title: Standardized ultrasound evaluation of carotid stenosis for clinical trials: University of Washington Ultrasound Reading Center.
abstract: BACKGROUND
  Serial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and restenosis. The University of Washington Ultrasound Reading Center (UWURC) provides a uniform examination protocol and interpretation of duplex Doppler velocity measurements.
  
  
  METHODS
  Doppler waveforms from 6 locations along the common carotid and internal carotid artery path to the brain plus the external carotid and vertebral arteries on each side using a Doppler examination angle of 60 degrees are evaluated. The UWURC verifies all measurements against the images and waveforms for the database, which includes pre-procedure, post-procedure and annual follow-up examinations. Doppler angle alignment errors greater than 3 degrees and Doppler velocity measurement errors greater than 0.05 m/s are corrected.
  
  
  RESULTS
  Angle adjusted Doppler velocity measurements produce higher values when higher Doppler examination angles are used. The definition of peak systolic velocity varies between examiners when spectral broadening due to turbulence is present. Examples of measurements are shown.
  
  
  CONCLUSIONS
  Although ultrasonic duplex Doppler methods are widely used in carotid artery diagnosis, there is disagreement about how the examinations should be performed and how the results should be validated. In clinical trails, a centralized reading center can unify the methods. Because the goals of research examinations are different from those of clinical examinations, screening and diagnostic clinical examinations may require fewer velocity measurements.
authors.affiliation: D, Eugene Strandness Vascular Laboratory, Department of Surgery, University of Washington, Seattle, Washington 98195, USA. kwbeach@uw.edu
authors.forename: Kirk W
authors.initials: KW
authors.lastname: Beach
authors.forename: Robert O
authors.initials: RO
authors.lastname: Bergelin
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Leotta
authors.forename: Jean F
authors.initials: JF
authors.lastname: Primozich
authors.forename: P Max
authors.initials: PM
authors.lastname: Sevareid
authors.forename: Edward T
authors.initials: ET
authors.lastname: Stutzman
authors.forename: R Eugene
authors.initials: RE
authors.lastname: Zierler
mesh_terms: D000046:Academic Medical Centers / Q000379:methods*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D002986:Clinical Trials as Topic; D006801:Humans; D017410:Practice Guidelines as Topic / Q000592:standards*; D019114:Remote Consultation / Q000379:methods*; D015203:Reproducibility of Results; D018616:Ultrasonography, Doppler, Duplex / Q000592:standards*; D014861:Washington
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