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

Abstract
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 phonoangiograpy (OPG/CPA); 234 vessels from 117 patients were analyzed who 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 < 0.01). Of major clinical impact was the superiority of the DS/SA (P < 0.001) in identifying the 72 vessels with 50-99% stenosis. The OPG/CPA had a discouraging 39/72 (54%) false-negative rate in this group while 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. The use of the OPG/CPA in the evaluation of patients with suspected carotid stenosis was abandoned and the duplex scan with spectral analysis was used.