THE EFFECT OF ULTRASOUND FRAME RATE ON PERFLUOROCARBON-EXPOSED SONICATED DEXTROSE ALBUMIN MICROBUBBLE SIZE AND CONCENTRATION WHEN INSONIFYING AT DIFFERENT FLOW-RATES, TRANSDUCER FREQUENCIES, AND ACOUSTIC OUTPUTS

The purpose of this article was to compare the effects of 1 and 30 Hz frame rates on perfluorocarbon-exposed sonicated dextrose albumin micr obubble size and concentration in a flow cell containing either saline or blood at 37 degrees C. Microbubble size and concentration of perfl uorocarbon-exposed sonicated dextrose albumin were measured after inso nation at different acoustic outputs, transducer frequencies, and flow rates with the use of the two different frame rates and compared with no ultrasound exposure. At 2.0 MHz insonation frequency, microbubble concentration was significantly reduced with the use of a 30 Hz frame rate and peak negative pressures of 1.1 megaPascal (mPa). This destruc tion did not occur when using a lower acoustic output, a 1 Hz frame ra te, or when flow rate was increased to 100 cc/min. One-hertz frame rat es at 2.0 MHz resulted in a significantly larger mean microbubble size than 30 Hz or no ultrasound in both saline and blood, which was in pa rt due to selective destruction of smaller microbubbles. These finding s indicate that 30 Hx frame rates destroy perfluorocarbon-exposed soni cated dextrose albumin microbubbles only at higher diagnostic acoustic outputs. A 1 Hz frame rate prevents this destruction, especially dest ruction of larger (>5.0 mu m) microbubbles.