A non-invasive method for estimating regional myocardial contractility

*in vivo*would be of great value in the design and evaluation of new surgical and medical strategies to treat and/or prevent infarction-induced heart failure. As a first step towards developing such a method, an explicit finite element (FE) model-based formal optimization of regional myocardial contractility in a sheep with left ventricular (LV) aneurysm was performed using tagged magnetic resonance (MR) images and cardiac catheterization pressures. From the tagged MR images, 3-dimensional (3D) myocardial strains, LV volumes and geometry for the animal-specific 3D FE model of the LV were calculated, while the LV pressures provided physiological loading conditions. Active material parameters (*T*_{max_B}and*T*_{max_R}) in the non-infarcted myocardium adjacent to the aneurysm (borderzone) and in myocardium remote from the aneurysm were estimated by minimizing the errors between FE model-predicted and measured systolic strains and LV volumes using the successive response surface method for optimization. The significant depression in optimized*T*_{max_B}relative to*T*_{max_R}was confirmed by direct*ex vivo*force measurements from skinned fiber preparations. The optimized values of*T*_{max_B}and*T*_{max_R}were not overly sensitive to the passive material parameters specified. The computation time of less than 5 hours associated with our proposed method for estimating regional myocardial contractility*in vivo*makes it a potentially very useful clinical tool.Keywords: tagged magnetic resonance imaging, finite element modeling, numerical optimization, cardiac mechanics