title: Toward ultrasound molecular imaging with phase-change contrast agents: an in vitro proof of principle.
abstract: 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.
authors: Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors: Paul S
authors: PS
authors: Sheeran
authors: Jason E
authors: JE
authors: Streeter
authors: Lee B
authors: LB
authors: Mullin
authors: Terry O
authors: TO
authors: Matsunaga
authors: Paul A
authors: PA
authors: Dayton
mesh_terms: D002478:Cells, Cultured; D003287:Contrast Media / Q000032:analysis* / Q000138:chemical synthesis*; D042783:Endothelial Cells / Q000000981:diagnostic imaging*; D005260:Female; D005466:Fluorocarbons / Q000138:chemical synthesis; D006801:Humans; D057054:Molecular Imaging / Q000379:methods*; D010865:Pilot Projects; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons