Fluorescence diagnostics and kinetic studies in the head and neck region utilizing low-dose XXXX sensitization.

@entity1 @entity5 @entity7170 @entity13880 @entity8454
Diagnostic measurements and pharmacokinetic studies were performed in 17 @entity1 with various kinds of malignant, premalignant and benign lesions in the head and neck region by means of point monitoring laser-induced fluorescence. For marking different types of tissue, @entity8454 (ALA)-induced @entity13880 ( @entity13880 ) was used. The ALA-induced @entity13880 synthesis was monitored at different time intervals after oral administration of ALA in low doses, 5 and 15 mg/kg b.w. Besides the @entity7170 -related signal the tissue endogenous fluorescence was also recorded. The fluorescence spectra were evaluated at two different wavelengths corresponding to the specific drug-related fluorescence peak and the endogenous tissue fluorescence emission at 635 and 490 nm, respectively. The evaluated fluorescence data were correlated to the histopathological tissue investigation. A fall-off in the overall fluorescence intensity at 490 nm was obtained for all the malignant and premalignant areas, as well as an increased red fluorescence. A ratio between the red and the blue/green fluorescence intensity was formed for each time interval after the ALA administration. The lower drug dose seems to be sufficient to obtain a useful demarcation ratio between normal and diseased tissue with a very low @entity13880 fluorescence intensity in the normal tissue. A @entity13880 fluorescence maximum seems to occur between 3 and 4 h in normal tissues, whereas @entity5 tissue shows a higher level for a longer period of time.
