Acoustic method for real-time visualization of microbubble movements and rupture

The behavior of microbubbles during insonation is typically observed through optical methods based on the use of high frame-rate cameras. In this paper, a new approach is described, in which a high-speed processing board is coupled to a standard ultrasound TX-RX to interrogate small concentrations of microbubbles suspended in water. The acquired data is presented simultaneously on two displays. In a classical M-mode display, distinct traces indicate the amplitude and position of individual bubble-echoes over time. In the multigate Doppler display, the instantaneous velocities of all bubbles intercepted by the US beam are shown. Tests performed in different experimental conditions clearly show how individual microbubbles are pushed away from the transducer depending on the transducer excitation and pressure distribution along the beam axis. Bubble rupture is also clearly shown in both display modes. The new approach thus demonstrates a promising means for the investigation of microbubble behavior in ultrasound fields.