Robust estimation of fetal heart rate from US Doppler signals
Résumé
In utero, Monitoring of fetal wellbeing or suf-fering is today an open challenge, due to the high number of clinical parameters to be considered. An automatic mon-itoring of fetal activity, dedicated for quantifying fetal well-being, becomes necessary. For this purpose and in a view to supply an alternative for the Manning test, we used an ultrasound multitransducer muligate Doppler system. One important issue (and first step in our investigation) is the accurate estimation of fetal heart rate (FHR). An estima-tion of the FHR is obtained by evaluating the autocorrela-tion function of the Doppler signals for ills and healthiness foetus. However, this estimator is not enough robust since about 20% of FHR are not detected in comparison to a ref-erence system. These non detections are principally due to the fact that the Doppler signal generated by the fetal mov-ing is strongly disturbed by the presence of others several Doppler sources (mother' s moving, pseudo breathing, etc.). By modifying the existing method (autocorrelation method) and by proposing new time and frequency estimators used in the audio' s domain, we reduce to 5% the probability of non-detection of the fetal heart rate. These results are really encouraging and they enable us to plan the use of automatic classification techniques in order to discriminate between healthy and in suffering foetus.
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