2D myocardial strain in the mouse through spatial compounding: In-vivo feasibility study

Ultrasound assessment of myocardial strain can give valuable information on regional cardiac function. Speckle tracking is often used for this purpose as it can estimate the 2D myocardial strain tensor. However, in the mouse setting, speckle tracking remains challenging due to the high heart rate and the relatively thin wall compared to the typical size of the speckles. We have previously shown using simulated data sets that spatial compounding of axial velocities obtained at 3 steering angles can outperform 2D speckle tracking for 2D strain estimation in the mouse heart. In this study, beam steering was applied at -20°, 0° and 20° on short axis views of 5 control and 6 infarct mice. The lateral motion component was reconstructed through spatial compounding and results were compared to tagged μMRI. Circumferential estimates quantified by means of ultrasound and MRI could both detect regional dysfunction. Between echo and MRI, a good regression coefficient was obtained for circumferential strain estimates (r = 0.69), while radial strain estimates correlated only moderately (r = 0.37).