title: Comparison between the NASCET method and subjective visual impression in the evaluation of internal carotid artery stenosis.
abstract: OBJECTIVE
  To evaluate the accuracy of subjective visual impression (SVI) of an experienced neuro-radiologist in the measurement of the degree of internal carotid artery (IC) stenosis evaluated by digital angiography (DGA).
  
  
  METHODS
  Ten symptomatic patients with internal carotid stenosis greater than 70% in a previous duplex scan were submitted to DGA. The degree of stenosis in both sides (symptomatic and asymptomatic) were evaluated by the same neuro-radiologist who gave his SVI and applied the NASCET method immediately after. Both methods were compared using the intraclass correlation coefficient (r) and its 95% confidence interval (95% ci). For each method, the sample (20 ICs) was also divided in surgical (stenosis between 70 and 99%) and non surgical ICs, using kappa concordance coefficient (k) to compare the results.
  
  
  RESULTS
  The results comparing the 20 values obtained by each method are: r = 0.90 (95% ci: 0.77-0.96). Dividing the sample in surgical and non surgical ICs, k = 0.857, p < 0.0001; sensitivity = 100% (39.6%-100%); specificity = 93.8% (67.7%-99.7%); positive predictive value = 80% (29.9%-98.9%); negative predictive value = 100% (74,7%-100%).
  
  
  CONCLUSIONS
  The SVI may be used by at least some experienced neuroradiologists as a preliminary tool to evaluate the degree of IC stenosis with DGA, but a standardised and well established method should be routinely performed.
authors.affiliation: Neurological Service, Department of Internal Medicine, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. marcopy@uninet.com.br
authors.forename: M O
authors.initials: MO
authors.lastname: Py
authors.forename: C
authors.initials: C
authors.lastname: André
authors.forename: F S
authors.initials: FS
authors.lastname: Azevedo
mesh_terms: D015901:Angiography, Digital Subtraction / Q000592:standards*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000601:surgery; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000601:surgery; D016001:Confidence Intervals; D016894:Endarterectomy, Carotid; D006801:Humans; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014463:Ultrasonography