[Development of in vivo imaging system targeting a molecular marker]

Molecular imaging captures biological and biochemical processes in vivo through imaging probes, and can contribute to optimize cancer therapy through monitoring and predicting treatment effects. Many imaging probes targeting critical molecules in cancer development and therapy are being developed. In the development of molecular imaging methods, the critical steps are proper target selection, imaging probe design and synthesis, assessment of the imaging results in animal models, and, in case the imaging is for diagnosis, in clinical trials. In this article common strategies in the target selection and the probe design are outlined. Also, we present some examples of positron emission tomography(PET) and single photon emission tomography(SPECT)imaging probes and their targets, such as 3-[18F]fluoro-3-deoxythymidine( FLT)for cell proliferation, Cu-ATSM for hypoxia, RGD peptides for neovascularization, and kinase inhibitors and antibodies for membrane protein kinase receptors.