Excimer-laser-induced fluorescence spectroscopy of human arteries during laser ablation

摘要

The autofluorescence of human arterial tissue with varying degrees of atherosclerosis was studied in vitro to develop a diagnostic tool for tissue differentiation simultaneously to tissue ablation induced by a XeCl-excimer laser (wavelength 308 nm). Healthy vessel walls and artery segments containing lipid-rich or calcified areas were investigated in air, saline solution (0.9% NaCl), and in blood. The fluorescence spectra in the wavelength range from 320 nm to 650 nm were recorded with an optical multichannel analyzer, and they allowed for a clear discrimination between plaque and healthy vessel wall even in blood. For each single laser shot with an energy density of about 4-5 J/cm$+2$/, well above the ablation threshold, a complete spectrum was recorded. The fluorescence spectra were analyzed in terms of their contributions from normal arterial tissue, lipid-rich and calcified plaques. The results clearly show the feasibility of controlling the ablation process by fluorescence spectroscopy in order to avoid vessel-wall perforation which is one of the main drawbacks in laser angioplasty.