title: Fetal heart rate deceleration detection using a discrete cosine transform implementation of singular spectrum analysis.
abstract: OBJECTIVE
  To develop a singular-spectrum analysis (SSA) based change-point detection algorithm applicable to fetal heart rate (FHR) monitoring to improve the detection of deceleration events.
  
  
  METHODS
  We present a method for decomposing a signal into near-orthogonal components via the discrete cosine transform (DCT) and apply this in a novel online manner to change-point detection based on SSA. The SSA technique forms models of the underlying signal that can be compared over time; models that are sufficiently different indicate signal change points. To adapt the algorithm to deceleration detection where many successive similar change events can occur, we modify the standard SSA algorithm to hold the reference model constant under such conditions, an approach that we term "base-hold SSA". The algorithm is applied to a database of 15 FHR tracings that have been preprocessed to locate candidate decelerations and is compared to the markings of an expert obstetrician.
  
  
  RESULTS
  Of the 528 true and 1285 false decelerations presented to the algorithm, the base-hold approach improved on standard SSA, reducing the number of missed decelerations from 64 to 49 (21.9%) while maintaining the same reduction in false-positives (278).
  
  
  CONCLUSIONS
  The standard SSA assumption that changes are infrequent does not apply to FHR analysis where decelerations can occur successively and in close proximity; our base-hold SSA modification improves detection of these types of event series.
authors.affiliation: Department of Biomedical Engineering, McGill University, 3775, rue University, Montréal, Québec, H3A 2B4, Canada. philip.warrick@mcgill.ca
authors.forename: P A
authors.initials: PA
authors.lastname: Warrick
authors.forename: D
authors.initials: D
authors.lastname: Precup
authors.forename: E F
authors.initials: EF
authors.lastname: Hamilton
authors.forename: R E
authors.initials: RE
authors.lastname: Kearney
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D019992:Databases as Topic; D003658:Decision Making, Computer-Assisted; D020000:Decision Support Systems, Clinical; D005323:Fetal Monitoring; D005333:Fetus / Q000502:physiology; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D009774:Obstetrics; D012815:Signal Processing, Computer-Assisted