Numerical Simulation of Ultrasonic Color Blood Flow Imaging in the Carotid Artery: Comparing a 1^st Order and Fully Coupled Approach

Ultrasonic imaging is widely applied for visualization of blood flow using different imaging modalities. However, due to the inherent physical limitations of the ultrasonic imaging process, the actual flow dynamics and the information embedded in the ultrasound image do not necessarily strictly correspond. Computational fluid dynamics (CFD) can play an important role in interpreting and improving ultrasound imaging via numerical simulation of ultrasound images. For this purpose, CFD velocity data can be directly processed to mimic ultrasonic images (1^st order approach) or can be further coupled to ultrasound simulation software, providing a fully coupled approach. We compared both methods for the clinically relevant case of color flow imaging of the carotid artery. We conclude that for this application, the 1st order approach leads to results lacking indispensable properties of the imaging process, i.e., (i) the imaging dynamics, and (ii) the statistical properties of the ultrasonic velocity estimator.