Shear wave elastography using diverging wave imaging with sliding-window coherent compounding

Shear wave elastography is a promising tool for non-invasive assessment of myocardial stiffness. As cardiac shear waves (SW) are very short-lived, their detection using ultrasound necessitates high frame rate imaging. More specifically, diverging wave imaging with coherent compounding is typically used, requiring a trade-off between time resolution and image quality. Hence, the aim of this study was to investigate if this trade-off can be circumvented for SW imaging by using a sliding-window approach during coherent compounding. In this approach, DW transmits are re-used to create a compounded frame and the number of re-used DW transmits depends on the selected overlap percentage. The proposed method was tested using phantom data and in vivo recordings. The preliminary phantom results show that frame rate can be increased using a sliding-window coherent compounding approach. However, in case of compounding 24 diverging waves, the shear wave slope in the compounded M-mode panel appeared noisier and the median value of tissue acceleration in the wave front was significantly lower (-94% without and -74% with sliding), indicating that motion information is blurred due to high number of compounded transmits. Moreover, in the in vivo recording it was observed that wave pattern and underlying motion of the heart might further blur the motion information. Hence, further optimization of the number of transmits and overlap percentage, together with advanced motion compensation should be investigated.