AUTOFLUORESCENCE SPECTROSCOPY USING A XECL EXCIMER-LASER SYSTEM FOR SIMULTANEOUS PLAQUE ABLATION AND FLUORESCENCE EXCITATION

Laser-induced fluorescence may be used to guide laser ablation of athe rosclerotic lesions. This study was performed to evaluate arterial aut ofluorescence spectroscopy in vitro using a single XeCl excimer laser (308 nm) for simultaneous tissue ablation and fluorescence excitation. The laser beam was coupled to a 600-mum silica fiber transmitting 40- 50 mJ/mm2 per pulse. The fluorescence radiation emanating retrogradely from the fiber was collected by a concave mirror for spectroscopic an alysis over a range of 321-657 nm. The arterial media (n = 26), lipid plaques (n = 26), and calcified lesions (n = 27) of aortic specimens f rom ten human cadavers were investigated in air, saline, and blood. Wh ereas the spectrum of calcified lesions changed with the surrounding o ptical medium, the other spectra remained constant. In air and blood, the spectra of arterial media, lipid plaques, and calcified lesions co uld be differentiated qualitatively and quantitatively (P < 0.0001). I n saline, there was no clearcut spectroscopic difference between lipid plaques and calcified lesions. However, normal arterial media and ath erosclerotic lesions (lipid plaques plus calcified lesions) could stil l be discriminated. Thus spectroscopy and plaque ablation can be combi ned using a single XeCl excimer laser. These encouraging results shoul d stimulate further studies to determine the potential use of this app roach to guide laser angioplasty in humans. (C) 1994 Wiley-Liss, Inc.