Recent Advances in Doppler Signal Processing and Modelling Techniques for Fetal Monitoring

Fetal health is critical to peri- and post-natal normality with consequences for general health in later life. However, even when pregnancies show no identifiable risks, 100% healthy births do not happen. Doppler based fetal cardiac assessment provides significant information about the fetal development and well-being. Cardiotocography (CTG), which is a record of the doppler based fetal heart rate (FHR) and uterine contraction activity measured via a transducer on the maternal abdomen, is commonly used for fetal welfare evaluation. However, CTG has a very poor specificity because sometimes abnormal variability in doppler signal based fetal heart rate may not necessarily represent a compromised fetus. As reported in several recent studies, the indices adopted in CTG do not appear to have brought about a reduction in fetal mortalities. Fetal movements, particularly in early stage fetuses, often result in doppler signal loss and consequent mis-diagnosis. The Royal College of Obstetrics and Gynecologists report suggests that more advanced processing of fetal doppler signals should be part of a reliable heart anomaly screening.Consequences resulting from fetal hypoxia, congenital heart defects, arrhythmia and fetal growth restriction manifest in fetal heart activity. For example the interval between the onset of the R peak of fetal ECG and the start of ventricular ejection (i.e., the opening of aortic valve) and the interval from opening to closure of aortic valve, are known to be very sensitive indicators of fetal myocardial performance. However, given the strong non-stationarities in doppler signals, the challenge of reliably estimating fetal cardiac events’ timings under fetal movements still exists. This reliability is critical to any discrimination of heart-abnormal fetuses from normal ones.

Topics (not limited to) of interests:

1) Recent advances in fetal doppler ultrasound signal processing and modelling
2) A variety of applications of one-dimensional doppler ultrasound signals in assessing fetal development and well-being.
3) Applications of Computational Intelligent techniques in estimating the fetal heart rate and cardiac valve timings
4) Issues related to doppler signal quality and its non-stationarities