In order to deduce the sleep stages from heart rate, we analyze the heart rate variability (HRV) with hidden Markov model (HMM) for the identification of different characters of HRV within different sleep stages. Special technique is used to compensate the individual diversity. The relationship between the sleep stage and the ultra-low frequency components of HRV is also considered. Since the detection of heart rate hardly disturbs the sleep, the proposed method provides a simple approach to evaluating the sleep stage without disturbing the sleep. Our experiments have proved that this method meets the requirements of wide applications, especially the requirement of routine use in monitoring the normal subjects' sleep.
Adult ; Electrocardiography ; Heart Rate ; Humans ; Markov Chains ; Middle Aged ; Models, Biological ; Sleep Stages ; physiology

Evoked potentials are widely used in clinical neurophysiology. The conventional analysis methods of evoked potentials are based on the waves in time domain. Analysis based on time-spatial domain will provide more information than simple time domain analysis. The existing temporal-spatial analysis methods, such as microstate, frequency domain analysis and event-related coherence, are introduced in this paper.
Evoked Potentials ; Humans ; Statistics as Topic ; methods ; Time Factors

It is estimated that epilepsy, a chronic disorder of the nervous system, affects about 0.5%-2% of the population and about 10%-50% do not respond well to current antiepileptic medications and may not be candidates for surgery. For these patients, the unpredictability of seizure onset is a major cause of disability and mortality. Therefore, anticipation of an imminent seizure would be beneficial to patients because it could provide time for the application of preventive measures to keep the risk of seizure to a minimum. This paper reviews the feasibilities, the progress, existing problems and possible applications in the field of epileptic seizure prediction.
Algorithms ; Diagnosis, Computer-Assisted ; methods ; Electroencephalography ; methods ; Epilepsy ; diagnosis ; physiopathology ; Humans ; Seizures ; diagnosis ; physiopathology ; Signal Processing, Computer-Assisted

Compared with medical ultrasonic pulse-echo imaging system, coded excitation system has the potential of higher SNR and deeper penetration depth. In this paper, the basic principle of coded excitation is introduced. Through acoustic intensity analysis, the maximum improvement of SNR of ultrasonic image with coded excitation is deduced. Then, guide lines to choose codes in ultrasonic imaging are introduced. Some codes, such as white noise, pseudo-random code, Golay code, Chirp and pseudo-chirp are described in details. At last, the applications of ultrasonic coded excitation in B-mode imaging, Doppler flow measurement, B-flow imaging and harmonics imaging are described.
Computer Simulation ; Humans ; Image Processing, Computer-Assisted ; Signal Processing, Computer-Assisted ; Transducers ; Ultrasonography ; methods

In 3D visualization of human skeleton, distinguishing bones from soft tissue in 2D CT slides is the first and most critical procedure. This article presents the methods for image pre-processing, segmentation and smoothing. 1733 CT images of human body from Visible Human Project provided by the American National Library of Medicine are treated in this paper. We use the technique of Chebyshev uniform approximation filtering for denoising and present a new simple adaptive threshold method in segmentation, which combines the similarity of consecutive slices with the region-growing method. In post-processing, we use the algorithms of mathematical morphology and multi-resolution filtering. The accuracy of segmentation is examined and certified by comparing the segmented images with the original one. The results also demonstrate a wide applicability of the method.
Algorithms ; Anatomy, Cross-Sectional ; Bone and Bones ; anatomy & histology ; diagnostic imaging ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; Phantoms, Imaging ; Skeleton ; Tomography, X-Ray Computed

With the development of the technology in medical informatics area, Health Level Seven (HL7) Standard for electronic data exchange in all healthcare environments has become a widely used standard. To bring it into practice in China, we developed an HL7 gateway. The gateway is used to connect two different medical information systems, a Hospital Information System (HIS) and a Laboratory Information Management System (LIMS), via the HL7 message exchanging. The system verified the feasibility of HL7 standard and made a good example for further research and development.
Computer Communication Networks ; standards ; Hospital Information Systems ; standards ; Software ; Systems Integration

High-intensity focused ultrasound (HIFU) thermotherapy is a promising technique for local tumor destruction of solid organs. Temperature is the important parameter which impacts the curative effects of thermotherapy. For safety and efficiency reasons, it is necessary to monitor the temperature changes inside body in real-time, non-invasively and precisely. Recently MRI methods employed for temperature monitoring during HIFU therapy have been paid more and more attentions to. This paper introduces the general principles of non-invasive temperature monitoring using MRI. The authors also review the development of this technique and point out some problems that need to be solved.
Animals ; Body Temperature ; physiology ; Humans ; Hyperthermia, Induced ; instrumentation ; Magnetic Resonance Imaging ; methods ; Monitoring, Physiologic ; methods ; Neoplasms ; therapy