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Multi-Modality Imaging Enables Detailed Hemodynamic Simulations in Dissecting Aneurysms in Mice

E. Phillips, P. Di Achille, M. Bersi, J.. Humphrey, C. Goergen
IEEE Trans Med Imaging, vol. 36, issue 6, June 2017

A multi-modality imaging based modeling approach was used to study complex unsteady hemodynamics and lesion growth in a dissecting abdominal aortic aneurysm model. We combined in vivo ultrasound (top panel) and in vitro optical coherence tomography to obtain the high resolution needed to construct detailed hemodynamic simulations over large portions of the murine vasculature (bottom panel). The ultrasound data is from a high temporal resolution scan over a representative cardiac cycle, revealing high velocity flow and the presence of an intramural thrombus. The simulation is color-coded to display the magnitude of blood flow velocity with high velocity (red) anterograde flow and low velocity (blue) recirculating flow. We illustrate this approach for a spectrum of dissecting abdominal aortic aneurysms induced in male apolipoprotein E-null mice by high-dose angiotensin II infusion. In vivo morphological and hemodynamic data provide information on volumetric lesion growth and changes in blood flow dynamics, respectively, occurring from initial aortic dissection. We validated the associated computational models by comparing results on time-varying outlet flows and vortical structures within the lesions. The lesion shown in the graphical abstract exhibited abrupt expansion and formation of thrombus. Other mice developed similar abdominal aortic aneurysms, but with different expansion rates and thrombus patterns. We attribute the differences in final size and composition of these lesions to the different computed flow and vortical structures we obtained in our mouse-specific fluid dynamic models. Our imaging-based computational findings suggest a link between perturbations in hemodynamic metrics and aneurysmal disease heterogeneity.