Objective To research some parameters' influence on signal-to-noise ratio (SNR) of MR. Methods Magphan phantom was used to do experiments on 1.5T, 0.5T and 0.23T MRI. Scan parameters such as NEX, scan matrix and slice thickness were altered.Evaluate whether the change of SNR varied with parameter to be in accordance with the SNR law.Results (1) When spin echo pulse applied and NEX changed, the results of high field device A and B weren't in accordance with SNR theory, and high filed device C and low field device F were in accordance with SNR theory. When fast spin echo pulse applied and NEX changed, the result of device B was in accordance with SNR theory. (2) When scan matrix changed, measured value was lower than ideal value for little matrix, and vice versa. (3) The measured value was very closely to ideal value for little slice thickness. When slice thickness exceed 5 mm, the difference between the measured value and ideal value was significance.Conclusion Based on the SNR theory, the user of MRI should consider the running characteristic of MR system to select scan parameters.

Animals ; Chiroptera ; virology ; Coronavirus ; classification ; genetics ; isolation & purification ; Coronavirus Infections ; transmission ; virology ; Databases, Genetic ; Genome, Viral ; Humans ; Male ; Middle Aged ; Middle East ; Phylogeny ; SARS Virus ; classification ; genetics ; isolation & purification ; Severe Acute Respiratory Syndrome ; virology

In many medical instrumentation systems, there exists a long distance between manipulation platform and host unit. Wireless data transferring between the platform and the host could be a feasible way to set parameters. This paper introduces wireless transmitter and receiver circuit based on encoder chip PT2262 and decoder chip PT22720, and presents some typical applications in medical instrument development.

Objective To apply chaos characteristics to prediction of the unilateral mastication.Methods The paper calculated the Largest Lyapunov Exponent of the masseter muscle of some males and females with a method from small data sets,which then was processed by reusable two-factor analysis of variance.Results The results shows that the signal of the masseter muscle has chaos characteristics,the male's Largest Lyapunov Exponent is higher that the female's,and the chaos degree of the masseter muscle on both sides is consistent nearly.Conclusion The Largest Lyapunov Exponent can be used to characterize the signal of the masseter muscle.Comparative Analysis of the Largest Lyapunov Exponent on both sides can be used as reference when to predict and diagnose the unilateral mastication.

In this article,a new approach tosleep analysis based on fuzzy prediction theory is described.This article gives a general introduction todetection and processing of biological signals with LabVIEW technique.The designed fuzzy measurement system is applied tofuzzy prediction analysis of physiological signals.The experiment results show that our method of analysis is correct.SoLabVIEW-based fuzzy prediction analysis is more helpful for early diagnosis,monitoring and prognosis assessment of some diseases.The method might reflect the sleep state of SASpatient.

Based on the high-dimension chaos characteristics of electroencephalogram(EEG) and the analysis by the multi-variable state space reconstruction,better estimation of the correlative dimension can be obtained by dividing the brain into two parts and using eight EEG channels as the reconstruction samples.Lorenz system was firstly tested by request of the amount of data to test the feasibility of the algorithms.After Comparing the high-dimension data of the EEG of epileptic patients with the results of control subjects,it is indicated that the multi-variable state space reconstruction is applicable in short time noise-containing time sequences to obtain reliable results and can free the researchers from the hard choice of delay time and embedding dimension.

Objective To establish a loop-mediated isothermal amplification (LAMP) assay for rapid detection of the West Nile virus (WNV).Methods WNV genome (position nt 1 021 to nt 1 240) was synthesized by a PCR-based gene synthesis method.The synthetic fragments included 6 pairs of LAMP primer recognizing 8 primer sites of WNV genome.The LAMP gene amplification was carried out using a real-time PCR system at 63℃ for 60 min,then the amplification was terminated at 80℃ after 2 min.The amplification products were observed by agarose gel electrophoresis.The sensitivity and specificity of LAMP assay were compared with those of conventional PCR.Results The LAMP assay took less than 20 min,and the amplification product took on a ladder-like electrophoresis pattern.The sensitivity of LAMP assay was 10-fold higher than that of conventional PCR,and the detection limit of LAMP was 9.23 copies/?l.The specificity of WNV-specific LAMP assay was demonstrated by the negative amplification results from dengue virus and Japanese encephalitis virus,both were closely related members of the Flavivirus family.Conclusion LAMP assay is rapid,cost-effective,highly sensitive and specific in detecting genes of interest,and is of great significance for WNV surveillance,especially for grass root units and on-sport surveillance.

The development and progression of atherosclerosis and thrombosis are closely related to changes of hemodynamics parameters. Ultrasonic pulse wave Doppler technique is normally used for noninvasively blood flow imaging. However, this technique only provides one-dimensional velocity and depends on the angle between the ultrasound beam and the local velocity vector. In this study, ultrasonic particle image velocimetry method was used to assess whole field hemodynamic changes in normal blood vessels. By using the polynomial fitting method, we investigated the velocity gradient and assessed the shear in different blood flow velocity of 10 healthy rats. It was found that using four polynomial fitting could result in optimal measurement results. The results obtained by ultrasonic particle image velocimetry accorded with the results obtained using Doppler technique. The statistical average of cyclical vessel wall shear stress was positively related to the locational mean velocity. It is proven that ultrasonic particle image velocimetry method could be used to assess directly the real-time whole field hemodynamic changes in blood vessels and was non-invasively, and should be a good prosperous technique for monitoring complex blood flow in stenotic ar- teries.
Algorithms ; Animals ; Arteries ; diagnostic imaging ; pathology ; Blood Flow Velocity ; Echocardiography, Doppler ; Hemodynamics ; Models, Cardiovascular ; Rats ; Rheology ; Stress, Mechanical ; Ultrasonics

Objective To evaluate reoperations for benign bile duct strictures after a prewousRoux-en-Y hepaticojejunostomy.Methods Clinical date of 28 patients with previous reconstruction of Roux-en-Y hepaticojejunostomy for benign bile duct strictures were retrospectively analyzed.For data staftstical analysis t-test and stepwise logistic regression analysis were used.Results Reoperative surgery was performed for residual biliary stones with bile duct stricture in 10 cases(35.7%),simple anastomotic stricture of hepaticojejunostomy in 11 cases(39.3%),remained biliary stricture after initial rear in 6 cases (21.4%).anastomotic leakage with duodenal leakage in one case(3.6%).Mode of reoperation:18 cases (64.3%)underwent hepatic lobectomy with Roux-en-Y hepaticojejunostomy,liver splitting approach to Roux-en-Y hepaticojejunostomy in 5 cases(17.9%),right hemihepatectomy in one case(3.6%),resection of anastomotic stenosis involved segment and Roux-en-Y hepaticojejunostomy in one case(3.6%),abdominal drainage and duodenum fistulization and jejunum ostomy in one case(3.6%),choledocholithotomy with T-tube drainage in 2 cases(7.1%);Thirteen patients(46.4%)developed postoperative complications.Conclusion Biliary tract stenosis remains the main cause for reoperation in patients undergoing a faeled reconstruction.Wide and patent biliary tract drainage and reconstruction somenmes necessitate a hepatic lobectomy.

This paper introduces a programming cardiac trigger apparatus used for the study of quantitative measurement of myocardial blood flow with myocardial contrast echocardiography.The design of hardware circuit based on MCU and the scheme of software based on Keil C51 are mainly discussed.With stable and reliable working,this apparatus provides a kind of technical support for the study of quantitative measurement of myocardial blood flow with continuous intravenous injection of sonicated microbubbles.