Characterization of human coronary artery atherosclerotic plaque fluorescence emission

Preliminary trials using fluorescence guidance of laser ablation in femoral arteries have been successful. There have, however, been few studies of the characteristics of fluorescence emissions from coronary arteries. A large series of fluorescence emission spectra from human coronary artery specimens was examined. Analysis included: fluorescence emission during excitation with ultraviolet and visible light; histologic correlations between plaque content and thickness, averaged spectra and fluorescence intensity ratios; and differences in specific plaque morphology with excitation of the same coronary specimens at 325 or 458 nm. Ratios of fluorescence emission intensity at selected wavelengths were calculated for both 325 and 458 nm excitation (13 wavelengths, 78 ratios for 325 nm; 11 wavelengths, 55 ratios for 458 nm). The following were found: atherosclerotic lesions in human coronary arteries were characterized by an increase in normalized fluorescence intensity at longer wavelengths when excited with either ultraviolet or visible light; calcific plaque content greater than 10% in lesions more than 1 mm thick was identified by increased normalized fluorescence intensity at 443 nm during excitation at 325 nm; and fatty plaque content correlated with fluorescence intensity ratios during 325 nm excitation, whereas fibrous and calcific content correlated well with fluorescence ratios during 458 nm excitation. It is concluded that characteristic fluorescence emission has the potential to correctly identify and characterize plaque morphology in human coronary arteries.