Detection of murine infarcts using myocardial elastography at both high temporal and spatial resolution

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial/temporal resolution, high signal-to-noise ratio and angle-independence. In this paper, in vivo experiments were performed in anesthetized normal and infarcted mice using a high-resolution ultrasound system. Radio-frequency signals were acquired at a high frame rate (up to 8000 Hz) and used to estimate the incremental axial displacements and strains of myocardium. The incremental results were further used to calculate the cumulative displacements and strains. Two-dimensional displacement and strain images (elastograms), M-mode displacement and strain images as well as displacement and strain profiles as a function of time clearly indicated the contraction and relaxation, thickening and thinning of myocardium and demonstrated the lower motion and deformation of infarcted myocardium. The cumulative displacement and strain were less noisy than incremental images, and the cumulative strain images show the highest contrast between non-infarcted and infarcted myocardia. Finally, preliminary statistical results from nine non-infarcted mice and seven infarcted mice indicated that cumulative strain can be used to differentiate infarcted myocardium from non-infarcted myocardium. In conclusion, myocardial elastography can provide strain information at both high temporal and spatial resolution, and is capable of accurately characterizing normal myocardial function as well as detecting and localizing early myocardial infarction in vivo.