Present invention relates to a dual-modal imaging (magnetic resonance and ultrasound)-guided drug vehicle and system, which possess encapsulation of hydrophobic drug and ultrasound-triggered release function. In the delivery system of the invention, the drug vehicle carrying certain drug (or drugs) is detectable by magnetic resonance imaging, and the release of drug is triggered by ultrasonication when the drug vehicle arrives at target site and accumulates to a desirable concentration. The MRI-guided drug delivery system provides improved accuracy of drug releasing, including position and timing.
