title: Non-invasive assessment of endothelial function. Intra and inter-observer variability.
abstract: OBJECTIVE
  Non-invasive evaluation of endothelial function with high resolution ultrasound has become a widely accepted tool in determination of high risk subjects for early atherosclerosis. Despite its simple appearance, ultrasonographic assessment of brachial artery changes, is technically challenging and has a significant learning curve. In the present study, we evaluate the intra and inter-observer variability in assessing peripheral endothelial function with high resolution ultrasound at a tertiary referral center.
  
  
  METHODS
  Assessment of endothelial function was performed by 2 physicians in 20 volunteers without evidence of coronary artery disease. Endothelial function is evaluated with a high frequency bidimensional ultrasound with a 10.0-MHz linear-array transducer used for the study. Each volunteer was examined by both observers using an identical protocol, measuring brachial artery diameter on three occasions.
  
  
  RESULTS
  Excellent correlation was observed for all brachial artery measures with a Spearman's correlation coefficient > 0.9 (p < 0.0001). Flow-mediated dilation (FMD) in the study population was of 10.45+/-6.9%. Flow independent dilation (FID) was of 24.35+/-7.63%. Intra-observer variability was of 2.1% for observer A and 1.1 % for observer B.
  
  
  CONCLUSIONS
  Non-invasive assessment of endothelial function using brachial artery ultrasound is reproducible and can be performed with low intra and inter-observer variability.
authors.affiliation: Electrocardiology Department, Instituto Nacional de Cardiologia lgnacio Chávez, México, D.F
authors.forename: Arturo Sotomayor
authors.initials: AS
authors.lastname: González
authors.forename: Andrea
authors.initials: A
authors.lastname: Kostine
authors.forename: Jorge R
authors.initials: JR
authors.lastname: Gómez-Flores
authors.forename: Manlio F
authors.initials: MF
authors.lastname: Márquez
authors.forename: Antonio G
authors.initials: AG
authors.lastname: Hermosillo
authors.forename: Juan Verdejo
authors.initials: JV
authors.lastname: París
authors.forename: Pedro Iturralde
authors.initials: PI
authors.lastname: Torres
authors.forename: Luis Colín
authors.initials: LC
authors.lastname: Lizalde
authors.forename: Santiago Nava
authors.initials: SN
authors.lastname: Townsend
authors.forename: Manuel
authors.initials: M
authors.lastname: Cárdenas
mesh_terms: D000328:Adult; D001916:Brachial Artery / Q000000981:diagnostic imaging*; D003627:Data Interpretation, Statistical; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D014159:Transducers; D014463:Ultrasonography