Resolving in-vivo flow fields in the systemic circulation of the mouse through combined ultrasound imaging and computational fluid dynamics

The "natural history" of aortic aneurysm formation and growth is not fully understood. Mouse models are most suitable to unravel the potential role of biomechanical factors (such as magnitude and patterns of wall shear stress), which are thought to interplay with vascular biology. The objective of this study is to explore whether high-frequency ultrasound imaging, combined with computational fluid dynamics (CFD), allows to resolve the flow field in the murine arterial vasculature. Ultrasound data were gathered in 10 male mice with a high-frequency ultrasound apparatus (Vevo 2100, Visualsonics, Toronto, Canada) equipped with a linear array probe (MS 550D, frequency 22-55 MHz). 3D digital models of the aorta were obtained from contrast-enhanced μCT images. Using the PW Doppler data as boundary conditions at inlets and outlets of these 3D models, CFD simulations yielded 3D flow fields with a temporal resolution in the order of 0.5 ms and spatial resolution determined by the computational grid density (<;<;0.1 mm). This approach, integrating imaging and CFD, provides the necessary tool for longitudinal hemodynamic studies in mice, but may also provide a modeling framework for the further optimization of high-frequency vascular ultrasound.