Quantitative changes of collagen in human normal breast tissue and invasive ductal carcinoma using nonlinear optical microscopy

Multiphoton microscopy (MPM) imaging of collagen plays a key role in noninvasive diagnosis of human tissue. During the experiment, we observed an interesting phenomenon which two-photon excited fluorescence (TPEF) signal of collagen in human invasive ductal carcinoma of breast tissue becomes much weaker than the normal breast tissue, but the second harmonic generation (SHG) signal of collagen does not get an obvious change . In order to explain the phenomena,this paper emphasizes on the intensity of TPEF and SHG signal from collagen in human invasive ductal carcinoma of breast tissues and normal breast tissue. Further, we respectively obtain the intensity spectral information from collagen in the above two tissues with all parameter unaltered. Our quantitative results show that the intensity of TPEF from collagen in human invasive ductal carcinoma of breast tissue is much lower than the intensity of TPEF from collagen in normal breast tissue. According to the theoretic analysis, it was concluded that the intensity of TPEF declined due to the reduction of the quantum yield when the collagen was intruded by cancer cells. However, the invasion of cancer cells has no effect on decisive factor of SHG. Our theoretical analysis brings more detailed information about intensity of SHG and TPEF from collagen in the above two tissues.