The differentiation of certain structures from nearby tissues during medical imaging requires a sufficient amount of signals from the targeted area. The limitations of conventional contrast agents prevent the possibility of quick and accurate diagnosis of some cases and cause many problems for the patients and society. However, most of these restrictions can be surpassed through the unique physico-chemical characteristic nanotechnologyology and nano structures. Nanocarriers are abled to take the role of contrast agents or even provide the efficient delivery of these agents as carriers, while the capability of nanostructures in facilitating the simultaneous transportation of diagnostic and therapeutic agents is also undeniable. Thanks to the modern application of nanotechnology, it is possible to perform the targeted distribution of diagnostic and therapeutic agents to the desired locations. The status of in vivo surveillance and targeting efficiency can be improved by exploiting the potential benefits of nanoparticles and therefore, it is quiet expected to witness interesting characteristics from nanocarrier imaging agents for the diagnosis and staging of different diseases. This work presents a summary on the most common contrast agent nanostructures in medical imaging.