"Stable" inertial cavitation

This note compares theoretical predictions of pressure waves scattered by free gas bubbles with recent acoustical determinations of cavitation thresholds for individual microbubbles of the surfactant-stabilized contrast agent Sonazoid(R). The results indicate that surfactant-coated microbubbles undergo "stable" (i.e., repetitive) inertial cavitation above a threshold of 0.3 to 0.4 MPa at 2.5 MHz, and that irreversible postcollapse bubble fragmentation usually requires much higher pressures (approximately 1.5 MPa). Adverse bioeffects can be expected in vivo far below these fragmentation pressures when contrast agents are present. With diagnostically relevant exposures, the threshold for the generation of petechiae in skeletal muscle is approximately 0.6 MPa at 2.5 MHz.