Experimental investigation of contrast microbubble destruction

The threshold and rate of destruction of Sonazoid and Optison microbubbles insonified by 2-3 MHz imaging pulses have been investigated using a high-resolution 25 MHz active acoustic detector. Almost no microbubbles were destroyed by 2.5 MHz, 4 cycle imaging pulses with acoustic pressures less than 0.6 and 0.4 MPa for Sonazoid and Optison, respectively. Above threshold acoustic pressures the destruction rate of Sonazoid correlated well (r=0.97) with time-averaged acoustic intensity but poorly (r=0.06) with mechanical index, indicating that time-averaged acoustic intensity can be used as an index for accurately predicting the destruction rate of contrast microbubbles.