The development of EIT is summarized based on the concept and advantages of the Electrical impedance tomography (EIT) from the following three aspects: multi-frequency electrical impedance tomography (MEEIT), induced current electrical impedance tomography (ICEIT)and magnetic induction tomography (MIT). The advantages of the developing methods are expatiated and compared with the traditional EIT . The future application trend of them is pointed out. EIT is one of the key projects of biomedical engineering today. It is an ideal medical imaging technology with enticing prospect.

Electrical impedance tomography(EIT) is a novel medical imaging technique, which was developed in recent 20 years following morphology imaging and structure imaging. With the outstanding advantages of noninvasiveness, functional imaging, and medical image monitoring, EIT has a bright and fascinating future in medical application. This paper reviews the htest development of its clinical appLication both in our country and abroad, including measurement of lung density and air volume, strategy to enhance protective ventilation, breast cancer detection, virtual bladder biopsy, acute stroke imaging,and monitoring of intraperitoneal bleeding, etc.

During the digest course the electrical property of the stomach alters obviously due to the change in shape, dimension, volume of gastric and the composition of stomach. The regulation of the impedance change is corresponding to the gastric motility and the correlation between them is evident. The impedance technique can be used to monitor gastric motility function no-invasively with high sensitivity and accuracy. Based on introduction of the gastric motility function and its measurement method, the development, key technique and existing problem of the gastric motility measurement using the electrical bio-impedance method are reviewed in this paper.

In order to test validity and fea si bility of the impedance spectroscopy analysis method,a series of blood experime n ts have been carried out to study influences of the hematocrit,the plasma conc e ntration and the dextran concentration in suspend medium on the blood impedance and the RBC aggregation.The results show that the blood impedance of lower freq uency R_0 increases with increase of Hctc,the time constant T has little chang e when Hctc hange from 28.9 to 48.9;with the increase of plasma concentration ,t he RBC aggregation radius increases;When the dextran concentration is about 4g/ 100ml,the RBC aggregate reaches its maximum.It suggests that the impedance spe ctroscopy analysis method is a new,effective method to study RBC aggregation.

Objective From the Maxwell-Wagner theory for suspensions of spherical and the electrical property of blood,an equation has been derived to calculate RBC aggregate radius,a new method based on the impedance spectroscopy analysis has been developed to evaluate the Red Blood Cell (RBC) aggregation property. According the new method,the impedance spectroscopy of blood has been measured at first with the multi-frequency technique,then to get the impedance - frequency curve by a fit method,the time constant T has been extracted from the curve,at last,the RBC aggregate radius R has been gotten. According to the changes of R during the RBC aggregation,the measurement and evaluation of RBC aggregation property can be realized. The impedance spectroscopy analysis method introduced in this paper is a new,effective method to study RBC aggregation.

Objective To design and develop a quadrature demodulation circuit for detection of ampli-tude and phase information in EIT measurement. Methods A model structure file was built in matlab/simulink using the elements in Ahera DSP Builder and verified by simulated stimulation. Then the model file was convert-ed to VHDL file via Signal Compiler, and the synthesis, adaptation, simulation and hardware implementation were accomplished. Results The simulation and testing results show that the circuit can extract the real and imagi-nary information of the measured signal and it also meets the EIT measuring requirement, with acceptable mea-sure error. Conclusion The demodulation circuit based on DSP Builder can precisely give real and imaginary information of EIT and provides technological support for full-information complex impedance measurement.

Functional dyspepsia is a common disease in clinical service.Its etiology and pathogenesis are related to a variety of factors,and among them,gastric motility and gastrointestinal motility dysfunction are major causes.At present,diagnosis of functional dyspepsia depends maindy on the complaint of patients and no gastric motility detection method or means are effective enough to complete the diagnosis objectively.The electrical bioimpedance technique extracts information of gastric electrical activity and mechanical movement base on the recngnition of electricity-mechanism compound system and studies complicated procedure of gastric electrical activity,mechanical contraction and gastric peristalsis.The electrical bio-impedance technique has shown a promising clinical application and development prospects.

Objective In order to investigate the comlex course of electricity and mechanism of erosive gastritis(EG) and its relative factors,and to extract gastric motility feature indexes.Methods 30 volunteers of erosive gastritis were selected.The signal processing device was designed by Chongqing University of Posts and Telecommunications.By the means of spectrum analysis technic,the signals could be classified according to the dominant power and dominant frequency.Some indexes such as frequency of EGG and IGM,signal power spectrum and dynamic spectrum,the rates of rhythm and power for the normal EGG and IGM and so on could also be calculated.Results The power ratio in 2~4 cpm was 59.2?4.4,the frequency ratio was 70.4?25.5,the frequency instability coefficient was 0.182?0.059,and the power instability coefficient was 1.576?0.481.The parameters changed signifcantly between health adult and patient(P0.05).Conclusion The results of the experiments show that the method based on the synchronous measurement of EGG and IGM can provide a non-invasive way to investigate and evaluate erosive gastritis corresponding to gastrointestinal physiology and pathology conditions.

BACKGROUND:Bioimpedance method can be used to extract physiology and pathology information relative to the gastricmotility states,to investigate the courses of contraction,peristalsis,transmission and emptying of the stomach,to measure andevaluate gastric motility function.However,early studies mainly focused on the emptying of the stomach,and few studies onevaluation of gastric motility by extracting gastric motility information.OBJECTIVE:To understand the gastric motility from electricity-mechanism composite concept and to establish a noninvasive,convenience measurement method of gastric motility impedance.METHODS:Based on the characters of gastric motility impedance signal,a measurement method of impedance gastric motility isintroduced.Some foundation experiments about the gastric emptying measurement,the gastric motility compare between fastingand repast,the gastric motility comparison of healthy volunteers during different periods and some medicine effects on gastricmotility have carried out.The gastric motility measurement of the patients with functional dyspepsia and gastric motility evaluationfor the patients with erosive gastritis had been reported.RESULTS AND CONCLUSION:Using electrical bioimpedance method,according to the electrical property of the stomach tissueor the food in stomach and the change rules of the property,the physiology and pathology information relative to the gastricmotility states can be extracted,the courses of contraction,peristalsis,transmission and emptying of the stomach can beinvestigated and noninvasive measure and evaluation of gastric motility function can be realized.

According to the multi-information characteristic of pulse tracings in traditional Chinese medicine(TCM) and the dynamic analysis and identification technique of sonogram,the multi-information detection system of pulse examination was constructed by combining B-type ultrasound and flexible transducer.It made information integration of supersonic dynamic image,pressure pulse wave,photoelectric capacity pulse wave and electrocardiogram,and though the aggregate analysis of computer information processing technique,established the pulse tracings signature analysis method,formed optimized solving scheme for describing the four attributes("location,velocity,shape and potential") of pulse examination in TCM.From the multi-information data of healthy people's pulse tracings collected by this system,it can be infer that the new method of objectification of pulse examination referred in this article is feasible,and have gain the prospective effect.It provides a new method and characteristic data for the clinical study of objectification of pulse examination and teaching of TCM.