Pseudo-Doppler Effect at a Disappearance of a Single Microbubble Translating Owing to Acoustic Radiation Force

We attempted to visualize a single microbubble driven by acoustic radiation force using a combination of pulse inversion Doppler and plane wave imaging. Commercial microbubbles, Sonazoid® underwent ultrasound exposure with a center frequency of 5.2 MHz, a pulse repetition frequency of 4 kHz, and a negative peak sound pressure of 1.59 MPa. It succeeded in separately detecting individual microbubbles with high sensitivity. The disappearance of freely-translating microbubbles could be observed as a broadened spectrum of Doppler signal, i.e. a pseudo-Doppler effect. However, the trend was not apparent in the case of wall-colliding microbubbles.