Contrast-Enhanced Photoacoustic Imaging of Low-boiling-point Phase-Change Nanodroplets

Contrast-enhanced photoacoustic imaging has shown a great potential in various medical imaging applications. Although different types of customized contrast agents were developed over the decade, there is no commercial FDA-approved photoacoustic imaging contrast agents. This study shows the in vivo photoacoustic imaging of low-boiling-point phase-change nanodroplets, made using ingredients from an existing commercial microbubble ultrasound contrast agents without any dye coated, in a mouse to demonstrate that commercial ultrasound contrast agents may have the potential to be used to facilitate the clinical translation of photoacoustic imaging. Decafluorobutane-core lipid-shell nanodroplets were manufactured. The homemade decafluorobutane droplet solution has the same core composition as the commercial MicroMarker© (FUJIFILM, Visualsonics) and Sonazoid© (GE Healthcare) contrast microbubbles. The results show that, after activation, signals from the spleen region have been significantly enhanced. As the droplets do not have any dye coating on the surface, one potential reason for the photo-activation of the droplets could be that the blood cells nearby absorb energy from the light. As the ingredients of the droplets are the same as some existing commercial microbubble contrast agents, this study demonstrates that droplets made from condensed commercial bubbles may have the potential to be used to facilitate the clinical translation of contrast-enhanced photoacoustic imaging.