Quantitative imaging of myocardium elasticity using supersonic shear imaging

The concept of shear wave elastography is applied to the heart. The goal of this study is to demonstrate the potential of this technique for quantifying the elasticity time variation of the myocardium. Experiments are performed in vivo on N=10 sheep with a linear high frequency probe placed directly on the myocardium. The feasibility of generating and imaging the propagation of shear wave in the beating heart and estimating locally the myocardium elasticity at each stage of a single heart cycle is investigated by repeating acquisition of shear wave propagation between 10 and 20 times per second. The dependence of estimated shear modulus with probe angle (short axis to long axis), depth and left ventricle pressure is studied in vivo and ex vivo. The short term effect of a local ischemia is also studied by coronary arteries ligature, showing the sensitivity of the technique to a local loss of contractility in the myocardium. Finally, this study shows the potential of shear wave elastography as a quantification tool of myocardium mechanical properties.