrodes in cerebral application of Electrical Impedance Tomography(EIT).Methods Based on the EIT system developed by our group,raw data were measured on a phantom and an adult volunteer,with Ag/AgCl coating electrodes and pulverized electrodes,respectively.The performances of electrode systems were evaluated in contact impedance and two other figures(the high-frequency SNR,HFSNR;the low-frequency SNR,LFSNR).Results Ag/AgCl pulverized electrode plays a better performance in resisting noise and keeping stabilization.Conclusion Ag/AgCl pulverized electrode develops the needs of imaging and monitoring human brains in EIT more availably.

Comparison of Performances of Three Kinds of Direct Current Power Source in the Application of Electrical Impedance Tomography(EIT) / 医疗卫生装备

Objective To provide the hardware system of EIT with an excellent direct current(DC) power source. Methods The spectrums of the outputs of DC power source and the driving source were analyzed by means of Spectrum Analyzer- E4408B when EIT system was respectively powered by battery, linear power source and switching power source. Based on the numbers and power levels of the spurs of the three power sources and the numbers and power levels of the interferences within the driving source, the influence of the three power sources on the error of measuring was estimated. Meanwhile the EIT system did data acquisition, the overall signal-to-noise-ratio(SNR) of the three power sources at the 18 frequencies were calculated and the influence of the three power sources on the error of measuring was judged. Results With respect to the numbers and power levels of the interferences within the driving source when EIT was powered respectively by the three power sources, the battery output 6 interferences, the highest power of which achieved -78.25 dBm; the linear power source output 6 interferences, the highest power of which achieved -67.11 dBm; the switching power source output 15 interferences, the highest power of which achieved -35.83 dBm. The overall SNRs of the battery at the 18 driving frequencies were higher than that of the linear power source, and the overall SNRs of the linear power source were higher than that of the switching power source. Conclusion The power mode of battery is the best for the hardware of EIT among the three power sources.