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VOLUME 3,  2003

  Measurement in Biomedicine

Titomir L.I., Mikhnev A.A., Trunov V.G., Aidu E.A.I.:
Practical ECG Mapping with Few-lead Systems: A New Approach and Mathematical Modeling
Abstract: Three versions of practical system for ECG mapping with extremely small number of leads are considered. The chosen version is primarily intended for noninvasive cardiac potential mapping on a spherical surface enclosing the heart (imaging sphere). Using the simplified mathematical models of the chest as bounded volume conductor and heart as bioelectric generator, it is shown that the lead system with 12 unipolar leads situated rather conveniently for practical investigations provides maps closely approximating the accurate maps that could be obtained by multiple-lead mapping.


Bajla I., Holländer I., Burg K.:                                                              

Improvement of Electrophoretic Gel Image Analysis      MS PowerPoint Presentation

Abstract: A novel methodology of DNA gel image analysis has been proposed that is based on 2D image processing  methods instead of previously used 1D Gaussian deconvolution. The algorithms specifically tailored to band boundary detection and image intensity homogeneity characterization have been developed. The proposed methodology involves a modified type of user interaction.


Courtney J., Burke D.P., de Paor A.M.:
Application of Digital Image Processing to Marker-free Analysis of Human Gait
Abstract: The standard method of human gait analysis in use in gait laboratories today invariably involves marker-based motion tracking systems. Although somewhat effective, these methods require accurate placement of awkward external markers. We report on an enhanced approach being researched and developed at the National Rehabilitation Hospital, Dublin based on marker-free motion tracking incorporating advanced digital image processing techniques. 


De Paor A., Burke D., O'Connor C.:
Application of the Earth's Magnetic Field and Accelerometry to the Measurement of Net Knee Extensor Torque
Abstract: This paper presents a new angle measurement and torque estimation scheme. The angle of the shin is measured with a light, inexpensive two-axis magnetoresistive bridge  (Honeywell, HMC 1022), sensing the swing of the leg through the Earth’s magnetic field. The plane of swing is magnetic north-south. The transducer is currently hard-wired to a computer, but it is planned to couple it via a miniature radio transmitter. A single-axis accelerometer (Monitran, MTN/7000-5) is mounted on the leg, below the knee at a specific distance, based on anthropomorphic data. This enables the gravity nonlinearity in the equation of leg swing to be cancelled out, linearises the observer and reduces its dynamical order.


Burke D.P., de Paor A.M.:
Signal Prediction Based on a Chaotic Attractor Model of the Electroencephalogram
Abstract: This paper presents results of a non-linear study of the human electroencephalogram to establish the feasibility of extracting non-stationary information associated with internal or external events and stimuli. By invoking chaotic time series analysis techniques, short-term predictions are made on the attractor. Comparisons with the real evolution of the EEG could in principle yield stimulus-related information. 


Tyšler M., Turzová M., Szathmáry V.:
Assessment of heart repolarization properties from body surface potential maps
Abstract: Use of activation-recovery interval (ARI) in surface ECG leads as possible indicator of changed repolarization in the underlying myocardium was studied. Model ECG data representing normal and pathological myocardium repolarization were simulated on surface of realistic inhomogeneous torso. Results of simulations suggest that shortening and prolongation of action potentials in anterior myocardial regions representing more than 6% of the heart volume can be visible in surface ARI maps while only prolongation in postero-lateral regions can be observed. Reproducibility of ARI was checked on real measurements using 32 to 192 ECG leads. Obtained ARI maps exhibited good intra-individual stability with correlation 0.89 to 0.94. From the model and experimental results it has been concluded that analysis of ARI may give some insight into the myocardium repolarization and can help to recognize tissue with changed properties namely in heart regions underlying the anterior chest. 


Rosík V., Tyšler M., Jurko Š., Rášo R., Turzová M.:
Portable system for high resolution ECG mapping
Abstract: In the paper a high resolution ECG mapping system based on personal computer or notebook equipped with fast IEEE 1284 parallel port working in ECP mode is introduced. Concept of the device enables high-resolution multi-channel ECG mapping using up to 256 ECG leads. Concept of the device and description of electrical and mechanical solution of portable 134-channel system is given.


Rášo R., Rosík V., Tyšler M.:
Multichannel Measurement of human intestinal tract electrical acticity
Abstract:  This paper presents concept of a PC based multi-channel measuring system for measurement, processing and displaying of signals of gastric electrical activity in humans. It is designed for non-invasive measurements in clinical research and practice.


Štork M.:
The System for Spiroergometric Data Measuring and Evaluation
Abstract: Exercise testing today is used not only as a diagnostic tool, but also as a technique to determine the physical  performance  characteristic  of  a  patient.  Heart  rate,  pulmonary  ventilation,  breathing frequency  and  blood  pressure  are  measured  during  the  examination.  Also  amount  of  oxygen  and carbon dioxide are measured in patient breath. From these data, many of other standard parameters are calculated by means of computer. In this paper, the systems for automatic measuring and evaluating are  described.  Application  of  these  systems  is  possible  in  work  medicine,  sport  medicine  and rehabilitation.


Chwaleba A., Kwiatos K., Nitecki G.:
Portable Microprocessor System for Tremor Signal Recording in Extrapyramidal Disease
Abstract: Tremor constitutes one of the most important symptoms of neurological disorders. However, its objective assessment is very difficult.  The methods used for objectivisation require application of such devices as piezoelectric detectors or kymographs.  The best results are achieved with the use of spectral analysis. A simple measuring set consisting of accelerometer transducers and multichannel A/D converter plugged in the ISA slot of a computer has been designed in the Institute of Fundamental Electronics of Military University of Technology, Warsaw, Poland. The equipment has been created to meet the requirement of objective tremor measurement. The set includes specialised software. 


Jakubowski J., Osowski S., Chwaleba A.:
Increasing Effectiveness of Human Hand Tremor Separation Process by Using Higher-Order Statistics
Abstract: The paper presents an attempt to discriminate the most often observed three types of human tremor with objective techniques by measuring the acceleration of the hand and by calculating some characteristic features of these time series. Different mathematical descriptions have been adopted in order to generate the features. They have come from both second and higher-order statistics.  A simple neural classifier has enabled the recognition of these three kinds of tremor with 3.6% error rate.


Tarata M., Spaepen A., Puers R.:
The Accelerometer MMG Measurement Approach, in Monitoring the Muscular Fatigue
Abstract: This research aimed to appreciate whether the mechanomyogram (MMG) may be used to monitor the muscle behaviour under fatiguing exercise. The electromyogram (EMG) and MMG were simultaneously recorded from the Biceps and from the Brachioradialis muscles, with surface electrodes - EMG, and accelerometer based transducers – MMG, from sixteen subjects. The conclusions are consistent in validating the use of the median frequency (MF) MMG to monitor the development of the muscular fatigue in the isometric isotonic exercise, at 25 % maximal voluntary contraction (MVC). The same as for the MF EMG, the MF MMG steadily decreases from the very beginning of the exercise, down to exhaustion, again demonstrating the central component of the muscular fatigue.


Halámek J., Jurák P., Kára T., Souček M.:
Transfer Function and Biosignal Analysis
Abstract: On the example of the baroreflex sensitivity the problems of transfer function in biosignal analysis are presented. Mentioned is missing standardisation, big variety of methods and supposed definitions, and missing optimization of the diagnostic contribution.


Ďaďo S., Mandys V., Šmíd R.:
Biomedical Shape Measurement for Neurotoxicity Testing
Abstract: In this paper, we present the results of the new image-based morphometric approach used to estimate toxic damage to the ganglia in alternative in vitro test. The main part of this research is devoted to multiscale and multiresolution approaches of biomedical planar shape description using continuous and discrete wavelet transform.


Roháľová M., Sykacek P., Koska M., Dorffner G.:
Detection of the EEG Artifacts by the Means of the (Extended) Kalman Filter
Abstract: This paper presents a new approach for detection of artifacts in sleep electroencephalogram (EEG)  recordings. The proposed approach is based on Kalman filter. The idea of this approach consist in  embedding the AR model into the Kalman Filter which makes possible to use such KF AR (Kalman  Filter AR) models for linear prediction of non-stationary signals. Such model can be set up to detect and follow discrete dynamic changes of the signal. For detection of the EEG artifacts we have exploited the evolution of the state noise - increase in state noise indicate the dynamic change of the signal. The evaluation of the results was done by the Receiver-Operator Characteristics (ROC) curves - in terms of the specificity and the sensitivity. For 90% of the specificity the best achieved value of the sensitivity using KF AR model was 33%. In order to achieve better results we have tried the following modification: instead of the Kalman Filter we have used extended Kalman Filter and instead of the AR model a neural network. The preliminary results look promissing: for 90% of the specificity we have achieved 65% of the sensitivity.