On the Robustness of Multi-Pulse Techniques Against Undesired Effects in Contrast Enhanced Ultrasound Imaging

One of the most important issues in the field of contrast agents-based echographic imaging is the development of techniques able to separate the echoes of such contrast media from the echoes of the biological tissue: in particular in literature could be found various solutions concerning the use of multiple transmitted signals and the combination of related echoes. These techniques may undergo a reduction of performance, due to some undesired effects normally not taken into account, such as non-linearities introduced by hardware equipment and tissue propagation, thermal and electronic noise and body motion between successive pulses. Here we introduce a simulation tool that we developed, able to calculate the backscattered echo from a contrast agents population immersed in biological tissue, considering all the previous effects. By means of this tool, we performed a comparative analysis of the various multi-pulse techniques on the basis of the contrast to tissue ratio (CTR) and the signal to noise ratio (SNR) before and after the echoes summation. The results show the potentially strong impact of the undesired effects on these techniques and may provide useful hints on the choice of the particular technique to be applied, regarding the specific diagnostic application addressed and the hardware characteristics.