Composite ex vivo images (white field image superimposed with the fluorescence intensity) of lungs from mice bearing metastatic B16F-10 lung melanoma tumor. Left: two mice not injected with 2C5 QD-Mic. We see the clusters of melanoma cells (black) in the lungs (white) and a low level of near infrared fluorescence. Center: two mice injected with 2C5 QD-Mic at one hour after the injection. There is a higher level of near infrared fluorescence from the lungs. Right: two mice injected with 2C5 QD-Mic at twenty-four hours after the injection. The fluorescence originates mainly from sites around the melanoma clusters allows detection of the metastatic sites.