476 nm excited laser-induced fluorescence spectroscopy of human coronary arteries: applications in cardiology.

We have shown that normal coronary arteries and noncalcified and calcified atherosclerotic plaque can be differentiated on the basis of the 476 nm excited fluorescence spectra, providing the basis of a spectroscopic guidance system for coronary artery laser angiosurgery. This discrimination is based on extraction of parameters from tissue fluorescence spectra, which are proportional to the tissue concentrations of structural proteins (collagen and elastin) and ceroid via a model of tissue fluorescence. We use these parameters to calculate the likelihood that an area of interest in a coronary artery is normal, noncalcified, or calcified plaque. This method of diagnosing atherosclerosis provides information about the histochemical composition of atherosclerotic lesions and is thus fundamentally different from the diagnostic methods currently used. It may ultimately have bearing on a number of pertinent clinical problems. We have discussed applications to studying initiating factors in formation and progression of plaque, healing after interventional treatments, and the likelihood of restenosis after PTCA.