In this study, we investigated the permeability variation of blood vessels produced by focused ultrasound in presence of micro-bubbles (MB). Both diameter and radius of curvature for the ultrasound transducer are 1.6 cm, and the driving frequency of the transducer is 1.0 MHz. The parameters of ultrasound sonication are pulse length 10 ms, duty cycle 1%, sonication duration 60s, and peak negative pressure 0.6 MPa. The ultrasound contrast agent (UCA), SonoVue, was used as the MB to enhance the microvessels permeability. We used rhodamine-labeled dextrans as macromolecular drug carrier, and observed their transport in vivo by two-photon fluorescence microscopy (TPM). The results of this study display that focused ultrasound with MB can disrupt the blood vessel walls for the normal tissue and cause the extravasation of macromolecules and the whole process can be observed from the real-time TPM image.
