title: An open-source framework for stress-testing non-invasive foetal ECG extraction algorithms.
abstract: Over the past decades, many studies have been published on the extraction of non-invasive foetal electrocardiogram (NI-FECG) from abdominal recordings. Most of these contributions claim to obtain excellent results in detecting foetal QRS (FQRS) complexes in terms of location. A small subset of authors have investigated the extraction of morphological features from the NI-FECG. However, due to the shortage of available public databases, the large variety of performance measures employed and the lack of open-source reference algorithms, most contributions cannot be meaningfully assessed. This article attempts to address these issues by presenting a standardised methodology for stress testing NI-FECG algorithms, including absolute data, as well as extraction and evaluation routines. To that end, a large database of realistic artificial signals was created, totaling 145.8 h of multichannel data and over one million FQRS complexes. An important characteristic of this dataset is the inclusion of several non-stationary events (e.g. foetal movements, uterine contractions and heart rate fluctuations) that are critical for evaluating extraction routines. To demonstrate our testing methodology, three classes of NI-FECG extraction algorithms were evaluated: blind source separation (BSS), template subtraction (TS) and adaptive methods (AM). Experiments were conducted to benchmark the performance of eight NI-FECG extraction algorithms on the artificial database focusing on: FQRS detection and morphological analysis (foetal QT and T/QRS ratio). The overall median FQRS detection accuracies (i.e. considering all non-stationary events) for the best performing methods in each group were 99.9% for BSS, 97.9% for AM and 96.0% for TS. Both FQRS detections and morphological parameters were shown to heavily depend on the extraction techniques and signal-to-noise ratio. Particularly, it is shown that their evaluation in the source domain, obtained after using a BSS technique, should be avoided. Data, extraction algorithms and evaluation routines were released as part of the fecgsyn toolbox on Physionet under an GNU GPL open-source license. This contribution provides a standard framework for benchmarking and regulatory testing of NI-FECG extraction algorithms.
authors.affiliation: Institute of Biomedical Engineering, Faculty of Electrical and Computer Engineering, Technische Universität Dresden, Dresden, Germany. Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
authors.forename: Fernando
authors.initials: F
authors.lastname: Andreotti
authors.forename: Joachim
authors.initials: J
authors.lastname: Behar
authors.forename: Sebastian
authors.initials: S
authors.lastname: Zaunseder
authors.forename: Julien
authors.initials: J
authors.lastname: Oster
authors.forename: Gari D
authors.initials: GD
authors.lastname: Clifford
mesh_terms: D022126:Access to Information; D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D019992:Databases as Topic; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D005324:Fetal Movement / Q000502:physiology; D005333:Fetus; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D020407:Internet; D008955:Models, Cardiovascular; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012984:Software; D014590:Uterine Contraction / Q000502:physiology