title: Fluorescence analysis of biochemical constituents identifies atherosclerotic plaque with a thin fibrous cap.
abstract: Vulnerable plaque generally contains a thin fibrous cap, lipid pools, and reduced internal plaque collagen. Arterial fluorescence analysis can differentiate atherosclerotic lesions from normal arteries; however, the contribution of the lipid core to atherosclerotic arterial fluorescence remains controversial. This study aimed to identify lipid core fluorophores and to differentiate the lipid core from normal artery and atheroma. The helium-cadmium laser-induced fluorescence spectra of cadaveric arteries and known chemical constituents were recorded. Lipid core fluorescence spectra exhibited marked red shifts and broadening compared with the fluorescence spectra of normal tissue and atheroma. Similar fluorescence spectra were obtained for lipid core and oxidized low density lipoprotein, for atheroma and collagen, and for normal artery and elastin. A classification based on collagen, elastin, and oxidized low density lipoprotein spectral decomposition could discriminate the lipid core (n=29), normal artery (n=74), atheroma (n=73), and preatheroma (n=10) with 86% accuracy. Fibrous cap thickness was correlated with the spectral collagen content index (r=0.65, P<0.0001), especially at a thickness of <200 microm. We conclude that a classification algorithm based on chemical spectral decomposition can accurately classify the fluorescence spectra of normal artery, atheroma, and lipid core and may be useful in identifying vulnerable atheroma in vivo.
authors.affiliation: Department of Internal Medicine I, National Defense Medical College, Saitama, Japan. karakawa@me.ndmc.ac.jp
authors.forename: Koh
authors.initials: K
authors.lastname: Arakawa
authors.forename: Kikuo
authors.initials: K
authors.lastname: Isoda
authors.forename: Toshimitu
authors.initials: T
authors.lastname: Ito
authors.forename: Kei
authors.initials: K
authors.lastname: Nakajima
authors.forename: Toshio
authors.initials: T
authors.lastname: Shibuya
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Ohsuzu
mesh_terms: D000328:Adult; D000465:Algorithms; D001157:Arterial Occlusive Diseases / Q000145:classification / Q000473:pathology; D002102:Cadaver; D003094:Collagen / Q000032:analysis; D003324:Coronary Artery Disease / Q000145:classification / Q000473:pathology*; D004549:Elastin / Q000032:analysis; D005263:Femoral Artery / Q000473:pathology*; D006801:Humans; D007834:Lasers; D008055:Lipids / Q000032:analysis; D008077:Lipoproteins, LDL / Q000032:analysis; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D010084:Oxidation-Reduction
chemical_list: D008055:Lipids; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D003094:Collagen; D004549:Elastin