STUDY OF DIAGNOSIS CRITERIA FOR PATHOLOGICAL TISSUES BY LASER-INDUCEDFLUORESCENCE

It has been confirmed that the differences in fluorescence spectra of normal and pathological biotissues can be used as a sensitive and nond estructive diagnostic probe. However, experiments show that not only a re the fluorescence spectral features of different tissues very differ ent but the features of the same tissue under different detection cond itions are different too. Therefore, the diagnosis criteria of patholo gical tissues must be changed in accordance with different spectral fe atures. In this paper, several diagnosis methods using native fluoresc ence characteristics of biotissues given in existing reports are analy zed. With the fourth harmonic at 266 nm of a Q-switched YAG laser as a n excitation source, laser-induced fluorescence (LIF) spectra of nativ e human normal and pathological breast and blood vessel tissues in vit ro were measured and studied. According to their spectral characterist ics, two diagnosis criteria are suggested: by the fluorescence intensi ty ratios at several specific wavelengths, cancerous (with p < 0.001) and benign tumor (p < 0.005) can be distinguished from the normal tiss ue; by the fluorescence intensity ratios of the two main peaks, athero sclerotic plague and thrombus (both with p < 0.005) can be distinguish ed from normal blood vessel. In order to make comparisons with the res ults from human cancerous breast tissues, spectra of a model mouse wer e also observed.