Measurement and correlation of acoustic cavitation with cellular bioeffects.

Using broadband noise as a measure of cavitation activity, this study determined the kinetics of cavitation during sonication of Optison contrast agent and tested whether cellular bioeffects can be predicted by cavitation dose. Cell suspensions were exposed to ultrasound at varying acoustic frequency, pressure, exposure time, Optison concentration and cell type to obtain a broad range of bioeffects, i.e., intracellular uptake and loss of viability, as quantified by flow cytometry. We found that cavitation activity measured by broadband noise increased and peaked within 20 ms and then decayed with a half-life of tens to hundreds of milliseconds. Intracellular uptake and loss of viability correlated well with the cavitation dose determined by the time integral of broadband noise magnitude. These results demonstrate that broadband noise correlates with bioeffects over a broad range of experimental conditions, which suggests a noninvasive feedback method to control ultrasound's bioeffects in real time.