Ultrasound catheter for microbubble based drug delivery

An intravascular ultrasound (IVUS) catheter was designed to guide and locally deliver microbubbles carrying therapeutic agents. Optimal insonation parameters were determined by modeling microbubble translational displacements using the coupled 1D Rayleigh-Plesset and Drag-displacement equations. A transducer assembly was designed based on the results of microbubble simulations and a Finite Element Analysis (FEA) Model. The transducer components were fabricated then assembled into a 1.4 mm (OD) catheter tube. Hydrophone tests were performed to measure transducer output and the resulting output was compared to the FEA model. The final catheter was tested for gene delivery effectiveness by transfecting cells with a cytomegalovirus-plasmid kinase (CMV-PK) Red plasmid DNA. Wall-less flow phantom experiments were also performed to demonstrate the effectiveness of translating microbubbles across a vessel using ultrasound radiation force by measuring change in image intensity of a B-mode scan of the vessel. The resulting change in image intensity was approximately 15 dB. A follow-up experiment with the wall-less flow phantom was performed where microbubbles were initially translated and then burst, resulting in an intensity change of up to 12 dB and then a decrease after destruction back down to 0 dB.