Non-invasive tests as an indicator of carotid stenosis.

Between 1979 and 1985, non-invasive testing was done on 896 carotid arteries prior to angiography. The non-invasive studies included B-scan ultrasound, Doppler, and oculoplethysmography. Estimates of per cent stenosis arrived at by the non-invasive reader was correlated with the degree of stenosis found at angiography. The Pearson correlation coefficient for agreement between the non-invasive studies and angiography was 0.86. The mean absolute difference was 11 per cent. In 50 per cent of cases the results of the two examinations were identical. In 73 per cent of instances the non-invasive result was within 10 per cent of that of angiography. These results indicate that non-invasive testing can be highly accurate in estimating carotid stenosis and can be sustained over time.