Developments of angle-independent velocity estimator for blood flow imaging

Abstract The frame rate in ultrasonography is significantly better than those in other medical imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), even under a traditional imaging scheme, i.e., line-by-line scanning with a focused transmit beam. However, a higher frame rate would provide more possibilities in measurements of rapidly altering phenomena, such as cardiovascular dynamics. High-frame-rate imaging with unfocused transmit beams, such as plane and diverging transmit beams, enables an extremely high frame rate of over several thousand frames per second and has shown to be effective for cardiovascular applications including blood flow imaging. Although an extremely high temporal resolution is achieved by the high-frame-rate ultrasound imaging, conventional methods for blood flow imaging suffer from a limitation, i.e., a velocity component only in the direction of ultrasonic propagation is measured. In this article, recent developments in angle-independent blood flow imaging with high-frame-rate ultrasound are discussed.