Temperature variations of reflection, transmission, and fluorescence of the arterial wall

The variations of reflection and transmission coefficients, as well as of the fluorescence response of the arterial wall are studied as a function of temperature. In a first experiment, reflection coefficient, transmission coefficient, and temperature, are measured during laser irradiation of the tissue. The fluorescence spectrum is recorded in a second experiment, together with temperature, during heating of the arterial wall in a vapor bath. The temperature dependence of the optical parameters and of the fluorescence response are then deduced. For the reflection and transmission coefficients, a direct correlation of their variations with temperature is measured. Extrema are observed in the temperature region at about 50°C. A global decrease of the fluorescence intensity is characteristic of a temperature increase. These variations can be used as thermal markers, which in turn could give a criterion to control heat deposition in the tissue during laser anastomose.