Synchronization between EMG at Different Uterine Locations Investigated Using Time-Frequency Ridge Reconstruction: Compa
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Research Article Synchronization between EMG at Different Uterine Locations Investigated Using Time-Frequency Ridge Reconstruction: Comparison of Pregnancy and Labor Contractions J´er´emy Terrien,1 Thora Steingrimsdottir,2 Catherine Marque,3 and Brynjar Karlsson1, 4 1 School
of Science and Engineering, Reykjavik University, 103 Reykjavik, Iceland of Obstetrics and Gynecology, Landspitali University Hospital, 101 Reykjavik, Iceland 3 UMR CNRS 6600, Biom´ ecanique et Bio-ing´enierie, Universit´e de Technologie de Compi`egne, 60205 Compi`egne, France 4 Institute of Physiology, University of Iceland, 101 Reykjavik, Iceland 2 Department
Correspondence should be addressed to J´er´emy Terrien, [email protected] Received 21 December 2009; Accepted 28 April 2010 Academic Editor: Syed Ismail Shah Copyright © 2010 J´er´emy Terrien et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The extraction of the frequency components of a signal can be useful for the characterization of the underlying system. One method for isolating a frequency component of a signal is by the extraction and reconstruction of the local maxima or ridge of its time-frequency representation. We compare here the performances of two well-known ridge reconstruction methods, namely the Carmona and Marseille methods, on synthetic signals as well as real electrohysterogram (EHG). We show that Carmona’s method presents lower reconstruction errors. We then used the separately reconstructed frequency components of the EHG independently for labor prediction using a synchronization measure. We show that the proposed synchronization parameters present similar prediction rate to classical parameters obtained directly from the time-frequency representation but also seem to provide information complementary to the classical parameters and may thus improve the accuracy in labor prediction when they are used jointly.
1. Introduction Preterm labor is an important public health problem in Europe and other developed countries as it represents nearly 7% of all births. It is the main cause of morbidity and mortality of newborns. One of most promising biophysical markers of preterm labor threat is the electrical activity of the uterus, the uterine electromyogram [1]. The uterine electromyogram recorded externally in women, the electrohysterogram (EHG), has been proven to be representative of uterine contraction. The analysis of such a signal may allow the prediction of preterm labor as soon as the 28th week of gestation (WG) [2, 3]. However, the physiological phenomena underlying preterm labor remain poorly understood. It is well known that uterine contractility depends on the excitability of uterine myocytes, but also on the propagation of the electrical activity to the whole uterus [4]. These two aspects of uterine contraction mechanisms,
excitability and propagation, both influence the spectral co
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