THERMAL-DAMAGE ASSESSMENT OF BLOOD-VESSELS IN A HAMSTER SKIN FLAP MODEL BY FLUORESCENCE MEASUREMENT OF A LIPOSOME-DYE SYSTEM

Background and Objectives: The present study was undertaken to evaluat e the feasibility of thermal damage assessment of blood vessels by usi ng laser-induced release of Liposome-encapsulated dye. Study Design/Ma terials and Methods: Experiments were performed in a hamster skin flap model. Laser irradiation was achieved with a 300 mu m fiber connected to a 805 nm diode laser (power=0.8W, spot diameter=1.3 mm and pulse e xposure time lasting from 1 to 6 s) after potentiation using a specifi c indocyanine green (ICG) formulation (water and oil emulsion). Liposo mes-encapsulated carboxyfluorescein were prepared by the sonication pr ocedure. Carboxyfluorescein (5,6-CF) was loaded at high concentration (100 mM) in order to quench its fluorescence. The measurements were pe rformed after i.v. injection of DSPC liposomes (1.5 ml) and lasted 40 min. Fluorescence emission was measured with an ultra high sensitivity intensified camera. Results: Three different shapes of fluorescent sp ots were identified depending on target (blood vessel or skin) and ene rgy deposition in tissue: (i) intravascular fluorescence, (ii) transie nt low fluorescence circular spot, and (iii) persistent high intense f luorescence spot, These images are correlated with histological data. Conclusion: Real-time fluorescence imaging seems to be a good tool to estimate in a non-invasive manner the thermal damage induced by a diod e laser combined with ICG potentiation. (C) 1997 Wiley-Liss, Inc.