title: Regional infarction identification from cardiac CT images: a computer-aided biomechanical approach.
abstract: OBJECTIVE
  Regional infarction identification is important for heart disease diagnosis and management, and myocardial deformation has been shown to be effective for this purpose. Although tagged and strain-encoded MR images can provide such measurements, they are uncommon in clinical routine. On the contrary, cardiac CT images are more available with lower costs, but they only provide motion of cardiac boundaries and additional constraints are required to obtain the myocardial strains. The goal of this study is to verify the potential of contrast-enhanced CT images on computer-aided regional infarction identification.
  
  
  METHODS
  We propose a biomechanical approach combined with machine learning algorithms. A hyperelastic biomechanical model is used with deformable image registration to estimate 3D myocardial strains from CT images. The regional strains and CT image intensities are input to a classifier for regional infarction identification. Cross-validations on ten canine image sequences with artificially induced infarctions were used to study the performances of using different feature combinations and machine learning algorithms.
  
  
  RESULTS
  Radial strain, circumferential strain, first principal strain, and image intensity were shown to be discriminative features. The highest identification accuracy ([Formula: see text] %) was achieved when combining radial strain with image intensity. Random forests gave better results than support vector machines on less discriminative features. Random forests also performed better when all strains were used together.
  
  
  CONCLUSIONS
  Although CT images cannot directly measure myocardial deformation, with the use of a biomechanical model, the estimated strains can provide promising identification results especially when combined with CT image intensity.
authors.affiliation: Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, USA.
authors.forename: Ken C L
authors.initials: KC
authors.lastname: Wong
authors.affiliation: Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, USA.|Institute of Biomedical Engineering, University of Oxford, Oxford, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Tee
authors.affiliation: Cardiovascular and Pulmonary Branch, NHLBI, NIH, Bethesda, MD, USA.
authors.forename: Marcus
authors.initials: M
authors.lastname: Chen
authors.affiliation: Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
authors.affiliation: Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, USA.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Summers
authors.affiliation: Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, USA. jyao@cc.nih.gov.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yao
mesh_terms: D000465:Algorithms; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D009203:Myocardial Infarction / Q000175:diagnosis*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Biomechanics; Cardiac computed tomography; Computer-aided diagnosis; Infarction identification; Machine learning; Myocardial strain estimation