| BackgroundAs a non-invasive diagnosis system, ultrasound is widely applied in clinical diagnostic settings, and we have no clinical report on its teratogenecity to human being until now. Ultrasound is also widely used in therapeutic field, such as lithotripsy, tumor ablation and sonodynamic therapy. In recent years, many researchs have reported that ultrasound could not only facilitate the macromolecule and plasmid DNA delivery into cells, but also selectively and reversibly disrupt the blood-brain barrier. As a result, more and more attention had been paid to the bioeffects of ultrasound. With the advance of ultrasound application, microbubble ultrasound contrast agent (UCA), which is small enough to pass through the pulmonary circulation, was developed and applied. Since the microbubble could enhance the backscatter of blood circulation much greater than red blood cell by intravenous injection, it makes tissue perfusion imaging possible in many organs and had been accepted in clinical as an important revolutionary advance in the ultrasound field. Base on the contrast left ventricular opacification, UCA could easily delineate the endocardial border in many technically difficult patients and this helps in cardiac functional estimation, more important, contrast tissue perfusion imaging enable to evaluate myocardial ischemia, renal perfusion or the characteristical enhancement of malignancy, like hepatocellular carcinoma.The characteristic microbubble dynamics in ultrasound field was investigated with the application of UCA. The micrboubble oscillates differently in ultrasonic field with different US amplitudes. The linear oscillation with the linearity backscatter often happens under low ultrasonic intensity, and the non-linear oscillation with strong harmonic signal was generated under moderate to high intensity. Many contrast specific imaging modalities were developed for characteristic microbubble behaviors, like CPS (contrast pulse sequences) for...
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