title: Monitoring microcirculatory alterations in oral squamous cell carcinoma following photodynamic therapy.
abstract: BACKGROUND
  One of the mechanisms through which photodynamic therapy (PDT) is thought to elicit tumour destruction is by producing microvascular damage and obstruction of nutritive blood flow. The aim of this study was to directly monitor and quantify microcirculatory changes following tissue illumination by PDT for oral squamous cell carcinoma.
  
  
  METHODS
  Ten consecutive patients receiving PDT for a carcinoma in situ, a T1 or T2 tumour in the oral cavity without evidence of lymph node metastasis were selected for this study. Tumour and marginal healthy mucosa total capillary density (TCD) and functional capillary density (FCD) inside the field of illumination were measured and compared using sidestream dark-field (SDF) imaging prior to tissue illumination, immediately after PDT, and again after 15min.
  
  
  RESULTS
  Baseline mean tumour TCD was 21.2±5capillaries per square millimetres (cpll/mm²) and 24.9±19cpll/mm² in the surrounding marginal healthy tissue; there were no significant differences between tumour and healthy tissue or time points. Comparisons between baseline and post-illumination time points revealed significant differences in both tumour and healthy tissue FCD (P<0.05). No significant differences in FCD were observed between the two tissues.
  
  
  CONCLUSIONS
  Our findings using SDF imaging demonstrate that PDT significantly attenuates tumour and marginal healthy tissue perfusion by directly disrupting the functionality of the microcirculation.
authors.affiliation: Department of Translational Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. D.M.Milstein@amc.uva.nl
authors.forename: Dan M J
authors.initials: DM
authors.lastname: Milstein
authors.forename: Anne-Marije
authors.initials: AM
authors.lastname: van Kuijen
authors.forename: Marcel P
authors.initials: MP
authors.lastname: Copper
authors.forename: Barış
authors.initials: B
authors.lastname: Karakullukçu
authors.forename: I Bing
authors.initials: IB
authors.lastname: Tan
authors.forename: Jérôme A H
authors.initials: JA
authors.lastname: Lindeboom
authors.forename: Wytske J
authors.initials: WJ
authors.lastname: Fokkens
authors.forename: Can
authors.initials: C
authors.lastname: Ince
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000187:drug effects*; D008875:Middle Aged; D009055:Mouth / Q000098:blood supply; D009062:Mouth Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000503:physiopathology; D018307:Neoplasms, Squamous Cell / Q000098:blood supply / Q000188:drug therapy* / Q000503:physiopathology; D010778:Photochemotherapy / Q000379:methods*