Impact of pulsed-wave-Doppler velocity-envelope tracing techniques on classification of complete fetal cardiac cycles

Abstract

Fetal echocardiography is an operator-dependent examination technique requiring a high level of expertise. Pulsed-wave Doppler (PWD) is often used as a reference for the mechanical activity of the heart, from which several quantitative parameters can be extracted. These aspects suggest the development of software tools that can reliably identify complete and clinically meaningful fetal cardiac cycles that can enable their automatic measurement. Several scientific works have addressed the tracing of the PWD velocity envelope. In this work, we assess the different steps involved in the signal processing chains that enable PWD envelope tracing. We apply a supervised classifier trained on envelopes traced by different signal processing chains for distinguishing complete and measurable PWD heartbeats from incomplete or malformed ones, which makes it possible to determine the impact of each of the different processing steps on the detection accuracy. In this study, we collected 43 images and labeled 174,319 PWD segments from 25 pregnant women volunteers. By considering seven envelope tracing techniques and the 23 different processing steps involved in their implementation, the results of our study reveal that, compared to the steps investigated in most other works, those that achieve binarisation and envelope extraction are significantly more important (p < 0.05). The best approaches among those studied enabled greater than 98% accuracy on our large manually annotated dataset.

Applications of artificial intelligence in obstetrics

“…Fetal cardiac function with US is challenging due to involuntary movement of the fetus, small fetal heart, fast fetal heart rate, limited access to the fetus and the lack of experts in fetal echocardiography. Automatic calculation of fetal heart beat has been carried out through many researches using extraction of the fetal heart rate from CTG using dimensionality reduction (28,29), measuring fetal QRS complexes from maternal ECG recording using ANN (30) and pulse-wave Doppler envelope signals extracted from B-mode videos (31).…”

“…Monitoring fetal cardiac function with US is challenging due to involuntary movements of the fetus, the small fetal heart, the fast fetal heart rate, limited access to the fetus, and the lack of experts in fetal echocardiography. Automatic calculation of the fetal heartbeat has been carried out in many studies that have extracted the fetal heart rate from CTG using dimensionality reduction [ 38 , 41 ] or measured fetal QRS complexes from maternal ECG recordings using ANN [ 42 ] and pulse-wave Doppler envelope signals extracted from B-mode videos [ 43 ]. For cases with congenital heart anomalies, an intelligent navigation method referred to as "FINE" was developed and this can detect four types of abnormalities [ 44 ].…”