**6. Conclusions**

FT-IR spectra showed that hyperoxidation of lipids, phospholipids and membranes take place during atherogenesis. The plaque formation and the increase of LDL lead to change of tertiary structure of proteins from α-helix to random one. FT-IR spectra clearly revealed prominent spectral features corresponding to plaque constituents such as the presence of lipids, lipid esters, fibrous tissues and phosphate group (calcification). Spectral data were correlated well with patients' analyses. The present work demonstrates that infrared spectroscopy can be used to accurately estimate the chemical composition of coronary and carotid arteries. In vivo information about the chemical composition of atherosclerotic lesions may provide a powerful method to detect and characterize sites of atherosclerosis.
