In-vivo NIR autofluorescence of rat mammary tumors discriminates pathological malignancy

摘要

Benign and malignant mammary tumors were induced in rats using a potent carcinogen, N-ethyl-N-nitrosurea (ENU). Induced tumors were examined under near-infrared (NIR) fluorescence imaging (excitation wavelength 670-730 nm, detection wavelength 750-800 nm) to search for a difference in the photophysical properties of the tumors reflecting their pathologic status. Three benign and eight malignant tumors were examined optically and pathologically. The non-enhanced optical images showed a significantly lower (P<0.05) spontaneous fluorescent signal in the benign tumors than in their malignant counterparts. The precise chemical origin for the observed differences in tumor autofluorescence remains undetermined. It can be hypothesized that the reported high concentration of porphyrins, NIR-fluorescing compounds, in the malignant lesions, could account for the observed increased autofluorescence.