Novel ultrasound contrast agents are provided which are covalently linked to a bioorthogonal reactive group, and optionally further coupled to a corresponding bioorthogonal reactive group coupled with a targeting entity. Methods for targeted ultrasound imaging using such contrast agents are also provided comprising the steps of: 1) injecting the contrast agent into a patient and imaging the patient at a site of interest to detect the contrast agent, wherein the detection of the contrast agent indicates the presence of a target within the patient.
