title: Validation of an automated method for assessing brachial artery endothelial dysfunction.
abstract: BACKGROUND
  Endothelial dysfunction is an early finding in diverse vascular diseases and can be measured noninvasively using brachial ultrasound. There is great interest in the potential use of this parameter for assessing interventions or cardiovascular prognosis. Automated image analysis of the ultrasound images would facilitate implementation of such measurements in high throughput clinics and/or large clinical trials.
  
  
  OBJECTIVE
  To compare a new method designed to assess brachial artery diameter and percentage diameter changes through automated, beat-by-beat image processing (Brachial Tools, Medical Imaging Applications, USA), with a nonautomated method (Prosound System, Jet Propulsion Laboratory, USA).
  
  
  METHODS
  Brachial ultrasound tapes from 12 patients undergoing endothelial function assessment using forearm cuff-occlusion, measurement of flow-mediated dilation and responses to nitroglycerin were analyzed by both methods.
  
  
  RESULTS
  The correlation between the two systems was excellent for both the measurement of absolute diameters (r=0.995, P<0.001) and percentage diameter changes (r=0.973, P<0.001). The automated method demonstrated no bias compared with the frame-by-frame method and excellent precision (0.07 mm and 1.62 percentage diameter change).
  
  
  CONCLUSIONS
  The automated method provides valid data while substantially diminishing analysis time.
authors.affiliation: Cardiac Imaging Research Laboratory, Jack Bell Research Centre, Atherosclerosis Reversal Clinic, St Paul's Hospital, University of British Columbia, Vancouver. mancini@interchange.ubc.ca
authors.forename: G B John
authors.initials: GB
authors.lastname: Mancini
authors.forename: Eunice
authors.initials: E
authors.lastname: Yeoh
authors.forename: David
authors.initials: D
authors.lastname: Abbott
authors.forename: Sammy
authors.initials: S
authors.lastname: Chan
mesh_terms: D000328:Adult; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D005996:Nitroglycerin / Q000494:pharmacology; D013223:Statistics as Topic; D014463:Ultrasonography; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin