Development and feasibility study of a two-dimensional ultrasonic-measurement-integrated blood flow analysis system for hemodynamics in carotid arteries

Abstract

Prevention and early detection of atherosclerosis are critical for protection against subsequent circulatory disease. In this study, an automated two-dimensional ultrasonic-measurement-integrated (2D-UMI) blood flow analysis system for clinical diagnosis was developed, and the feasibility of the system for hemodynamic analysis in a carotid artery was revealed. The system automatically generated a 2D computational domain based on ultrasound color Doppler imaging and performed a UMI simulation of blood flow field to visualize hemodynamics in the domain. In the UMI simulation, compensation of errors was applied by adding feedback signals proportional to the differences between Doppler velocities by measurement and computation while automatically estimating the cross-sectional average inflow velocity. The necessity of adjustment of the feedback gain was examined by analyzing blood flow in five carotid arteries: three healthy, one sclerosed, and one stenosed. The same feedback gain was generally applicable for the 2D-UMI simulation in all carotid arteries, depending on target variables. Thus, the present system was shown to be versatile in the sense that the parameter is patient independent. Moreover, the possibility of a new diagnostic method based on the hemodynamic information obtained by the 2D-UMI simulation, such as a waveform of the cross-sectional average inflow velocity and wall shear stress distributions, was suggested.

Study of Estimation Method for Unsteady Inflow Velocity in Two-Dimensional Ultrasonic-Measurement-Integrated Blood Flow Simulation

“…A prototype of the 2D-UMI blood flow analysis system for a human carotid artery [7] (Fig. 1) is herein explained.…”

“…Doppler velocity is the component of the blood flow velocity vector projected in the direction of the ultrasonic beam. In a previous study, a numerical experiment of three-dimensional blood flow analysis by UMI simulation [6] and development of a two-dimensional UMI (2D-UMI) blood flow analysis system for clinical application [7] were performed (Fig. 1).…”

A Review of Measurement-Integrated Simulation of Complex Real Flows

“…In this section, applications of MI simulation are presented ranging from fundamental turbulent flow in pipes [1] [13] [23] and Karman vortices in a wind tunnel [14] [24] to clinical application of diagnosis of blood flows in the human body [16] [25]- [27].…”

“…Recently, Kato et al [27] have developed an automated two-dimensional UMI (2D-UMI) blood flow analysis system for clinical diagnosis, and have investigated the feasibility of the system for hemodynamic analysis in a carotid artery. The system automatically generates a 2D computational domain based on ultrasound color Doppler imaging and performs a 2D-UMI simulation of blood flow field to visualize hemodynamics in the domain.…”

“…In Section 2, formulations of MI simulation are presented, including governing equations of an observer for a flow field, those of a linearized error dynamics describing the convergence of the observer [21], and stabilization of the numerical scheme, which is important in implementation of MI simulation [22]. Applications of MI simulation presented in Section 3 range from fundamental turbulent pipe flows [1] [13] [23] and Karman vortices in a wind tunnel [14] [24] to clinical application to diagnosis of blood flows in a human body [16] [25]- [27].…”