title: Photodynamic therapy for esophageal lesions: selectivity depends on wavelength, power, and light dose.
abstract: BACKGROUND
  Photodynamic therapy with 5-aminolevulinic acid-induced photosensitization could selectively eliminate esophageal epithelial lesions. This study aimed at optimizing laser parameters for 5-aminolevulinic acid photodynamic therapy of the normal rat esophagus.
  
  
  METHODS
  Sixty rats received 200 mg/kg 5-aminolevulinic acid orally and were illuminated 3 hours later with either 633 or 532 nm light (n = 30 for each group) through an endoesophageal balloon catheter. Rats received either 8.3 or 25 J/cm diffuser, applied with a 33, 100, or 300 mW/cm diffuser. During illumination, tissue fluorescence measurements and light dosimetry were done. Rats were sacrificed at 48 hours after photodynamic therapy.
  
  
  RESULTS
  During illumination, protoporphyrin IX fluorescence declined faster when a higher power output was used. Fluence rate at the esophageal surface was highest for 633-nm light. At 532 nm, light caused less damage to the epithelium and muscle than 633-nm light. Illumination with 33 mW resulted in selective epithelial ablation, whereas illumination with 300 mW caused muscle damage with minor epithelial damage.
  
  
  CONCLUSIONS
  The assumed selective epithelial damage of 5-aminolevulinic acid photodynamic therapy in the esophagus largely depends on the combination of wavelength, power, and light dose applied. Most selective epithelial damage was found when low-power 633-nm light was used.
authors.affiliation: Laboratory for Experimental Surgery, Erasmus University, Rotterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: van den Boogert
authors.forename: H J
authors.initials: HJ
authors.lastname: van Staveren
authors.forename: R W
authors.initials: RW
authors.lastname: de Bruin
authors.forename: J H
authors.initials: JH
authors.lastname: Eikelaar
authors.forename: P D
authors.initials: PD
authors.lastname: Siersema
authors.forename: R
authors.initials: R
authors.lastname: van Hillegersberg
mesh_terms: D000622:Aminolevulinic Acid; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000473:pathology; D004938:Esophageal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D004947:Esophagus / Q000187:drug effects / Q000473:pathology; D006414:Hematoporphyrin Photoradiation; D011230:Precancerous Conditions / Q000188:drug therapy* / Q000473:pathology; D051381:Rats; D016896:Treatment Outcome
chemical_list: D000622:Aminolevulinic Acid