CONICET | Buscador de Institutos y Recursos Humanos

Infrared imaging and In vivo spectrofluorometric analysis are non-invasive procedure that can be used to follow photodynamic therapy (PDT) of tumors. Infrared imaging detects radiation emitted by the tissue as a result of its temperature and produces a temperature field. The second technique analyzes the light emitted by the tissue containing a fluorescent photoactive drug. Using a thermal imaging camera (Agema 550) and portable spectrofluorometer with an excitation source emitting at 400 nm wavelength and a spectral analyzer ranging from 500 nm to 800 nm, the evolution of the m-tetrahydroxyphenyl chlorin (m-THPC) photosensitizer at the tumoral tissue of BALB/c murines with fibrosarcoma located at their flank was followed up. Thermal images were registered during the illumination while fluorescence was measured before, immediately after illumination and at interval of 24 h for 48 ? 256 h. We investigated the usefulness of both techniques for monitoring the extent of the photodynamic reaction in the tumor tissue illuminated with a light dose of 20 J/cm2 from a 637 nm LED lamp with an output of 1,06 W. The average fluorescence intensity in the tumor reached a maximum after 24 - 72 h. Subsequently, illuminations 24, 48, 72 and 96 h post-injection were performed, and the fluorescence was measured immediately before and after each illumination, observing in average a decrease in the intensity. Eventually, 24 h post-illumination, the fluorescence at certain parts of the tumor increased in comparison with that measured immediately after illumination. Temperature monitoring revealed non-uniform temperature distribution in the illuminated areas. The temperature gradually increased in the presence of photosensitizer in comparison with control mice. During the PDT temperature increase from 28,7°C to 35,2 °C. The use of both techniques allows a more confident evaluation of the PDT treatment and is expected to contribute to improve protocols for PDT application.