Effect of Feedback Conditions on Blood Viscosity Estimation Method in Two-Dimensional Ultrasonic-Measurement-Integrated Blood Flow Analysis

Wall shear stress from blood flow is particularly considered to be a factor that promotes atherosclerosis, and is expressed as the product of blood viscosity and velocity gradient of blood flow. If in vivo wall shear stress can be evaluated by simultaneously measuring blood flow velocity and blood flow velocity gradient in real time, it is thought that blood viscosity estimation leads to elucidation of mechanism of arteriosclerosis and early detection. In previous study, a blood viscosity estimation method was proposed by applying two-dimensional ultrasonic-measurement-integrated (2D-UMI) blood-flow analysis reproducing an intravascular blood flow field by feeding back an ultrasonic measurement to a numerical fluid analysis. The estimation accuracy was examined by a numerical experiment under specific conditions. However, the effects of analysis conditions on this method are not verified. Accordingly, we investigated the effects of the feedback domain and the feedback gain on the estimation accuracy, and examined appropriate feedback conditions by a numerical experiment for a blood flow field of a straight blood vessel assuming a common carotid artery. As a result, it was suggested that the estimation accuracy generally improves as the feedback gain is increased in a specific feedback domain.