Near-infrared autofluorescence imaging for detection of cancer

Near-infrared autofluorescence imaging of tissues under long-wavelength laser excitation in the green and red spectral region complemented by cross-polarized elastic light scattering was explored for cancer detection. Various types of normal and malignant human tissue samples were utilized in this investigation. A set of images for each tissue sample was recorded that consisted of two autofluorescence images obtained under 532- and 632.8-nm excitation and lightscattering images obtained under linearly polarized illumination at 700, 850, and 1000 nm. These images were compared with the histopathology of the tissue sample. The experimental results indicated that for various tissue types, the intensity of the autofluorescence integrated over the 700 to 1000-nm spectral region was considerably different in cancer tissues than in that of the contiguous nonneoplastic tissues. This difference provided the basis for the detection of cancer and delineation of the tumor margins. Variations on the relative intensity were observed among different tissue types and excitation wavelengths.