Comparison of oculoplethysmography/carotid phonoangiography with duplex scan/spectral analysis in the detection of carotid artery stenosis.

The accuracy of the duplex scan with spectral analysis (DS/SA) in predicting the presence of arteriographic carotid stenosis was compared to that of oculoplethysmography/carotid phonoangiography (OPG/CPA) in 234 vessels from 117 patients who had had both non-invasive studies in addition to independently interpreted arteriograms. The DS/SA with 212/234 (91%) overall correct responses was superior to the OPG/CPA which properly classified 181/234 (77%) of the vessels (p less than .01). Of major clinical impact was the superiority of the DS/SA (p less than .001) in identifying the 72 vessels with 50-99% stenosis. The OPG/CPA had a discouraging 39/72 (54%) false-negative rate in this group whereas the DS/SA missed only 9/72 (12%) of these arteries. Of those 39 incorrect responses for the OPG/CPA, 26/39 (67%) were in patients with a 50% or greater stenosis on the contralateral side. This is a recognized area of weakness for that test. Based on the results of this study, we have abandoned the use of the OPG/CPA in the evaluation of patients with suspected carotid stenosis and rely solely on the duplex scan with spectral analysis.