title: MRI-based strain and strain rate analysis of left ventricle: a modified hierarchical transformation model.
abstract: BACKGROUND
  Different from other indicators of cardiac function, such as ejection fraction and transmitral early diastolic velocity, myocardial strain is promising to capture subtle alterations that result from early diseases of the myocardium. In order to extract the left ventricle (LV) myocardial strain and strain rate from cardiac cine-MRI, a modified hierarchical transformation model was proposed.
  
  
  METHODS
  A hierarchical transformation model including the global and local LV deformations was employed to analyze the strain and strain rate of the left ventricle by cine-MRI image registration. The endocardial and epicardial contour information was introduced to enhance the registration accuracy by combining the original hierarchical algorithm with an Iterative Closest Points using Invariant Features algorithm. The hierarchical model was validated by a normal volunteer first and then applied to two clinical cases (i.e., the normal volunteer and a diabetic patient) to evaluate their respective function.
  
  
  RESULTS
  Based on the two clinical cases, by comparing the displacement fields of two selected landmarks in the normal volunteer, the proposed method showed a better performance than the original or unmodified model. Meanwhile, the comparison of the radial strain between the volunteer and patient demonstrated their apparent functional difference.
  
  
  CONCLUSIONS
  The present method could be used to estimate the LV myocardial strain and strain rate during a cardiac cycle and thus to quantify the analysis of the LV motion function.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gan
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chen
authors.forename: Shijun
authors.initials: S
authors.lastname: Zhang
authors.forename: Shenghong
authors.initials: S
authors.lastname: Ju
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Li
mesh_terms: D003920:Diabetes Mellitus / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D013314:Stress, Mechanical