title: Real-time, in vivo measurement of tissular pO2 through the delayed fluorescence of endogenous protoporphyrin IX during photodynamic therapy.
abstract: Tissular oxygen concentration plays a key role during photodynamic therapy (PDT). Therefore, monitoring its local oxygen partial pressure (pO2) may help predict and/or control the outcome of a PDT treatment. The first real-time, in vivo measurements of the pO2 in the chicken egg’s chorioallantoic membrane, using the delayed fluorescence of photoactivable porphyrins (PAPs), including protoporphyrin IX (PpIX), as monitored with a dedicated optical, fiber-based, time-resolved spectrometer, are reported here. The formation of PAPs/PpIX, photosensitizers of extensive clinical use, was induced in the chicken egg’s chorioallantoic membrane (CAM) with aminolevulinic acid. An excellent correlation between the vascular damage induced by PDT and the reduction in tissular pO2 is found. This study suggests that clinical measurement of the pO2 using the PAPs’/PpIX’s delayed fluorescence (DF) may be used to individualize in real time the PDT light dose applied.
authors.affiliation: Medical Photonics Group, Swiss Federal Institute of Technology, SB-ISIC, Station 6, Lausanne, Switzerland.
authors.forename: Filippo
authors.initials: F
authors.lastname: Piffaretti
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Novello
authors.forename: Rajendran Senthil
authors.initials: RS
authors.lastname: Kumar
authors.forename: Eddy
authors.initials: E
authors.lastname: Forte
authors.forename: Cédric
authors.initials: C
authors.lastname: Paulou
authors.forename: Patrycja
authors.initials: P
authors.lastname: Nowak-Sliwinska
authors.forename: Hubert
authors.initials: H
authors.lastname: van den Bergh
authors.forename: Georges
authors.initials: G
authors.lastname: Wagnières
mesh_terms: D000287:Administration, Topical; D000622:Aminolevulinic Acid / Q000008:administration & dosage; D000818:Animals; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D005453:Fluorescence; D007700:Kinetics; D055620:Optical Phenomena; D010100:Oxygen / Q000378:metabolism*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000378:metabolism*; D011524:Protoporphyrins / Q000737:chemistry* / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D010100:Oxygen