1J-1 Blood Flow Velocity Vector Imaging with High Frame Rate Imaging Methods

Conventional blood flow imaging is an important medical diagnostic tool. In this paper, the same processing technique is applied to the high frame rate (HFR) imaging method developed previously to obtain two-dimensional (2D) (in principle, the method is also applicable to three-dimensional (3D)) blood flow velocity vector images. This takes advantage of the HFR imaging method where multiple 2D or 3D images, instead of a single line, can be reconstructed from a single transmission with multiple reception beams steered at different angles. To show the feasibility of the method, an in vivo experiment of an artery of the right arm of a volunteer was performed with a home-made HFR imaging system. In the experiment, a broadband linear array transducer of 128 elements, 5-MHz center frequency, 38.4-mm aperture, 5-mm elevation width, and 20-mm elevation focal distance was used. The transducer was excited with a one-cycle sine wave centered at the frequency of the transducer to produce pulsed plane waves at a repetition period of 80 microseconds. Echo signals were digitized at 40-MHz and 12-bit resolution. A set of two 2D radio-frequency (RF) (before the envelope detection) images steered at 0 (perpendicular to the transducer surface) and 15 degrees in reception, respectively, was reconstructed from each transmission. Blood flow velocity component images were reconstructed simultaneously from these images with the conventional color flow processing techniques using 16 transmissions. Combining the velocity component images, velocity vector images at a frame rate of 12,000 frames/s can be obtained