Wyniki wyszukiwania - BazTech

1

Ekstrakcja charakterystycznych cech sygnału elektrogastrograficznego przy wykorzystaniu transformaty falkowej

Świerczyński Z., Guszkowski T.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 1

137-139

PL

Celem niniejszego referatu jest przedstawienie problemu przetwarzania i analizy sygnałów elektrycznej aktywności układu pokarmowego (lub inaczej gastrycznej) znanych jako EGG (ElectroGastroGraphic). Sygnały te rejestrowane mogą być w sposób inwazyjny oraz coraz częściej w sposób nieinwazyjny przy pomocy powierzchniowych elektrod naskórnych. W rejestracjach inwazyjnych wyróżnia się m.in. składowe w postaci elektrycznej aktywności sterującej (ECA), które w powierzchniowych zapisach EGG są trudno rozpoznawalne. Dzięki odpowiednim narzędziom takim jak transformata falkowa możliwa jest rekonstrukcja składowych ECA z zapisów EGG tak aby przypominały składowe obserwowane w zapisach inwazyjnych. Przedstawiają to zamieszczone tutaj wyniki. W zaproponowanym kształcie nie jest to jeszcze metodyka doskonała ale opiera się na automatycznym i adaptacyjnym algorytmie, więc jej wyniki można traktować jako obiektywne, przynajmniej na poziomie braku czynnika ludzkiego.

EN

The aim of the article is to present the problem of processing and analysis of electrical activity of the gastric system, known as Elecrogastrography (EGG). The signals can be acquired in an invasive or noninvasive way with cutaneous electrodes. In the invasive recordings one can see components in form of electrical control activity (ECA), that are hardly to recognize in cutaneous EGG. Thanks to adequate tools, as wavelet transform, it is possible to reconstruct ECA from EGG recordings in the way that processed EGG are similar to those observed in invasive recordings. The described results of the work are preliminary, but they tend to be promising.

2

Continuous wavelet transform as effective tools for detecting motion artefacts in electrogastrographical signals

Mika B., Tkacz E., Kostka P. S.

Journal of Medical Informatics & Technologies

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2011

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Vol. 18

59--68

EN

The cutaneous recording of gastric myoelectrical activity of the stomach known as electrogastrography (EGG) seems to be the promising tool for the non-invasive assessment of gastric motility. Unfortunately the EGG recording is usually severely contaminated both by motion artefacts and endogenous biological noise source. In order to use EGG signals as reliable diagnostic tool it is necessity to look for the effective artefacts removal methods. In this paper Continuous Wavelet Transform (CWT) was applied for detection motion artefacts from the EGG data. The set of own mother wavelets extracted directly from EGG signal was created and applied for detecting motion artefacts from one channel EGG recording. The results was compared with the effects obtained by using standard mother wavelets. The proposed method based on CWT with own mother wavelet presents very good performance for detecting motion artefacts from the EGG data.

3

Independent component analysis and adaptive filtering as successful tools for an improvement of normogastric rhythm extraction in electrogastrographic signals

Tkacz E., Mika B.

Journal of Medical Informatics & Technologies

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2010

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Vol. 16

27--34

EN

The aim of this study was to investigate the possibility of combining two methods: Independent Component Analysis (ICA) and Adaptive Signal Enhancement for the improvement of normogastric rhythm extraction from multichannel recording of electrogastrographic signals (EGG). Unfortunately the electrogastrogram, is a transcutaneous measurement of gastric electrical activity, does not contain pure signal but usually is a sort of mixture from both electrical activity of stomach as well as other organs surrounding it and random noise. In order to benefit the diagnostic power of multichannel recording of EGG, which can provide deeper understanding of gastric disorders, it is necessity to extract gastric slow wave in each channel. One of the parameters, which are analyzed and require proper registration is so called normogastric rhythm. According to the literature, the normogastric rhythm should cover around 70% of rhythmic behavior of signal for a healthy man. Proper extraction of basic 3-cpm normogastric rhythm in each channel is a subject of this paper. Independent Component Analysis is applied for extracting the reference signal for adaptive filtering what next result in obtaining less contaminated signal in each channel. Analysis has been perform for two postprandial phases with five minutes break between them. In both mention cases proposed procedure gives a promising results.

4

Application of SOM in classification of EGG signals

Świerczyński Z., Guszkowski T.

Metrology and Measurement Systems

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2006

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Vol. 13, nr 3

279-287

EN

The report presents problems associated with computer aided gastric diagnosis. The subject of the study are electrogastrographic (EGG) signals (non-invasively measured electrical signals generated by the human stomach). The signals were digitally recorded and then parametrized, with linear autoregressive models (AR). The data and parametrization method used in the study were the same as used by the authors in the previous study; therefore here they are only shortly described. The sets of numbers, obtained by these means, were treated as information vectors, and classified with the Self Organizing Map (SOM) classifier. The structure and parameters of the algorithm used for classification of the parametrized EGG data are described. The final efficiency of the whole system (SOM classifier with the parametrization method applied), reaching 80%, is promising. It is similar to the results of other classifiers. The ways to improve the effectiveness are also outlined.

PL

Praca przedstawia problemy związane z komputerowo wspomaganym diagnozowaniem układu pokarmowego. Obiektem badań są tutaj sygnały elektrogastrograficzne - EGG (nieinwazyjnie mierzone sygnały elektryczne generowane przez żołądek człowieka). Sygnały te zostały zarejestrowane cyfrowo a następnie poddane parametryzacji przy pomocy liniowego modelu autoregresyjnego AR. Dane oraz metoda parametryzacji użyta w przedstawionych badaniach zostały opisane w poprzednich pracach autorów, więc tutaj ujęte są jedynie w zarysie. Zestawy liczb otrzymane w wyniku parametryzacji potraktowane zostały jako wektor parametrów i sklasyfikowane przy pomocy klasyfikatora opartego na samoorganizujących się mapach (SOM). W pracy przedstawiono strukturę i parametry użytego algorytmu. Ostateczna skuteczność całego systemu (tj. klasyfikatora SOM oraz zastosowanej metody parametryzacji) wyniosła 80%, co jest wynikiem obiecującym i bardzo podobnym do tych jakie osiągnięto przy zastosowaniu innych metod klasyfikacji. Praca przedstawia również zarys metod poprawy efektywności opisanego systemu.

5

Application of SVM in computer aided gastric diagnostic system

Świerczyński Z., Mazur J.

Biocybernetics and Biomedical Engineering

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2004

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Vol. 24, no. 4

19-30

EN

In the paper computer aided stomach diagnosis problems are presented. The subject of the study is electrical signal generated by human stomach and called electrogastrographic (EGG) signal. The non-invasively measured signals were subjected to parametrization, which was performed with one of the time series modelling methods, with linear autoregressive models (AR). Then the obtained sets of numbers were classified with the Support Vector Machine (SVM), which is a relatively new pattern recognition technique and is based on the idea of structural risk minimization, The structure and parameters of algorithm used for classification of the parameterized EGG data are described. The finally obtained effectiveness of the whole system (SVM with the parametrization method applied), amounting to 81%, is promising and, according to the authors' analysis can be improved. The ways of improving of the effectiveness are also outlined in the conclusions.

6

The use of laryngograph in assessing phonatory disfunctions of the larynx

Kulinowski W., Zielińska J., Zagólski O.

Journal of Medical Informatics & Technologies

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2000

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Vol. 1

BI 111--119

EN

Laryngograph Processor PCLX can be used to assess phonatory function of the larynx and the degree of impairment of the glottis closure in case of vocal fold palsy. The laryngograph measures electric impedance between two electrodes located on both sides of the neck at the level of thyroid cartilage of the larynx. The impedance is lowest when vocal folds are in median position and the glottis is closed. The device can eliminate the influence of other impedances within the neck on electroglottographic (EGG) tracings thanks to conducting rings surrounding the electrodes. EGG wave can be divided into three phases. The rapid increase of impedance at the beginning of the glottal cycle is caused by closing of the glottis and is called closing phase. It is followed by opening phase being result of separation of the vocal folds and opening of the glottis. Next phase is called open phase. This part of the wave corresponds to the time when glottis is open. The laryngograph is supplied with electrodes and a microphone. The EGG tracings can be acquired and analyzed in PCwave and PCpitch views. SpeechStudio 1.04 software, operating in Microsoft Windows environment, can also measure irregularity of the frequency of the glottal cycles. The irregularity is expressed in percent. A patient must repeat the test list a few times. The list is composed of single utterances of vowels, single words and phrases. A case of patient with left vocal fold palsy after viral infection of the upper respiratory airways is presented. The EGG wave at first measurement shows slightly prolonged closing phase and irregularity of 38%. After three months of treatment and follow-up the shape of the wave was closer to normal with irregularity of 14%. The patient’s voice was clinically normal. The aryngograph is useful tool for predicting clinical outcome in patients with vocal fold paresis.

PL

Do oceny funkcji fonacyjnej krtani stosuje się urządzenie zwane laryngografem. Znajduje ono zastosowanie w badaniu stopnia upośledzenia czynności głośni w przypadkach porażeń fałdów głosowych. Omówiono zasady działania laryngografu oraz sposób wykonania badania i interpretacji jego wyników. Przedstawiono przypadek chorego leczonego laryngologicznie z powodu porażenia lewego fałdu głosowego, powstałego w wyniku infekcji grypowej.