title: Monitoring the accumulation and dissipation of the photosensitizer protoporphyrin IX during standard dermatological methyl-aminolevulinate photodynamic therapy utilizing non-invasive fluorescence imaging and quantification.
abstract: 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 (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<0.05) than during the first treatment. No significant differences were noted in PpIX accumulation or dissipation during MAL-PDT when gender, age, lesion type and lesion surface area were considered.
  
  
  CONCLUSIONS
  It can therefore be concluded that PpIX fluorescence imaging can be used in real-time to assess PpIX 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 PpIX accumulation, which is subsequently fully utilized during light irradiation regardless of patient age, gender or lesion surface area.
authors.affiliation: Clinical Photobiology, Peninsula Medical School, University of Exeter, Royal Cornwall Hospital, Truro, Cornwall, UK.
authors.forename: Jessica
authors.initials: J
authors.lastname: Tyrrell
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Campbell
authors.forename: Alison
authors.initials: A
authors.lastname: Curnow
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000622:Aminolevulinic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D008856:Microscopy, Fluorescence / Q000379:methods*; D008875:Middle Aged; D009928:Organ Specificity / Q000187:drug effects; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D011524:Protoporphyrins / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012878:Skin Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D013050:Spectrometry, Fluorescence / Q000379:methods; D014018:Tissue Distribution / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D004338:Drug Combinations; D017319:Photosensitizing Agents; D011524:Protoporphyrins; C475457:methyl 5-aminolevulinate; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX