Multiphysics modeling in support of ultrasonic image development: Integration of fluid-structure interaction simulations and Field II applied to the carotid artery

Previously, we proposed a multiphysics model coupling computational fluid dynamics (CFD) and Field II, allowing assessment of the performance of current and new blood flow estimators (e.g. color flow imaging=CFI, PW Doppler, speckle tracking, vector Doppler) in the carotid artery against ground truth information retrieved from CFD. Important limitations however were the rigid walls and the absence of the arterial wall and surrounding tissue in the simulations. The aim of this study was to improve and expand the model to a more realistic setup of a distensible carotid artery embedded in surrounding tissue. For this purpose, we integrated fluid-structure interaction (FSI) simulations with an ultrasound simulator (Field II), which allows comparison of the ultrasound (US) images with the input data from FSI. Field II represents tissue as random points on which ultrasound waves reflect and whose position can be updated based on the flow field and vessel wall deformation from FSI.We simulated the RF-signal of a patient-specific carotid bifurcation, including the blood pool as well as the vessel wall and surrounding tissue. Realism of the multiphysics model was demonstrated with duplex images.