2H-3 Imaging of Murine Infarcts Using Myocardial Elastography at Both High Temporal and Spatial Resolution

Abstract

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution, and high precision. In this paper, in vivo experiments were performed in anesthetized normal and infarcted mice (one day post-LAD ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770 VisualSonics Inc.). Radio-frequency (RF) signals of the left ventricle (LV) in long-axis view and the associated electrocardiogram (ECG) were simultaneously acquired. Using the retrospective ECG gating technique, an extremely high frame rate (up to 8 kHz) was achieved that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Results clearly depicted the contraction, relaxation, thickening and thinning of LV in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole, rather than thickening as in the normal case. Preliminary statistical results from nine normal mice and seven infarcted mice indicated the capability of the cumulative strain in differentiating infarcted from normal myocardium. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (0.125 ms) and spatial (50 mum) resolution, as well as high precision (minimum displacement 0.05 mum). Myocardial elastography was capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle at that resolution and detecting and localizing myocardial infarction in vivo