Combining two or more different imaging modalities in the same agent can be of considerable value in molecular imaging. We describe the use of
streptavidin nanoparticle-based complexes as multimodality imaging agents to achieve
tumor detection in a mouse model by both fluorescence and nuclear imaging. Up to four biotinylated functionalities can be readily attached to these
streptavidin nanoparticles without apparent influence on their properties and with reasonable pharmacokinetics and therefore may be ideally suited for multimodality imaging. By binding a biotinylated anti-Her2
Herceptin antibody to provide
tumor targeting, a biotinylated
DOTA chelator labeled with (111)ln and a biotinylated
Cy5.5 fluorophore to a
streptavidin nanoparticle, we demonstrated multimodality imaging in SUM190 (Her2+)
tumor bearing mice on both an IVIS fluorescence camera and a NanoSPECT/CT small animal
nuclear camera. The imaging results show high
tumor accumulation and strong
tumor-to-normal tissue contrast by both fluorescence and nuclear imaging. The subsequent biodistribution study confirmed the specific
tumor accumulation in that
tumor accumulation of radioactivity at 40 h was 21 ID%/g and therefore much higher than all other tissues including liver, heart, kidney, spleen, and muscle that accumulated 8.7, 2.5, 6.9, 7.2, and 1.9 ID%/g, respectively. In conclusion, the
streptavidin nanoparticle under development in this laboratory was used effectively for multimodality imaging of
tumor in mice by fluorescence and nuclear detection. Presumably, other imaging modalities could also be considered.