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In order to assess the accuracy of objective quantification of carotid flow disturbance, 147 carotid arteries were examined with continuous wave (CW) Doppler technique. The systolic spectral broadening index (SBI), determined as (maximum-mean)/maximum frequency, was calculated from the power spectrum and together with the peak frequency related to the angiographic degree of stenosis. Receiver operating characteristics curves were calculated and the SBI predicted disease with a specificity of 94%. On the other hand, the ability of the SBI to discriminate minor disease was not satisfactory. Both the SBI and the peak frequency were accurate in discriminating between greater or less than 50% stenosis. The study concludes that using CW Doppler the SBI can reliably predict carotid artery stenoses. For exclusion of minor lesions an additional test should be performed, e.g., pulsed Doppler spectral analysis.

The periorbital flow direction and internal carotid artery (ICA) angiogram were compared to the ICA pressure gradient across the stenosis and the distal ICA pressure in 51 patients subjected to carotid endarterectomy. All 17 patients with inverted periorbital flow had stenoses exceeding 50%. The remaining 16 patients with the same degree of stenosis had antegrade flow, which was also observed in all patients with less than 50% stenosis. In 16 of 17 patients with inverted periorbital flow, the mean pressure gradient exceeded 10 mmHg, whereas 33 of 34 patients with antegrade flow had gradients of 12 mmHg or less. For diagnostic purpose, the periorbital Doppler test is inferior to direct Doppler examination or angiography. However, as an adjunct to direct techniques, patients can be classified into 3 groups: Patients with less than 50% stenosis, Patients with 50% stenosis or more and good collaterals and, Patients with 50% stenosis or more and insufficient collaterals.