Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
Ultrasound Med Biol. 2013 May;39(5):893-902. doi: 10.1016/j.ultrasmedbio.2012.11.017. Epub 2013 Feb 27.
Phase-change contrast agents (PCCAs), which normally consist of nanoscale or microscale droplets of liquid perfluorocarbons in an encapsulating shell, can be triggered to undergo a phase transition to the highly echogenic gaseous state upon the input of sufficient acoustic energy. As a result of the subsequent volumetric expansion, a number of unique applications have emerged that are not possible with traditional ultrasound microbubble contrast agents. Although many studies have explored the therapeutic aspects of the PCCA platform, few have examined the potential of PCCAs for molecular imaging purposes. In this study, we demonstrate a PCCA-based platform for molecular imaging using α(v)β(3)-targeted nanoscale PCCAs composed of low-boiling-point perfluorocarbons. In vitro, nanoscale PCCAs adhered to target cells, could be activated and imaged with a clinical ultrasound system and produced a six-fold increase in image contrast compared with non-targeted control PCCAs and a greater than fifty-fold increase over baseline. Data suggest that low-boiling-point nanoscale PCCAs could enable future ultrasound-based molecular imaging techniques in both the vascular and extravascular spaces.
相变型对比剂（PCCAs）通常由纳米级或微级别的液态全氟碳化合物液滴在包封壳中组成，在输入足够的声能后，可以触发其发生从高度声敏的液态向气态的相转变。由于随后的体积膨胀，出现了许多传统超声微泡对比剂无法实现的独特应用。尽管许多研究已经探讨了 PCCA 平台的治疗方面，但很少有研究探讨 PCCA 用于分子成像的潜力。在这项研究中，我们展示了一种基于 PCCA 的平台，该平台使用由低沸点全氟碳化合物组成的靶向 α(v)β(3)的纳米级 PCCA 进行分子成像。在体外，纳米级 PCCA 附着于靶细胞，可用临床超声系统激活和成像，与非靶向对照 PCCA 相比，图像对比度增加了六倍，与基线相比，增加了五十多倍。数据表明，低沸点纳米级 PCCA 可使未来的血管内和血管外超声分子成像技术成为可能。
