Microparticles useful as ultrasonic contrast agents

摘要

Microparticles are provided comprising a shell of an outer layer of a biologically compatible material and an inner layer of biodegradable polymer. The core of the microparticles contain a gas, liquid or solid for use in drug delivery or as a contrast agent for ultrasonic contrast imaging. The microparticles are capable of passing through the capillary systems of a subject.