Process in targeted contrast agents for cancer imaging

The application of medical imaging technology is playing an important role in diagnosis and treatment of cancer. In clinic, the most commonly used imaging technology to detect cancers are X-ray computed tomography, nuclide imaging, magnetic resonance imaging and near-infrared fluorescence imaging. Contrast agents could enhance imaging signals and increase the sensitivity and accuracy of cancer detection. Neverthness, most of clinically used contrast agents have problems such as short retention time and tumor targeting insufficient, which is not favorable to cancer detecting. So it is of great significance to develop tumor targeting contrast agents. Currently, targeting strategies are divided into three types: passive targeting, active targeting and activatable targeting. In this review, we conclude the recent progress and applications of tumor targeting contrast agents of different imaging modilities. Besides, the future development of tumor targeting contrast agents is also prospected.