Disclosed herein are methods for delivering a drug to the brain of a subject and monitoring the distribution of the drug therein. The method includes steps of: (a) intranasally administering of a first and second liposomes respectively loaded with the drug and a computed tomography (CT) contrast agent therein to the subject; (b) subjecting the brain of the subject of step (a) to a magnetic resonance imaging (MRI) scan; and (c) measuring chemical exchange saturation transfer (CEST) signals during the MRI scan in both olfactory bulb (OB) and frontal lobe (FL) regions at 1.2 ppm, 4.3 ppm, and −3.4 ppm, respectively.