Detection of ultrasound-sensitive nanodroplets with proton magnetic resonance spectroscopy

Motivation: Lipid nanodroplets can target drug delivery to specific regions of the brain using focused ultrasound, but methods to track their distribution and activity are needed. Goal(s): This study examined proton magnetic resonance spectroscopy as a method for monitoring nanodroplet delivery and changes following focused ultrasound. Approach: In vitro MRS provided a reference spectrum for the nanodroplets. In vivo, spectroscopy of the ultrasound target region was performed in rats at 7 T before and after nanodroplets were administered. Results: A peak at 1.15 ppm following nanodroplet and FUS administration was visible in vivo and corresponded to a prominent peak in the in vitro sample. Impact: Proton MRS has potential for monitoring the delivery of lipid nanodroplets in vivo. Nanodroplets can incorporate drugs and be targeted to specific brain regions using focused ultrasound. Future MRS studies will examine effects of drug release and dose on MRS.