Ultrasound-enhanced delivery of therapeutic-loaded echogenic liposomes is under development for vascular applications using the EkoSonic Endovascular System. In this study, fibrin-targeted echogenic liposomes loaded with an anti-inflammatory agent were characterized before and after infusion through an EkoSonic catheter. Cavitation activity was nucleated by Definity or fibrin-targeted, drug-loaded echogenic liposomes infused and insonified with EkoSonic catheters. Passive cavitation imaging was used to quantify and map bubble activity in a flow phantom mimicking porcine arterial flow. Cavitation was sustained during 3-min infusions of Definity or echogenic liposomes along the distal 6 cm treatment zone of the catheter. Though the EkoSonic catheter was not designed specifically for cavitation nucleation, infusion of drug-loaded echogenic liposomes can be employed to trigger and sustain bubble activity for enhanced intravascular drug delivery.
The objective of this study was to explore the location and amount of cavitation nucleation from Definity® or drug-loaded echogenic liposomes infused through the EkoSonic endovascular system (Boston Scientific, Arden Hills, MN) in an in vitro model mimicking porcine femoral arterial flow. Passive cavitation images were acquired during echocontrast agent infusion and 2.2 MHz EkoSonic ultrasound exposure over a range of ultrasound drive powers (4 W-47 W), and the ultraharmonic and inharmonic energy patterns were compared.
For image guidance of ultrasound-mediated drug delivery using Definity® infusions through the Ekosonic Endovascular System (Boston Scientific, Arden Hills, MN), composite cavitation images were formed using ultraharmonic and inharmonic energy values in the green and red channels, respectively, and overlayed on B-mode images. The extension of the traditional 1D color bar to a 2D color map enabled simultaneous display of ultraharmonic and inharmonic energy, coupled with B-mode imaging for spatial localization.
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