"Stable" inertial cavitation

This note compares theoretical predictions of pressure waves scattered by f ree gas bubbles with recent acoustical determinations of cavitation thresho lds for individual microbubbles of the surfactant-stabilized contrast agent Sonazoid (R). The results indicate that surfactant-coated microbubbles und ergo "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 fragmen tation usually requires much higher pressures (similar to1.5 MPa). Adverse bioeffects can be expected in vivo far below these fragmentation pressures when contrast agents are present. With diagnostically relevant exposures, t he threshold for the generation of petechiae in skeletal muscle is similar to0.6 MPa at 2.5 MHz. (C) 2001 World Federation for Ultrasound in Medicine & Biology.