The clinical use of objective quantification of flow disturbance in carotid artery disease: correlation between spectral broadening index and arteriography.

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.