A novel 2D speckle tracking method for high frame rate echocardiography

Speckle tracking echocardiography (STE) is a clinical tool to non-invasively assess regional myocardial function through the quantification of regional motion and deformation. Even if the time resolution of STE can be improved by high frame rate (HFR) imaging, dedicated HFR STE algorithms have to be developed to detect very small inter-frame motions. Therefore, in this paper, we propose a novel 2D STE method, purposely developed for HFR echocardiography. The 2D motion estimator consists of a 2-step algorithm based on 1D cross-correlations to separately estimate the axial and lateral displacement. The method was first optimized and validated on simulated data giving an accuracy of ~3.3% and ~10.5% for the axial and lateral estimates, respectively. Then, it was preliminary tested in-vivo on 10 healthy volunteers showing its clinical applicability and feasibility. Moreover, the extracted clinical markers were in the same range as those reported in literature. Also, the estimated peak global longitudinal strain was compared with that measured with a clinical scanner showing good correlation and negligible differences (-20.94% vs -20.31%, p-value = 0.44). In conclusion, a novel algorithm for STE was developed: the RF signals were preferred for the axial motion estimation, while envelope data for lateral motion. Furthermore, using 2D kernels, even for 1D cross-correlation, makes the method less sensitive to noise.