Image Guided Focused Ultrasound as a New Method of Targeted Drug Delivery
The field of image guided drug delivery has attracted significant interest for researchers from various disciplines. Imaging is used to guide ultrasound to mediate drug delivery improving drug disposition and achieve tissue or organ specific delivery. Targeting drug delivery can be largely beneficial for diseases usually treated with cytotoxic drugs such as chemotherapy or drugs that may affect healthy functions of organs or cells. The term “focal” drug delivery has been introduced to describe the focal targeting of drugs in specific regions with the help of imaging. An example of this method is the use of imaging and a novel non-invasive technique named focused ultrasound (FUS) in combination with Magnetic Resonance Imaging (MRI). The increased temperature induced by FUS (hyperthermia) can improve blood supply in tissues and therefore improve drug distribution. FUS has also been studied for effects on physiological barrier permeability such as the blood brain barrier (BBB). FUS has been utilised in combination with imaging and theranostics, such as labelled liposomes that respond to temperature increase. This strategy aims to trigger nanoparticles to release their cargo locally when hyperthermia is induced by FUS. MRI guided FUS drug delivery can improve drug bioavailability at targeted tissues and therefore improve the therapeutic profiles of drugs. This strategy can be translated to the clinic as MRgFUS is an established clinically approved approach. However, more basic research is required to understand its physiological mechanisms.