ABSTRACT
Fetal activity is an important indicator of fetal well-being. It is proposed to assess this activity using the pulsed wave Doppler method to collect fetal activity data and dedicated software for on-line processing. The system, addressed to 3rd trimester pregnancies, provides information on presence of pseudobreathing, the heart rate trace, the fetal movement trace, the movement velocity spectrogram, histograms of the velocity and acceleration of both the body movements and pseudobreathing, parameters of these histograms (mean values, standard deviations, shape descriptors), and cumulative counts of the velocity histograms. These parameters form the feature vector of the fetal activity. The system was validated by simultaneous echographic and cardiotocographic recordings and during oxytocin challenge tests. Feature vectors obtained from 1h recordings in 61 pregnancies were submitted to multivariate analysis of variance. Activity patterns of physiological cases and "borderline pathologies" were discriminated using reduced feature vectors, containing cumulative counts of velocity histograms.
Subject(s)
Cardiotocography/methods , Fetal Movement , Heart Rate, Fetal , Ultrasonography, Prenatal/methods , Female , Humans , Pregnancy , Pregnancy Complications/diagnosis , Pregnancy Complications/metabolism , Pregnancy Trimester, Third , Ultrasonography, Doppler/methodsABSTRACT
A method for automatic detection of fetal breathing movements has been proposed, based on the time-frequency structure of the corresponding continuous wave ultrasonic Doppler signals. The method uses spectral analysis of the envelope of the directional Doppler signal and cross-correlation analysis of both directional envelopes. Detection rule comprises the following criteria: presence of the peak in the envelope spectrum and of the adequate signal level in the frequency range corresponding to the fetal breathing rhythm, the peak value and the position limits of the peak of the cross-correlation coefficient of the both directional envelopes. The effect of the criteria setting on the rule performance and the tradeoff between the specificity and sensitivity was investigated. The rule is most sensitive to the threshold value of the cross-correlation coefficient of the envelopes. The limits of the position of this peak are crucial for the distinction between the breathing episodes and hiccups. The optimal settings of the criteria, resulting in average sensitivity and specificity exceeding, respectively, 0.70 and 0.80, are proposed.
Subject(s)
Fetal Monitoring/instrumentation , Fetal Movement , Signal Processing, Computer-Assisted , Ultrasonography, Doppler/instrumentation , Ultrasonography, Prenatal/instrumentation , Algorithms , Automation , Female , Fetal Monitoring/methods , Humans , Pregnancy , Reproducibility of Results , Respiration , Sensitivity and Specificity , Software , Time Factors , Ultrasonography, Doppler/methods , Ultrasonography, Prenatal/methodsABSTRACT
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