COMPARISON OF ILLUMINATION WAVELENGTHS FOR DETECTION OF ATHEROSCLEROSIS BY OPTICAL FLUORESCENCE SPECTROSCOPY

Illumination wavelengths between 270 and 470 nm are evaluated to determine which wavelength produces the greatest difference between the fluorescence emission spectra of normal and atheromatous arterial tissues. Atherosclerotic plaques are considered as a diseased class and are further subdivided into three diseased subclasses-fibrous plaques, complicated plaques, and hard calcified plaques. The Mahalanobis distance squared, a statistical figure of merit describing class separability, is used to compare the illumination wavelengths. Classification accuracies are also estimated and used for comparison. Optimum classification performance is found to occur with illumination in the wavelength range 314 to 334 nm, except for hard calcified plaques, which are more accurately classified with illumination wavelengths longer than 380 nm. The issue of how much information is required from the fluorescence emission spectra to accurately classify tissue is also investigated.