title: Quantitative myocardial infarction on delayed enhancement MRI. Part I: Animal validation of an automated feature analysis and combined thresholding infarct sizing algorithm.
abstract: OBJECTIVE
  To develop a computer algorithm to measure myocardial infarct size in gadolinium-enhanced magnetic resonance (MR) imaging and to validate this method using a canine histopathological reference.
  
  
  METHODS
  Delayed enhancement MR was performed in 11 dogs with myocardial infarction (MI) determined by triphenyltetrazolium chloride (TTC). Infarct size on in vivo and ex vivo images was measured by a computer algorithm based on automated feature analysis and combined thresholding (FACT). For comparison, infarct size by human manual contouring and simple intensity thresholding (based on two standard deviation [2SD] and full width at half maximum [FWHM]) were studied.
  
  
  RESULTS
  Both in vivo and ex vivo MR infarct size measured by the FACT algorithm correlated well with TTC (R = 0.95-0.97) and showed no significant bias on Bland Altman analysis (P = not significant). Despite similar correlations (R = 0.91-0.97), human manual contouring overestimated in vivo MR infarct size by 5.4% of the left ventricular (LV) area (equivalent to 55.1% of the MI area) vs. TTC (P < 0.001). Infarct size measured by simple intensity thresholdings was less accurate than the proposed algorithm (P < 0.001 and P = 0.007).
  
  
  CONCLUSIONS
  The FACT algorithm accurately measured MI size on delayed enhancement MR imaging in vivo and ex vivo. The FACT algorithm was also more accurate than human manual contouring and simple intensity thresholding approaches.
authors.affiliation: Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, National Institutes of Health/DHHS, 10 Center Drive, Bethesda, MD 20892, USA.
authors.forename: Li-Yueh
authors.initials: LY
authors.lastname: Hsu
authors.forename: Alex
authors.initials: A
authors.lastname: Natanzon
authors.forename: Peter
authors.initials: P
authors.lastname: Kellman
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Hirsch
authors.forename: Anthony H
authors.initials: AH
authors.lastname: Aletras
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Arai
mesh_terms: D000465:Algorithms; D000818:Animals; D003287:Contrast Media; D004285:Dogs; D019786:Gadolinium DTPA; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009203:Myocardial Infarction / Q000473:pathology*; D015588:Observer Variation; D013778:Tetrazolium Salts
chemical_list: D003287:Contrast Media; D013778:Tetrazolium Salts; C009591:triphenyltetrazolium; D019786:Gadolinium DTPA