P4A-4 Evaluation of Cardiac Dyssynchrony Using Strain Imaging

Strain and strain rate imaging provide new information for evaluation of regional myocardial function. Clinical diagnosis using echocardiography is based on visually assessed wall motion scoring, which is semi quantitative and heavily weighted on operator experience and expertise. Cardiac motion estimation methods such as Tissue Doppler and elastography can be used to assess myocardial muscle displacements, providing quantitative parameters such as the strain-rate and strain. In this paper we evaluate the ability of strain imaging to provide localized displacement and strain information over a small region of interest over the entire cardiac cycle. In addition, ultrasound frame rate requirements for accurate estimation of tissue displacements and strain in an object undergoing cyclic compressions at rates that mimic the contractions of the heart is evaluated. Sinusoidal compressions were applied to a uniformly elastic phantom. Local displacements and strains in the phantom material are estimated using a newly developed two-step, two-dimensional cross-correlation method. Our results indicate that accurate evaluation of displacements and strain require frame rate greater than ten times the compression frequency. In-vivo results derived from short-axis views of the heart acquired from normal human volunteers also demonstrate this frame rate requirement for elastography.