title: Nonhomogeneous strain from sparse marker arrays for analysis of transmural myocardial mechanics.
abstract: BACKGROUND
  Knowledge of normal cardiac kinematics is important when attempting to understand the mechanisms that impair the contractile function of the heart during disease. The complex kinematics of the heart can be studied by inserting radiopaque markers in the cardiac wall and study the pumping heart with biplane cineradiography. In order to study the local strain, the bead array was developed where small radiopaque beads are inserted along three columns transmurally in the left ventricle.
  
  
  METHODS
  This paper suggests a straightforward method for strain computation, based on polynomial least-squares fitting and tailored for combined marker and bead array analyses.
  
  
  RESULTS
  This polynomial method gives small errors for a realistic bead array on an analytical test case. The method delivers an explicit expression of the Lagrangian strain tensor as a polynomial function of the coordinates of material points in the reference configuration. The method suggested in this paper is validated with analytical strains on a deforming cylinder resembling the heart, compared to a previously suggested finite element method, and applied to in vivo ovine data. The errors in the estimated strain components are shown to remain unchanged on an analytical test case when evaluating the effects of one missing bead. In conclusion, the proposed strain computation method is accurate and robust, with errors smaller or comparable to the current gold standard when applied on an analytical test case.
authors.affiliation: Division of Biomedical Modelling and Simulation, Department of Biomedical Engineering, Linköpings Universitet, SE-581 85, Linköping, Sweden. katki@imt.liu.se
authors.forename: K
authors.initials: K
authors.lastname: Kindberg
authors.forename: M
authors.initials: M
authors.lastname: Karlsson
authors.forename: N B
authors.initials: NB
authors.lastname: Ingels
authors.forename: J C
authors.initials: JC
authors.lastname: Criscione
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006321:Heart / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology*