title: Reproducibility of non-invasive assessment of skin endothelial function using laser Doppler flowmetry and laser speckle contrast imaging.
abstract: BACKGROUND
  Endothelial dysfunction precedes atherosclerosis. Vasodilation induced by acetylcholine (ACh) is a specific test of endothelial function. Reproducibility of laser techniques such as laser-Doppler-flowmetry (LDF) and Laser-speckle-contrast-imaging (LSCI) to detect ACh vasodilation is debated and results expressions lack standardization. We aimed to study at a 7-day interval (i) the inter-subject reproducibility, (ii) the intra-subjects reproducibility, and (iii) the effect of the results expressions over variability.
  
  
  RESULTS
  Using LDF and LSCI simultaneously, we performed two different ACh-iontophoresis protocols. The maximal ACh vasodilation (peak-ACh) was expressed as absolute or normalized flow or conductance values. Inter-subject reproducibility was expressed as coefficient of variation (inter-CV,%). Intra-subject reproducibility was expressed as within subject coefficients of variation (intra-CV,%), and intra-class correlation coefficients (ICC). Fifteen healthy subjects were included. The inter-subject reproducibility of peak-ACh depended upon the expression of the results and ranged from 55% to 162% for LDF and from 17% to 83% for LSCI. The intra-subject reproducibility (intra-CV/ICC) of peak-ACh was reduced when assessed with LSCI compared to LDF no matter how the results were expressed and whatever the protocol used. The highest intra-subject reproducibility was found using LSCI. It was 18.7%/0.87 for a single current stimulation (expressed as cutaneous vascular conductance) and 11.4%/0.61 for multiple current stimulations (expressed as absolute value).
  
  
  CONCLUSIONS
  ACh-iontophoresis coupled with LSCI is a promising test to assess endothelial function because it is reproducible, safe, and non-invasive. N°: NCT01664572.
authors.affiliation: Laboratory of Vascular Investigations, University Hospital, Angers, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Puissant
authors.forename: Pierre
authors.initials: P
authors.lastname: Abraham
authors.forename: Sylvain
authors.initials: S
authors.lastname: Durand
authors.forename: Anne
authors.initials: A
authors.lastname: Humeau-Heurtier
authors.forename: Sébastien
authors.initials: S
authors.lastname: Faure
authors.forename: Georges
authors.initials: G
authors.lastname: Lefthériotis
authors.forename: Pascal
authors.initials: P
authors.lastname: Rousseau
authors.forename: Guillaume
authors.initials: G
authors.lastname: Mahé
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology; D000328:Adult; D003287:Contrast Media; D003952:Diagnostic Imaging / Q000379:methods*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D007478:Iontophoresis; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012867:Skin / Q000098:blood supply* / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D003287:Contrast Media; D000109:Acetylcholine