Complementarity of variable-magnification and spectral-separation fluorescence imaging systems for noninvasive detection of metastasis and intravital detection of single cancer cells in mouse models.

Imaging of tumor growth, progression and metastasis with fluorescent proteins in mouse models is a powerful technology. A limit to fluorescent-protein imaging has been for non-invasive deep-seated tumors, such as those in the lung. In the present study, the Maestro spectral-separation fluorescence imaging system and the OV100 variable-magnification imaging system were compared for noninvasive detection of metastasis in fluorescent protein-expressing orthotopic lung, liver, pancreas, and colon cancer in nude mouse tumor models, as well as for intravital single-cell imaging. Sensitivity, multispectral capability, contrast, and single cell resolution were investigated. The Maestro system outperformed the OV100 for noninvasive imaging of primary and metastatic tumors. The Maestro system detected brain tumor metastasis five days earlier than did the OV100. The Maestro had greater depth of detection compared with the OV100. By separating skin and food autofluorescence, the Maestro provided high-contrast images. The Maestro system was able to produce composite images with more unmixed components and detected more different color signals simultaneously than did the OV100. However, the OV100 system had higher resolution and was able to detect single cells in vivo unlike the Maestro. The present study demonstrates that the two instruments are complementary for imaging of all stages of cancer in mice, including single-cell trafficking and the superiority of in vivo fluorescent-protein imaging over luciferase imaging. Copyright