Comparison Between Passive and Reverberant Shear Wave elastography: Preliminary results

Shear Wave Elastography (SWE) involves a set of non-invasive approaches focused on providing quantitative information about tissue stiffness. Current approaches rely on the coherent tracking of shear wave propagation along a single direction to estimate the Shear Wave Speed (SWS). However, in some cases, is not possible to fulfill this assumption. To overcome this, different alternatives based on the calculation of the SWS from a complex elastic wave field have been proposed. Passive Shear Wave Elastography (PSWE) and Reverberant Shear Wave Elastography (RSWE) are both techniques that have been independently tested on phantoms and in vivo applications; however, a thorough comparison between them has not been reported. In this work, PSWE and RSWE were compared in a two-layer tissue-mimicking phantom. Two experiments were realized to evaluate the performance of both approaches by using a Verasonics Ultrasound System for data acquisition and different mechanical sources for reverberant field generation. The results show that PSWE and RSWE can provide qualitative and quantitative contrast differentiation in the SWS map reconstruction. PSWE generally provided lower CV and higher SNR in hard layers compared to RSWE, while RSWE excelled in softer materials, particularly in SWS consistency and CR values. These findings suggest that PSWE may be more suitable for harder materials, whereas RSWE could be preferred for softer tissues. The differential effectiveness highlighted in this study has significant implications for optimizing elastography usage in clinical diagnostics and material testing, potentially guiding tailored applications based on material properties.