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

摘要

Background: 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 (PplX), 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, Bio-cam, Germany) was utilized to monitor fluorescence changes during the first and second AAAL-PDT treatments in seventy-five lesions. Results: The clinical data indicated statistically significant increases in fluorescence within lesions following the application of AAAL 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 PplX (P＜0.05) than during the first treatment. No significant differences were noted in PplX accumulation or dissipation during MAL-PDT when gender, age, lesion type and lesion surface area were considered. Conclusions: It can therefore be concluded that PplX fluorescence imaging can be used in realtime to assess PplX levels during dermatological PDT. Similar observations were recorded from the three currently licensed indications indicating that the standard 'one size fits all' protocol currently employed appears to allow adequate PplX accumulation, which is subsequently fully utilized during light irradiation regardless of patient age, gender or lesion surface area.