Monitoring the accumulation and dissipation of the photosensitizer protoporphyrin IX during standard dermatological methyl-aminolevulinate photodynamic therapy utilizing non-invasive fluorescence imaging and quantification

Author's post-print is subject to a Creative Commons Attribution Non-Commercial No Derivatives LicenseBACKGROUND: Dermatological methyl-aminolevulinate photodynamic therapy (MAL-PDT) is utilized to successfully treat dermatological conditions. This study monitored fluorescence changes attributed to the accumulation and destruction of the photosensitizer, protoporphyrin IX (PpIX), at several different stages during the first and second treatments of clinical dermatological MAL-PDT. METHODS: A commercially available, non-invasive, fluorescence imaging system (Dyaderm, Biocam, Germany) was utilized to monitor fluorescence changes during the first and second MAL-PDT treatments in seventy-five lesions. RESULTS: The clinical data indicated statistically significant increases in fluorescence within lesions following the application of MAL for both treatments (P<0.001 and P<0.01 respectively) and subsequent statistically significant decreases in fluorescence within the lesions following light irradiation for both treatments (P<0.001 and P<0.01 respectively) whilst normal skin fluorescence remained unaltered. Lesions receiving a second treatment accumulated and dissipated significantly less PpIX (P