Comparison between the NASCET method and subjective visual impression in the evaluation of internal carotid artery stenosis.
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.
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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
André
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Azevedo
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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