Effect of pressure in blood vessel model on ultrasound scattered power from microbubbles

To obtain a clearer ultrasonic diagnostic image using a microbubble contrast agent, investigation of power scattering from microbubbles is indispensable. The scattered power from the microbubbles should be as large as possible, and, since it depends largely on the elasticity of the microbubble shells, it is desirable to have as large an elasticity as possible. However, microbubbles with weak shells are easily broken under high pressure. Although hard-shell microbubbles are effective under high pressure, these microbubbles do not consistently produce scattered power. Thus, it is very important to fabricate microbubbles that can be used as ultrasound contrast agents. In this study, the effect of pressure on the scattered power and longevity of microbubbles in a blood vessel model was investigated using a blood vessel model system. Microbubbles coated with sodium laurate were compared with hollow silicone microcapsules (Grandoll) which have a different shell type. The effect of the pressure in the blood vessel model on these microbubbles was investigated by ultrasound scattered power measurement. According to the results, the scattered power from the sodium laurate microbubbles decreases when the pressure increases because of the disappearance of microbubbles. In contrast, the effect of pressure on scattered power from hard-shell microbubbles is negligible.