The present invention relates to ultrasound contrast agent, like non-functionalised or functionalised microbubbles or non-functionalised or functionalised microparticles, for the use in diagnosis or as a pharmaceutical. In particular, the present invention relates to microdosing of functionalised microbubbles or functionalised microparticles for use in ultrasound diagnosis. In addition, the present invention relates to pharmaceutical or diagnostic compositions, in particular ultrasound contrast agents, containing functionalised microbubbles or functionalised microparticles at low dosage. Finally, the present invention relates to methods for the diagnosis, in particular, ultrasound diagnosis, and/or treatment of a subject using the functionalised microbubbles or functionalised microparticles in low dosage as defined herein.
