Diagnostic ultrasound and contrast microbubbles on new capillaries

Objective To observe the effects of diagnostic ultrasound and contrast microbubbles on the new capillaries of hepatic VX2 tumors in rabbits. Methods Tumor growth rates of six rabbits were observed by B-mode sonography. When the tumors reached 0.6 cm to 1.0 cm in diameter, all the rabbits were used in research. The rabbits were divided into two groups-treatment group and control group. The rabbits in treatment group were injected with contrast microbubbles, while the rabbits in control group were injected with the same dose of physiological salt solution. First we found the place of the tumor by ultrasound imaging, then contrast microbubbles (Optison) at the dose of 0.10 ml/kg were injected into the vascular system of rabbits through the ear veins. At the same time, the tumors were observed by B-mode sonography at a mechanical index (MI) of 1.4. The whole process of imaging lasted about six to seven minutes. After that, the tumors were quickly cut off for electronic microscope and light micrscope (HE stain) observations. Results Contrast microbubbles can significantly enhance tumors sonography, and they also have bioeffects on the new capillayies of tumors. There were no significantly changes in light microscope images, but signicantly ultrastructure changes in the endocells of the capillaries were found in electronic microscope images, such as: swellen mitochondria, myelin figure, and cavilizition of cytoplasm etc. Conclusion Diagnostic ultrasound at high mechanical index plus contrast microbubbles can cause capillaries' ultrastructure changes in tumors.