title: Determination of duplex Doppler ultrasound criteria appropriate to the North American Symptomatic Carotid Endarterectomy Trial.
abstract: OBJECTIVE
  The North American Symptomatic Carotid Endarterectomy Trail (NASCET) demonstrated the benefit of carotid endarterectomy for symptomatic patients with > or = 70% carotid stenosis. Screening for detection of significant carotid occlusive disease has relied on duplex Doppler imaging. However, traditional duplex categories (50% to 79%, 80% to 99%) are not directly applicable to NASCET. We sought to evaluate duplex criteria for determination of > or = 70% carotid stenosis.
  
  
  METHODS
  Duplex scan and arteriograms of 110 patients (210 carotids), performed within 1 month of each other, were reviewed by blinded readers. Arteriographic stenosis was determined by the NASCET method. Duplex measurements of peak systolic and end-diastolic velocity (PSV, EDV) were recorded, and ratios of velocities in the internal and common carotid arteries (ICA, CCA) were calculated. Receiver-operator characteristic (ROC) curves of sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy were determined.
  
  
  RESULTS
  Interobserver agreement for measurement of arteriographic stenosis was "almost perfect" (kappa=0.86). The criteria chosen for detection of > or = 70% stenosis were PSVICA>210 cm/s (sensitivity, 94%; specificity, 77%; PPV, 68% NPV, 96% accuracy, 83%) EDVICA>70 cm/s (sensitivity, 92%; specificity, 60%; PPV, 73%; NPV, 86%; accuracy 77%), PSVica/PSVCCA >3.0 (sensitivity, 91%; specificity, 78%; PPV, 70%; NPV, 94%; accuracy, 83%), and EDVICA/EDVCCA>3.3 (sensitivity, 100%; specificity, 65%; PPV, 65% NPV, 100%; accuracy, 79%).
  
  
  CONCLUSIONS
  We conclude that > or = 70% carotid stenosis can be reliably determined by duplex Doppler ultrasound. Individual vascular laboratories must validate their own results.
authors.affiliation: Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Carpenter
authors.forename: F J
authors.initials: FJ
authors.lastname: Lexa
authors.forename: J T
authors.initials: JT
authors.lastname: Davis
mesh_terms: D017536:Carotid Artery, Common; D002342:Carotid Artery, External; D002343:Carotid Artery, Internal; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000601:surgery; D002533:Cerebral Angiography; D016894:Endarterectomy, Carotid; D006801:Humans; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler