A validity study of continuous Doppler

INTRODUCTION: Ultrasound is regularly used for the detection of carotid stenosis which can be treated surgically. This technique includes continuous Doppler, which together with study of blood flow in the orbit is very useful and should be used systematically, not only in certain cases. We present a study of the usefulness of this technique in our Cerebral Vascular Pathology Laboratory. PATIENTS AND METHODS: We selected 708 patients studied sequentially over 10 years with continuous Doppler and conventional angiography (gold standard). The data obtained independently with each technique were compared in order to establish the degree of concordance between them and the corresponding indicators of validity. Contingency tables were drawn up for different cut-off points corresponding to the different degrees of stenosis (50, 70 and 100%). The parameters for validity (sensitivity, specificity, predictive value and precision) were calculated in each case. RESULTS: The percentage coincidence of the two techniques was 91.95%. At the cut-off points there was a high degree of precision (> 94.35%). The specificity and negative predictive value of Doppler compared with angiography was over 95% and 96% respectively. CONCLUSIONS: The validity markers obtained in our laboratory support the technique using continuous Doppler as the ideal non-invasive diagnostic method for carotid stenosis and this means that its systematic use is to be recommended in patients with suspected extracranial carotid disease. Moreover, the low cost of the equipment used as compared with other more sophisticated techniques should lead to its more widespread use as a first-line diagnostic method in all Neurology departments.