C5: Biomedical Imaging II

TWO-DIMENSIONAL ULTRASONICMEASUREMENT-INTEGRATED SIMULATION OF BLOOD FLOW IN A CAROTID ARTERY CONSIDERING DEFORMATION OF THE BLOOD VESSEL

Daisuke Harada1, Toshiyuki Hayase2, Suguru Miyauchi2, Kosuke Inoue2,

1Tohoku Gakuin University, Japan
2Institute of Fluid Science, Tohoku University, Japan

Atherosclerosis is related to circulatory diseases and has a close relationship with hemodynamics. Therefore, hemodynamic information is crucial for elucidation of the mechanism and the development of a new diagnostic method for circulatory diseases. As a method to acquire hemodynamic information, Funamoto et al. proposed ultrasonic-measurementintegrated (UMI) simulation, showing its advantages over conventional numerical simulations. Aiming at clinical application, a two-dimensional UMI (2D-UMI) blood flow analysis system was developed. The system has functions necessary for automatic blood flow analysis of a carotid artery, which is a common site of atherosclerosis based on standard clinical ultrasonic measurement, such as extraction of the blood vessel configuration and inflow velocity estimation. The versatility of this system was shown for clinical measurement data. In this 2D-UMI blood flow analysis system, however, the blood vessel shape extracted from the ultrasonic measurement is a time-averaged shape and the deformation of the blood vessel synchronizing with the heartbeat is not considered. The rectangular grids used in the analysis also make it difficult to represent the curvature of the blood vessel shape and to evaluate the wall shear stress accurately. The purpose of the present study, therefore, was to establish a method of 2D-UMI blood flow simulation in a carotid artery with accurate consideration of the blood vessel motion and shape. For extraction of time-dependent blood vessel shape, a pattern matching technique was applied to sequential B mode images. A boundaryfitted grid was employed for accurate representation of the blood vessel shape and wall shear stress. The effectiveness of the proposed method was examined by experiment. The blood flow in a carotid artery of a healthy volunteer was analyzed by this new method and the existing one. The results of the both methods were compared with that of the ultrasonic measurement, showing the superiority of this new method.

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