DETERMINATION OF HUMAN CORONARY-ARTERY COMPOSITION BY RAMAN-SPECTROSCOPY

Background We present a method for in situ chemical analysis of human coronary artery using near-infrared Raman spectroscopy. It is rapid an d accurate and does not require tissue removal; small volumes, approxi mate to 1 mm(3), can be sampled. This methodology is likely to be usef ul as a tool for intravascular diagnosis of artery disease. Methods an d Results Human coronary artery segments were obtained from nine ex-pl anted recipient hearts within 1 hour of heart transplantation. Minces from one or more segments were obtained through grinding in a mortar a nd pestle containing liquid nitrogen. Artery segments and minces were excited with 830 nm near-infrared light, and Raman spectra were collec ted with a specially designed spectrometer. A model was developed to a nalyze the spectra and quantify the amounts of cholesterol, cholestero l esters, triglycerides and phospholipids, and calcium salts present. The model provided excellent fits to spectra from the artery segments, indicating its applicability to intact tissue. In addition, the mince s were assayed chemically for lipid and calcium salt content, and the results were compared. The relative weights obtained using the Raman t echnique agreed with those of the standard assays within a few percent age points. Conclusions The chemical composition of coronary artery ca n be quantified accurately with Raman spectroscopy. This opens the pos sibility of using histochemical analysis to predict acute events such as plaque rupture, to follow the progression of disease, and to select appropriate therapeutic interventions.