The RITS Conference: A Major Event of Biomedical Engineering in France

International audienceResearch in Imaging and HealTh TechnologieS (RITS) is a French scientific meeting dedicated to Biomedical Engineering. This biennial event has given rise to four special issues of IRBM since 2009. The present issue collects some research works presented by young researchers (first author being less than 32 years old). All of them submitted a full paper (instead of a long abstract) to the meeting in order to participate in the SFGBM competition. All the published papers followed the standard reviewing process

Sources of Bias in Synchronization Measures and how to Minimize Their Effects on the Estimation of Synchronicity: Application to the Uterine Electromyogram

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Preterm labour detection by use of a biophysical marker: the uterine electrical activity

<p>Abstract</p> <p>Background</p> <p>The electrical activity of the uterine muscle is representative of uterine contractility. Its characterization may be used to detect a potential risk of preterm delivery in women, even at an early gestational stage.</p> <p>Methods</p> <p>We have investigated the effect of the recording electrode position on the spectral content of the signal by using a mathematical model of the women's abdomen. We have then compared the simulated results to actual recordings. On signals with noise reduced with a dedicated algorithm, we have characterized the main frequency components of the signal spectrum in order to compute parameters indicative of different situations: preterm contractions resulting nonetheless in term delivery (i.e. normal contractions) and preterm contractions leading to preterm delivery (i.e. high-risk contractions). A diagnosis system permitted us to discriminate between these different categories of contractions. As the position of the placenta seems to affect the frequency content of electrical activity, we have also investigated in monkeys, with internal electrodes attached on the uterus, the effect of the placenta on the spectral content of the electrical signals.</p> <p>Results</p> <p>In women, the best electrode position was the median vertical axis of the abdomen. The discrimination between high risk and normal contractions showed that it was possible to detect a risk of preterm labour as early as at the 27th week of pregnancy (Misclassification Rate range: 11–19.5%). Placental influence on electrical signals was evidenced in animal recordings, with higher energy content in high frequency bands, for signals recorded away from the placenta when compared to signals recorded above the placental insertion. However, we noticed, from pregnancy to labour, a similar evolution of the frequency content of the signal towards high frequencies, whatever the relative position of electrodes and placenta.</p> <p>Conclusion</p> <p>On human recordings, this study has proved that it is possible to detect, by non-invasive abdominal recordings, a risk of preterm birth as early as the 27th week of pregnancy. On animal signals, we have evidenced that the placenta exerts a local influence on the characteristics of the electrical activity of the uterus. However, these differences have a small influence on premature delivery risk diagnosis when using proper diagnosis tools.</p

Nonlinear estimation of coupling and directionality between signals: Application to uterine EMG propagation.

International audienceUnderstanding the direction and quantity of information flowing in a complex system is a fundamental task in signal processing. Several measures have been proposed to detect the quantity of synchronization and the directionality between time series and in physiological data. In this paper we use two methods that are widely used in synchronization and directionality analysis: Nonlinear correlation coefficient (h(2)) and the general synchronization (H). The performances of both methods were tested on four dimensional coupled synthetic nonlinear Rössler models. They were then applied to a single real labor contraction uterine EMG burst with the aim of using them to detect synchronization and to plot the map of direction of information flow between the whole signal channels. The results on synthetic signal show a slight superiority of H over h(2). The results obtained on a single contraction are encouraging for the future use of these tools for resolving the open question of the directionality of uterine contractions and may provide a way of finding their source loci

Utilisation de la transformée en ondelettes non décimée pour le débruitage du signal électrohystérographique utérin

Le signal électrohystéographique (EHG) représente l'activité utérine de la femme pendant la grossesse. La théorie des ondelettes est bien adaptée au débruitage de ce signal non stationnaire, corrompu par des bruits électroniques, électromagnétiques et physiologiques (par exemple l'électrocardiogramme maternel). A cause de la décimation, la traditionnelle décomposition orthogonale ne conserve que les coefficients nécessaires et suffisants pour une reconstruction parfaite. Cependant, la redondance d'information issue d'une transformée non décimée apparaît aujourd'hui précieuse pour le débruitage. Nous proposons une technique de débruitage, appliquée à l'EHG, utilisant l'algorithme à trous, avec des filtres miroirs en quadrature. Dans cette méthode, nous prenons en compte la redondance d'information dans l'estimation du seuil de débruitage

Détection et classification d'événements en représentation multidimensionnelle. Application sur l'EMG utérin

L'EMG utérin peut être représenté par un processus AR où plusieurs événements sont superposés. Dans ce cas, la détection peut être faite en utilisant des algorithmes de détection classiques. Cependant, l'algorithme de classification doit prendre en compte les formes spécifiques de ces événements superposés. Dans ce travail, la classification est basée sur la décomposition multi-échelle et sur le test multihypothèse. Après détection utlisant le modèle AR adaptatif, le signal est décomposé en plusieurs échelles et classifié suivant une matrice de variance-covariance calculée à partir de la décomposition multiéchelle. Cet approche aboutit à deux retards différents pour la détection et la classification. Ils dépendent du seuil de détection et du temps d'estimation de la matrice de variance covariance, respectivement

Electrohysterographic characterization of the uterine myoelectrical response to labor induction drugs

[EN] Labor induction is a common practice to promote uterine contractions and labor onset. Uterine electrohysterogram (EHG) has proved its suitability for characterizing the uterus electrophysiological condition in women with spontaneous labor. The aim of this study was to characterize and compare uterine myoelectrical activity during the first 4h in response to labor induction drugs, Misoprostol (G1) and Dinoprostone (G2), by analyzing the differences between women who achieved active phase of labor and those who did not (successful and failed inductions). A set of temporal, spectral and complexity parameters were computed from the EHG-bursts. As for successful inductions, statistical significant and sustained increases with respect to basal period were obtained for EHG amplitude, mean frequency, uterine activity index (UAI) and Teager, after 60¿ for the G1 group; duration, amplitude, number of contractions and UAI for the G2 group, after 120¿. Moreover, Teager showed statistical significant and sustained differences between successful and failed inductions (1.43±1.45 µV2.Hz2.105 vs. 0.40±0.26 µV2.Hz2.105 after 240¿) for the G1 group, but not in the G2 group, probably due to the slower pharmacokinetics of this drug. These results revealed that EHG could be useful for successful induction prediction in the early stages of induction, especially when using Misoprostol.This research project was supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (DPI2015-68397-R) and by the company Bial SA.Benalcazar-Parra, C.; Ye Lin, Y.; Garcia Casado, J.; Monfort-Orti, R.; Alberola Rubio, J.; Perales Marín, AJ.; Prats-Boluda, G. (2018). Electrohysterographic characterization of the uterine myoelectrical response to labor induction drugs. Medical Engineering & Physics. 56:27-35. https://doi.org/10.1016/j.medengphy.2018.04.002S27355