Fig. 1. Schematic layout of the key components of the optical imaging system.

Fig. 2. (a) Light scattering image under ambient light and (b) corresponding autofluorescence image under 670-nm excitation showing a rat containing malignant tumors in supine position (tumors #2 and 3). The spectral window for image formation was at 800-nm in both images. The hair represents the very bright regions visible on the fluorescence image outside the area of interest. On the fluorescence image (b), the tumor (indicated by the black arrow), spontaneously emits more fluorescence than adjacent normal mammary tissue (white arrow).

Fig. 3. (a) Light scattering image under ambient light and (b) corresponding autofluorescence image under 670-nm excitation and detection at 800-nm showing a rat containing a benign tumor in supine position (tumor #7). In the fluorescence image (b), the tumor (white arrow) is on the contrary to Fig. 2, much less fluorescent than the adjacent normal mammary tissue (black arrow). This tumor was shown to be a benign fibroadenoma on pathology. The signal intensity ratio T/N was in this case 0.22. Note the visibility of a blood vessel, absorbing light (black arrowheads), outlined by the brighter normal tissue. Small variation in the autofluorescence intensity in the normal tissue area is attributed to the presence of various organs of the animal located below the surface that exhibit different autofluorescence intensities under the deeply propagating excitation light.

Fig. 4. Tumor-to-normal signal intensity ratio plotted according to size for benign (엯) and malignant (Δ) tumors.