Contrast-enhanced flow imaging with phase-coded pulse sequences

The measurement of blood flow velocities is a challenging task. The effect of nonlinear scattering from microbubbles is commonly used for contrast specific imaging. Linear scattering from microbubbles is not contrast specific, yet it contributes more to the echo signal. To optimize flow imaging with contrast agents, it is desirable to exploit linear scattering and nonlinear scattering to improve sensitivity without sacrificing specificity. This can be achieved by incorporating the amplitude and phase dependencies of the fundamental and harmonic spectral components in the Doppler processing. The separability of the aforementioned components is achieved by phase-coding (or amplitude-coding) of the transmit pulses.