Treatment of disease can only be effective when timely and accurate diagnosis of the pathology is achieved. More precise diagnosis can be accomplished if the underlying molecular processes involved in the pathology can be imaged in vivo. This is the field of molecular imaging, which aims to visualize cellular function and molecular processes in living organisms in a non-invasive way. With that aim, molecular markers are specifically targeted by imaging contrast agents. Molecular MRI needs powerful targeted contrast agents. For that purpose, target-specific gadolinium-containing paramagnetic and superparamagnetic, iron oxide-based micelles have been developed. Micelles are lipid-based nanoparticles which are biocompatible and carry a high payload of MR contrast-generating agent. The coupling of high-affinity ligands makes the micelles target-specific. Additionally, this lipid-based micelle platform allows for incorporation of contrast generating molecules for other imaging modalities, e.g., fluorescence or nuclear imaging. This permits applications for multiple imaging modalities, making micelles a highly versatile contrast agent.