## 5 Conclusions  
In this work, we assessed the effect of ultrafast imaging on dispersive shear wave visualization and subsequent shear stiffness characterization by means of SWE experiments in combination with a multiphysics model of a LV phantom model with pediatric geometry. This model offers the advantage of giving access to the true biomechanical wave propagation, which is unknown in the SWE measurements. The multiphysics model of the idealized LV phantom revealed that the detected shear wave features in the time and frequency domain by ultrafast imaging do not necessarily depict the ARF-excited characteristics of the biomechanical model. Furthermore, application of the compounding technique in ultrafast imaging even altered the dispersion features in the temporal shear wave pattern for both experiments and simulations, leading to a stiffness underestimation of minimally 25% when choosing a group velocity-based algorithm instead of a phase velocity one. Additionally, the applied group speed material characterization method was very sensitive to the applied algorithm settings (such as the number of tracked data points) and the selected axial depth, as ultrafast imaging can alter the shear wave front location in the shear wave visualization. Therefore, it is important to keep a high frame rate during compounding in order to obtain an accurate representation of shear wave physics and the subsequently derived material stiffness. Future research should focus on investigating additional configurations with more advanced SWE-based material characterization to further generalize these conclusions. Nevertheless, this work presents a versatile and powerful simulation environment to evaluate the performance of ultrafast imaging in shear wave visualization and characterization with SWE, and to identify potential pitfalls in accurately capturing shear wave propagation.  
The following are available online at [[http://www.mdpi.com/2076-3417/7/8/840/s1](http://www.mdpi.com/2076-3417/7/8/840/s1)]([http://www.mdpi.com/2076-3417/7/8/840/s1](http://www.mdpi.com/2076-3417/7/8/840/s1)). Figure S1: Illustration of the effect of discarding 5 or 20 data points at the edges of each shear wave during the fitting procedure in the Time Of Flight (TOF) method: a comparison between different depths and imaging acquisitions.  
[PERSON] is the recipient of a research grant from the Flemish government agency for Innovation and Entrepreneurship (VLAIO). [PERSON] is supported by the Research Foundation Flanders (FWO). This research was also supported by a grant for international mobility from the CWO (committee for scientific research at the Faculty of Engineering and Architecture at Ghent University) to facilitate the research visits at the Institut Langevin (Paris, France).  
[PERSON], [PERSON], [PERSON] and [PERSON] conceived and designed the experiments/simulations; [PERSON] and [PERSON] performed the experiments under supervision of [PERSON]; [PERSON] analyzed the experimental data; [PERSON] performed the finite element simulations; [PERSON] performed ultrasound simulations with help from [PERSON] and [PERSON]; [PERSON] is the main author of the paper; critical revision were provided by all co-authors.  
The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.