Research On The Characteristics And Imaging Performance Of A Self-Made Targeted Nanobubble Ultrasound Contrast Agent

Contrast enhanced ultrasound(CEUS) can improve the contrast of ultrasound images.Currently, ultrasound contrast agents(UCA) routinely used in clinical are microbubbles.Microbubbles can not pass through the vessel wall due to their large size. Therefore, only a blood pool imaging is possible. Nanobubbles with the diameter less than 700 nm can pass through the extended tumor vessel endothelial gap, and penetrate into tumor tissue.Besides, due to angiogenesis, endothelial receptors in tumor are routinely overexpressed compared with normal tissue. Nanobubbles targeted to these endothelial receptors will actively accumulate in tumor tissue, and improve the contrast of tumor tissue imaging,which greatly promotes the diagnostic sensitivity and specificity of tumors, thus realizing the extra-vascular lesions detection and ultrasound molecular imaging.In this thesis, the basic characteristics and ultrasonic imaging performance of a self-made targeted nanobubble UCA are presented, which includes four parts: basic characterization, in-vitro contrast enhancement imaging, in-vivo contrast enhancement imaging and tumor targeting imaging, and the experiment system and the data processing method for the evaluation of targeted nanobubblees are established as well, so as to provide theoretical basis for optimizing targeted nanobubbles and promote the realization of ultrasound molecular imaging. In in-vitro ultrasonic imaging experiment, the nanobubble concentration-echo signal intensity relationship and the attenuation property of the targeted nanobubbles are investigated, showing that the echo signal intensity is greatly affected by the nanobubble concentration, but not linearly with a saturation concentration existing. In in-vivo enhancement imaging, the enhanced ultrasound images of the rat liver are observed, but the enhanced intensity and time are greatly affected by the usage dose. Tumor targeted imaging result indicates that the self-made targeted nanobubbles can effectively enhance the signal from tumor microvascular, but its tumor targeting performance still needs to be promoted.In conclusion, the self-made targeted nanobubbles have good in-vitro and in-vivo ultrasonic imaging ability, and can meet the contrast enhancement requirement of CEUS,but the nanobubble stability in ultrasound field and in-vivo and tumor targeting performance still need to be further improved.