Combined oculopneumoplethysmography and duplex scan. Use in the noninvasive cerebrovascular laboratory examination

To determine the relative merits of oculopneumoplethysmography (OPG) (Gee) and duplex scanning of the carotid arteries, a retrospective analysis was made of 93 patients in a 12-month period who underwent noninvasive carotid studies followed by carotid angiography. The results for the duplex scan were 91% sensitivity, 86% specificity, and 89% overall accuracy in evaluation of 184 arteries. The OPG results were 59% sensitivity, 90% specificity, and 74% accuracy when applied to individual arteries. The sensitivity of OPG increased to 77% when applied to disease in the patient rather than in individual arteries. Analysis of cases in which the duplex scan and OPG were in agreement and disagreement suggested an important role for the OPG test despite its inferior accuracy compared with the duplex scan alone. The predictive value of an abnormal duplex scan result was 98% when the OPG was also abnormal, whereas it was 81% when the OPG was normal. The predictive value of a normal duplex scan result was 93% when the OPG was also normal, whereas it was 60% in those cases where the OPG was abnormal. We believe that the duplex scan should be the basic noninvasive evaluation of cerebrovascular disease, although the OPG continues to provide important information.