title: Common carotid artery: variability of Doppler US velocity measurements.
abstract: OBJECTIVE
  To determine if Doppler ultrasound (US) measurements of systolic velocity in the common carotid artery vary markedly with distance from the bifurcation.
  
  
  METHODS
  Bilateral, insonation angle-corrected velocity was measured with US in the common carotid artery. Measurements were obtained 1, 2, 3, 4, and 5 cm from the carotid artery bifurcation in 20 volunteers (aged 25-43 years) with no history of neurologic or cardiovascular disease.
  
  
  RESULTS
  Velocity in the common carotid artery increased with distance (toward the aorta) from the bifurcation (mean increase, 9 cm/sec for each centimeter of distance from the bifurcation, up to the 4-cm distance; P < .001). Velocity increased more rapidly in subjects who were younger (P < .001) and in those with a lower pulse rate (P = .001).
  
  
  CONCLUSIONS
  The distance from the bifurcation at which common carotid artery velocity is measured should be standardized. This may increase the accuracy of the systolic velocity ratio for assessment of internal carotid artery stenosis and decrease some of the reported variability between different centers that perform US of the carotid artery.
authors.affiliation: Department of Diagnostic Radiology, Cleveland Clinic Foundation, OH 44195, USA.
authors.forename: J I
authors.initials: JI
authors.lastname: Meyer
authors.forename: R M
authors.initials: RM
authors.lastname: Khalil
authors.forename: N A
authors.initials: NA
authors.lastname: Obuchowski
authors.forename: L K
authors.initials: LK
authors.lastname: Baus
mesh_terms: D000328:Adult; D000367:Age Factors; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000502:physiology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D011674:Pulse / Q000502:physiology; D018608:Ultrasonography, Doppler / Q000592:standards