title: Myocardial delineation via registration in a polar coordinate system.
abstract: OBJECTIVE
  Cardiovascular disease is the number one cause of premature death in the western world. Analysis of cardiac function provides clinically useful diagnostic and prognostic information; however, manual analysis of function via delineation is prohibitively time consuming. This article describes a technique for analysis of dynamic magnetic resonance images of the left ventricle using a non-rigid registration algorithm. A manually delineated contour of a single phase was propagated through the dynamic sequence.
  
  
  METHODS
  Short-axis cine magnetic resonance images were resampled into polar coordinates before all the time frames were aligned using a non-rigid registration algorithm. The technique was tested on 10 patient data sets, a total of 1,052 images were analyzed.
  
  
  RESULTS
  Results of this approach were investigated and compared with manual delineation at all phases in the cardiac cycle, and with registration performed in a Cartesian coordinate system. The results correlated very well with manually delineated contours.
  
  
  CONCLUSIONS
  A novel approach to the registration and subsequent delineation of cardiac magnetic resonance images has been introduced. For the endocardium, the polar resampling technique correlated well with manual delineation, and better than for images registered without radial resampling in a Cartesian coordinate system. For the epicardium, the difference was not as apparent with both techniques correlating well.
authors.affiliation: Division of Imaging Sciences, 5th Floor Thomas Guy House, Guy's Hospital, St Thomas' St, London SE1 9RT, UK.
authors.forename: Nicholas M I
authors.initials: NM
authors.lastname: Noble
authors.forename: Derek L G
authors.initials: DL
authors.lastname: Hill
authors.forename: Marcel
authors.initials: M
authors.lastname: Breeuwer
authors.forename: Julia A
authors.initials: JA
authors.lastname: Schnabel
authors.forename: David J
authors.initials: DJ
authors.lastname: Hawkes
authors.forename: Frans A
authors.initials: FA
authors.lastname: Gerritsen
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
mesh_terms: D000465:Algorithms; D006352:Heart Ventricles; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D017202:Myocardial Ischemia / Q000175:diagnosis*