Molecular imaging is used for earlier detection, characterization of disease and an earlier assessment of treatment efficacy through imaging molecular/cellular events in living organisms. Fluorescent materials, radioisotopes and MRI enhancers as imaging probes, are being used for optical imaging, PET and MRI respectively. Each imaging modality has advantages and limitations regarding sensitivity, resolution, and tissue penetration of signal. Triple modal imaging combining PET/MRI/fluorescent probes will overcome the limitations of each modality. Recent advances in nanobiotechnology have identified many candidate probes for medical applications. Nanoparticles are able to carry fluorescent dyes, radioisotopes, drugs, genes, and targeting biomarkers. Triple modal nanoparticles could apply to sentinel node imaging by combined PET/MRI scanner for surgical plan and then to sentinel node detection by surgeons’ view. Furthermore, if targeting function is added to multimodal nanoparticles as molecular probes, they are able to be used for diagnosis In vitro and In Vivo, as well as therapeutic purposes. If nanotechnology and molecular imaging is combined, it could guide surgeons for minimal invasive but accurate surgery and physicans for personalized target therapy by validating the targeting efficiency using multimodal In Vivo imaging.