title: Interobserver, interequipment and intersubject variability of echo-Doppler examination of the common carotid and vertebral arteries.
abstract: OBJECTIVE
  We evaluated interobserver and interequipment variability in common carotid and vertebral flow measurements, using seven female members of nursing staff as subjects, four different ultrasound machines and three different radiologists as operators.
  
  
  METHODS
  The flow of the common carotid and vertebral arteries in each subject was examined at 0, 10, 20 and 30 min after lying down in a supine position. Peak velocity, end-diastolic velocity, mean velocity, systolic acceleration, cross-sectional area of the vessel, flow volume/min, resistance index and Doppler angle were measured.
  
  
  RESULTS
  A large proportion of the variance of peak velocity, cross-sectional area of the vessel and flow volume was patient-related. Significantly different values of end-diastolic velocity, mean velocity, resistance index, Doppler angle and systolic acceleration were obtained with different equipment. Significantly different values of systolic acceleration, vertebral peak velocity, common carotid artery flow and Doppler angle were obtained by different operators. However, part of the variability may be physiological due to the study protocol.
  
  
  CONCLUSIONS
  The use of the same operator and equipment is recommended in follow-up examinations.
authors.affiliation: Department of Diagnostic Radiology, University of Oulu, FIN-90220 Oulu, Finland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Päivänsalo
authors.forename: I
authors.initials: I
authors.lastname: Suramo
authors.forename: J
authors.initials: J
authors.lastname: Merikanto
authors.forename: E L
authors.initials: EL
authors.lastname: Lindholm
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology*; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D015588:Observer Variation; D018616:Ultrasonography, Doppler, Duplex / Q000295:instrumentation*; D014711:Vertebral Artery / Q000000981:diagnostic imaging*