P5B-13 Improved Ultrasound Contrast Agent Detection in a Clinical Setting

Optical studies have shown threshold behaviour of phospholipid-coated contrast agent microbubbles. Below the acoustic pressure threshold, phospholipid-coated microbubbles oscillate significantly less than above the threshold. For microbubbles smaller than 3.0 mum diameter, pressure-dependent scattering was measured, which is believed to be the result of threshold behaviour. The aim of this study is to investigate if threshold behaviour is useful to enhance the contrast in power modulation images. For levovist and BR14 suspensions (filtered and native), a programmable ultrasound system recorded power modulation images at 2 MHz and acoustic pressures between 25 and 250 kPa. Results were compared to intensities recorded with a commercial ultrasound system. An inverse relationship between the pressure-dependency of the scattering and microbubble size was observed. Threshold behaviour enhances the contrast in power modulation images. Using a suspension with microbubbles smaller than 2.0 mum, at 2 MHz transmit frequency and an acoustic pressure of 250 kPa, the CTR value was 33 dB, which is 13 dB higher compared to a native BR14 suspension.