Ultrasonic technologies in imaging and drug delivery

Abstract

Ultrasonic technologies show great promise for diagnostic imaging and drug delivery in theranostic applications. The development of functional and molecular ultrasound imaging is based on the technical breakthrough of high frame-rate ultrasound. The evolution of shear wave elastography, high-frequency ultrasound imaging, ultrasound contrast imaging, and super-resolution blood flow imaging are described in this review. Recently, the therapeutic potential of the interaction of ultrasound with microbubble cavitation or droplet vaporization has become recognized. Microbubbles and phase-change droplets not only provide effective contrast media, but also show great therapeutic potential. Interaction with ultrasound induces unique and distinguishable biophysical features in microbubbles and droplets that promote drug loading and delivery. In particular, this approach demonstrates potential for central nervous system applications. Here, we systemically review the technological developments of theranostic ultrasound including novel ultrasound imaging techniques, the synergetic use of ultrasound with microbubbles and droplets, and microbubble/droplet drug-loading strategies for anticancer applications and disease modulation. These advancements have transformed ultrasound from a purely diagnostic utility into a promising theranostic tool.

Keywords: Blood–brain barrier opening; Diagnostic ultrasound imaging; Local drug release; Neuromodulation; Tumor therapy; Ultrasound contrast agent.

Fig. 1

a Basic schematic diagram of the modern medical ultrasound imaging system, b a typical ultrasound Doppler mode image, c the principle of ultrasound plane wave imaging, d typical ultrasound shear wave elastography, and e super-resolution blood flow imaging of mouse brain [65]

Fig. 2

Conceptual diagram showing the use of FUS exposure in the presence of MBs to open the BBB in CNS